RV-3028-C7
Application Manual

Application
Manual
RV-3028-C7
Extreme Low Power
Real-Time Clock Modulewith I2C-Bus Interface

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TABLE OF CONTENTS
1. OVERVIEW ....................................................................................................................................................... 6
1.1. GENERAL DESCRIPTION ......................................................................................................................... 6
1.2. APPLICATIONS ......................................................................................................................................... 7
1.3. ORDERING INFORMATION ...................................................................................................................... 7
2. BLOCK DIAGRAM ............................................................................................................................................ 8
2.1. PINOUT ...................................................................................................................................................... 92.2. PIN DESCRIPTION .................................................................................................................................... 92.3. FUNCTIONAL DESCRIPTION ................................................................................................................. 10
2.4. DEVICE PROTECTION DIAGRAM ......................................................................................................... 10
3. REGISTER ORGANIZATION ......................................................................................................................... 11
3.1. REGISTER CONVENTIONS .................................................................................................................... 11
3.2. REGISTER OVERVIEW ........................................................................................................................... 123.3. CLOCK REGISTERS ............................................................................................................................... 14
3.4. CALENDAR REGISTERS ........................................................................................................................ 16
3.5. ALARM REGISTERS ............................................................................................................................... 18
3.6. PERIODIC COUNTDOWN TIMER CONTROL REGISTERS .................................................................. 20
3.7. STATUS AND CONTROL REGISTERS .................................................................................................. 22
3.8. EVENT CONTROL REGISTER ............................................................................................................... 26
3.9. TIME STAMP REGISTERS ...................................................................................................................... 27
3.10. UNIX TIME REGISTERS .......................................................................................................................... 30
3.11. RAM REGISTERS .................................................................................................................................... 31
3.12. PASSWORD REGISTERS ....................................................................................................................... 32
3.13. EEPROM MEMORY CONTROL REGISTERS ........................................................................................ 33
3.14. ID REGISTER ........................................................................................................................................... 35
3.15. CONFIGURATION EEPROM WITH RAM MIRROR REGISTERS .......................................................... 35
3.15.1. EEPROM RESERVED ...................................................................................................................... 35
3.15.2. EEPROM PASSWORD ENABLE REGISTER .................................................................................. 35
3.15.3. EEPROM PASSWORD REGISTERS ............................................................................................... 36
3.15.4. EEPROM CLKOUT REGISTER ........................................................................................................ 37
3.15.5. EEPROM OFFSET REGISTER ........................................................................................................ 38
3.15.6. EEPROM BACKUP REGISTER ....................................................................................................... 39
3.16. USER EEPROM ....................................................................................................................................... 40
3.17. RESERVED EEPROM ............................................................................................................................. 40
3.18. REGISTER RESET VALUES SUMMARY ............................................................................................... 41
4. DETAILED FUNCTIONAL DESCRIPTION .................................................................................................... 44
4.1. POWER ON RESET (POR)...................................................................................................................... 44
4.2. AUTOMATIC BACKUP SWITCHOVER FUNCTION............................................................................... 45
4.2.1. SWITCHOVER DISABLED ............................................................................................................... 46
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4.2.2. DIRECT SWITCHING MODE (DSM) ................................................................................................ 46
4.2.3. LEVEL SWITCHING MODE (LSM) ................................................................................................... 47
4.3. TRICKLE CHARGER ............................................................................................................................... 48
4.4. PROGRAMMABLE CLOCK OUTPUT .................................................................................................... 48
4.4.1. CLKOUT FREQUENCY SELECTION............................................................................................... 49
4.4.2. NORMAL CLOCK OUTPUT .............................................................................................................. 49
4.4.3. INTERRUPT CONTROLLED CLOCK OUTPUT ............................................................................... 49
4.4.4. SYNCHRONIZED ENABLE/DISABLE .............................................................................................. 50
4.4.5. CLOCK OUTPUT SCHEME .............................................................................................................. 51
4.5. SETTING AND READING THE TIME ...................................................................................................... 52
4.5.1. SETTING THE TIME ......................................................................................................................... 53
4.5.2. READING THE TIME ........................................................................................................................ 53
4.6. EEPROM READ/WRITE .......................................................................................................................... 54
4.6.1. POR REFRESH (ALL CONFIGURATION EEPROM  RAM) ......................................................... 54
4.6.2. AUTOMATIC REFRESH (ALL CONFIGURATION EEPROM  RAM) ........................................... 54
4.6.3. UPDATE (ALL CONFIGURATION RAM  EEPROM) .................................................................... 54
4.6.4. REFRESH (ALL CONFIGURATION EEPROM  RAM) .................................................................. 54
4.6.5. WRITE TO ONE EEPROM BYTE (EEDATA (RAM)  EEPROM) .................................................. 55
4.6.6. READ ONE EEPROM BYTE (EEPROM  EEDATA (RAM)) .......................................................... 55
4.6.7. EEBUSY BIT ..................................................................................................................................... 56
4.6.8. EEPROM READ/WRITE CONDITIONS ........................................................................................... 57
4.6.9. USE OF THE CONFIGURATION REGISTERS ............................................................................... 57
4.7. INTERRUPT OUTPUT ............................................................................................................................. 58
4.7.1. SERVICING INTERRUPTS .............................................................................................................. 58
4.7.2. INTERRUPT SCHEME ..................................................................................................................... 59
4.8. PERIODIC COUNTDOWN TIMER INTERRUPT FUNCTION ................................................................. 61
4.8.1. PERIODIC COUNTDOWN TIMER DIAGRAM.................................................................................. 62
4.8.2. USE OF THE PERIODIC COUNTDOWN TIMER INTERRUPT ....................................................... 63
4.8.3. FIRST PERIOD DURATION ............................................................................................................. 65
4.8.4. SINGLE MODE (TRPT = 0) .............................................................................................................. 65
4.8.5. REPEAT MODE (TRPT = 1) ............................................................................................................. 65
4.9. PERIODIC TIME UPDATE INTERRUPT FUNCTION ............................................................................. 66
4.9.1. PERIODIC TIME UPDATE DIAGRAM .............................................................................................. 66
4.9.2. USE OF THE PERIODIC TIME UPDATE INTERRUPT ................................................................... 67
4.10. ALARM INTERRUPT FUNCTION............................................................................................................ 68
4.10.1. ALARM DIAGRAM ............................................................................................................................ 68
4.10.2. USE OF THE ALARM INTERRUPT .................................................................................................. 69
4.11. EXTERNAL EVENT INTERRUPT FUNCTION ........................................................................................ 70
4.11.1. EXTERNAL EVENT DIAGRAM ........................................................................................................ 71
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4.11.2. USE OF THE EXTERNAL EVENT INTERRUPT .............................................................................. 72
4.11.3. EDGE DETECTION (ET = 00) .......................................................................................................... 73
4.11.4. LEVEL DETECTION WITH FILTERING (ET ≠ 00) ........................................................................... 73
4.12. AUTOMATIC BACKUP SWITCHOVER INTERRUPT FUNCTION ......................................................... 74
4.12.1. AUTOMATIC BACKUP SWITCHOVER DIAGRAM .......................................................................... 75
4.12.2. USE OF THE AUTOMATIC BACKUP SWITCHOVER INTERRUPT ............................................... 76
4.13. POWER ON RESET INTERRUPT FUNCTION ....................................................................................... 77
4.13.1. POWER ON RESET DIAGRAM ....................................................................................................... 77
4.13.2. USE OF THE POWER ON RESET INTERRUPT ............................................................................. 78
4.14. TIME STAMP FUNCTION ........................................................................................................................ 79
4.15. FREQUENCY OFFSET CORRECTION ................................................................................................... 81
4.15.1. EEOFFSET VALUE DETERMINATION............................................................................................ 81
4.15.2. VERIFICATION OF THE CORRECTED TIME ACCURACY ............................................................ 81
4.16. UNIX TIME COUNTER ............................................................................................................................. 82
4.16.1. SETTING THE UNIX TIME ............................................................................................................... 82
4.16.2. READING THE UNIX TIME .............................................................................................................. 84
4.17. RESET BIT FUNCTION ........................................................................................................................... 85
4.18. USER PROGRAMMABLE PASSWORD ................................................................................................. 87
4.18.1. ENABLE/DISABLE WRITE PROTECTION....................................................................................... 87
4.18.2. CHANGING PASSWORD ................................................................................................................. 88
4.18.3. FLOWCHART.................................................................................................................................... 89
2

5. I C INTERFACE .............................................................................................................................................. 90
5.1. BIT TRANSFER ....................................................................................................................................... 90
5.2. START AND STOP CONDITIONS .......................................................................................................... 90
5.3. DATA VALID ............................................................................................................................................ 91
5.4. SYSTEM CONFIGURATION.................................................................................................................... 91
5.5. ACKNOWLEDGE ..................................................................................................................................... 92
5.6. SLAVE ADDRESS ................................................................................................................................... 93
5.7. WRITE OPERATION ................................................................................................................................ 93
5.8. READ OPERATION AT SPECIFIC ADDRESS ....................................................................................... 94
5.9. READ OPERATION ................................................................................................................................. 94
5.10. I2C-BUS IN SWITCHOVER CONDITION ................................................................................................. 95
6. ELECTRICAL SPECIFICATIONS................................................................................................................... 96
6.1. ABSOLUTE MAXIMUM RATINGS .......................................................................................................... 96
6.2. OPERATING PARAMETERS .................................................................................................................. 97
6.2.1. TYPICAL CHARACTERISTICS ........................................................................................................ 99
6.3. OSCILLATOR PARAMETERS .............................................................................................................. 100
6.3.1. XTAL FREQUENCY VS. TEMPERATURE CHARACTERISTICS ................................................. 100
6.4. POWER ON AC ELECTRICAL CHARACTERISTICS .......................................................................... 101
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6.5. I2C-BUS CHARACTERISTICS ............................................................................................................... 102
7. TYPICAL APPLICATION CIRCUITS ............................................................................................................ 103
7.1. NO BACKUP SOURCE / EVENT INPUT NOT USED ........................................................................... 103
7.2. NON-RECHARGEABLE BACKUP SOURCE / EVENT INPUT USED (ACTIVE HIGH) ...................... 104
7.3. RECHARGEABLE BACKUP SOURCE / EVENT INPUT USED (ACTIVE LOW) ................................ 105
7.4. NO BACKUP SOURCE / EVENT INPUT USED (“WAKE-UP”& “POWER SWITCH”) ....................... 106
8. PACKAGE ..................................................................................................................................................... 107
8.1. DIMENSIONS AND SOLDER PAD LAYOUT ........................................................................................ 107
8.1.1. RECOMMENDED THERMAL RELIEF ........................................................................................... 107
8.2. MARKING AND PIN #1 INDEX .............................................................................................................. 108
9. MATERIAL COMPOSITION DECLARATION & ENVIRONMENTAL INFORMATION ............................... 109
9.1. HOMOGENOUS MATERIAL COMPOSITION DECLARATION ........................................................... 109
9.2. MATERIAL ANALYSIS & TEST RESULTS .......................................................................................... 110
9.3. RECYCLING MATERIAL INFORMATION ............................................................................................ 111
9.4. ENVIRONMENTAL PROPERTIES & ABSOLUTE MAXIMUM RATINGS ........................................... 112
10. SOLDERING INFORMATION ....................................................................................................................... 113
11. HANDLING PRECAUTIONS FOR MODULES WITH EMBEDDED CRYSTALS ........................................ 114
12. PACKING & SHIPPING INFORMATION ...................................................................................................... 115
13. COMPLIANCE INFORMATION .................................................................................................................... 116
14. DOCUMENT REVISION HISTORY............................................................................................................... 116

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RV-3028-C7
Extreme Low Power Real-Time Clock (RTC) Module with I2C-Bus Interface
1. OVERVIEW
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RTC module with built-in 32.768 kHz “Tuning Fork” crystal oscillator
Counters for seconds, minutes, hours, date, month, year and weekday
32-bit UNIX Time counter
Automatic leap year correction: 2000 to 2099
Aging compensation with user programmable EEPROM Offset value (Factory Calibrated value may bechanged by the user)
Periodic Countdown Timer Interrupt function; interrupt output also in VBACKUP Power state
Periodic Time Update Interrupt function (seconds, minutes); interrupt output also in VBACKUP Power state
Alarm Interrupts for weekday or date, hour and minute settings; interrupt output also in VBACKUP Power
state
External Event Input with Interrupt and Time Stamp function; interrupt output also in VBACKUP Powerstate
Factory calibrated time accuracy: ±1 ppm @ 25°C (EEPROM Offset value may be changed by the user)
32.768 kHz Xtal oscillator frequency accuracy: ±5 ppm @ 25°C
43 bytes of user EEPROM
Configuration registers stored in EEPROM and mirrored in RAM
User programmable password for write protection of the time, control and configuration registers
I2C-bus interface (up to 400 kHz)
Programmable Clock Output
o Enable/disable by CLKOE bit
o Enable by an Interrupt functiono 32.768 kHz, 8192 Hz, 1024 Hz, 64 Hz, 32 Hz, 1 Hz
o Periodic countdown timer interrupt as clock output frequency
o Synchronized enable/disable
Automatic Backup switchover with Interrupt and Time Stamp function
Internal Power On Reset (POR) with Interrupt function
Trickle charger
Wide Timekeeping voltage range: 1.1 to 5.5 V
Wide interface operating voltage: 1.2 to 5.5 V
Extreme low current consumption: 45 nA (VDD = 3.0 V, TA = 25°C)
Operating temperature range: -40 to +85°C
Ultra small and compact C7 package size (3.2 x 1.5 x 0.8 mm), RoHS-compliant and 100% lead-free
Automotive qualification according to AEC-Q200 available

1.1. GENERAL DESCRIPTION
The RV-3028-C7 is a CMOS real-time clock/calendar module with an automatic backup switchover circuit and is
optimized for extreme low power consumption. It provides full RTC function with programmable counters, alarm,
selectable interrupt and clock output functions and also a 32-bit UNIX Time counter. The internal EEPROM memory
hosts all configuration settings and allows for additional user memory. An EEOffset value allows compensating thefrequency deviation of the 32.768 kHz clock. Addresses and data are transmitted via an I2C-bus interface forcommunication with a host controller. The Address Pointer is incremented automatically after each written or readdata byte.
This ultra small RTC module has been specially designed for miniature and cost sensitive high volume applications.

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1.2. APPLICATIONSThe RV-3028-C7 RTC module combines key functions with outstanding performance in an ultra small ceramic
package: Extreme Low Power consumption
 Smallest RTC module (embedded XTAL) in an ultra-small 3.2 x 1.5 x 0.8 mm lead-free ceramic package
These unique features make this product perfectly suitable for many applications: Communication: IoT / Wearables / Wireless Sensors and Tags / Handsets
 Automotive:
M2M / Navigation & Tracking Systems / Dashboard / Tachometers / Engine Controller
Car Audio & Entertainment Systems
 Metering:
E-Meter / Heating Counter / Smart Meters / PV Converter/ Utility metering Outdoor:
ATM & POS systems / Surveillance & Safety systems / Ticketing Systems
 Medical:
Glucose Meter / Health Monitoring Systems
 Safety:
Security & Camera Systems / Door Lock & Access Control / Tamper Detection
 Consumer:
Gambling Machines / TV & Set Top Boxes / White Goods
 Automation:
PLC / Data Logger / Home & Factory Automation / Industrial and Consumer Electronics

1.3. ORDERING INFORMATION
Example:Code
TA (Standard)
Code
QC (Standard)
QA

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RV-3028-C7

TA

QC

Operating temperature range-40 to +85°C
Qualification
Commercial Grade
Automotive Grade AEC-Q200

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2. BLOCK DIAGRAMVBACKUP
VDD
VSS

SCL

SDA

6

POWER
CONTROL

7

5

3

4

I2C-BUSINTERFACEFREQUENCY
OFFSETCOMPENSATIONDIVIDERSYSTEMCONTROLLOGICXTAL
OSCILLATOR

CLKOUT

1

2
INT
EVI

8

INPUT
OUTPUT
CONTROL

RAM
Seconds
Minutes
Hours
Weekday
Date
Month
Year
Minutes Alarm
Hours Alarm
Weekday Alarm
Date Alarm
Timer Value 0
Timer Value 1
Timer Status 0
Timer Status 1
StatusControl 1
Control 2
GP Bits
CLKIM
Event Control
Count TS
Seconds TS
Minutes TS
Hours TS
Date TSMonth TSYear TS
UNIX Time 0
UNIX Time 1
UNIX Time 2
UNIX Time 3
User RAM 1

00

RAMUser RAM 2
PW 0
PW 1
PW 2
PW 3
EEADDR
EEDATA
EECMD
ID

20

28

Configuration EEPROM
with RAM mirror

0F
10

EEPWE
EEPW 0EEPW 1EEPW 2EEPW 3
EEPROM Clkout
EEPROM Offset
EEPROM Backup

30

37

User EEPROM

43 Bytes ofuser EEPROM(00h – 2Ah)

1F

RESET

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2.1. PINOUT
RV-3028-C7 Package: (top view)

#8

#5

3028
#1

#4

#1

CLKOUT

#2

INT

#3

SCL

#4

SDA

#5

VSS

#6

VBACKUP

#7

VDD

#8

EVI

2.2. PIN DESCRIPTION
Symbol

CLKOUT

Pin #1

Description
Clock Output; push-pull; Normal and Interrupt driven clock output can be activated concurrently:
1. Normal clock output can be controlled by the CLKOE bit (EEPROM 35h) when CLKF = 0.
When CLKOE is set to 1 (default), the CLKOUT pin drives the square wave on the
CLKOUT pin. When CLKOE bit is set to 0, the CLKOUT pin is LOW.
2. Interrupt driven clock output can be controlled by interrupt events when CLKOE = 0.
When CLKIE bit (10h) is set to 1 the occurrence of the interrupt selected in the Clock
Interrupt Mask Register (12h) allows the square wave output on the CLKOUT pin. Writing
0 to CLKIE will disable new interrupts from driving square wave on CLKOUT. When
CLKF flag is cleared, the CLKOUT pin is LOW.
Depending of the settings in the FD field (EEPROM 35h), the CLKOUT pin can drive the squarewave of 32.768 kHz (default), 8192 Hz, 1024 Hz, 64 Hz, 32 Hz or 1 Hz, or the predefined periodic
countdown timer interrupt. When FD field is 111 the CLKOUT pin is LOW.
When CLKSY bit (EEPROM 35h) set to 1, the enabling and disabling of the clock output issynchronized. CLKSY has no effect on the timer interrupt signal.

̅̅̅̅̅
INT

2

SCL

3

SDA

4

VSS

5

VBACKUP

6

VDD

7

EVI

8

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In VBACKUP Power state, the CLKOUT pin is LOW.
Interrupt Output; open-drain; active LOW; requires pull-up resistor when used; used to output
Periodic Countdown Timer, Periodic Time Update, Alarm, External Event, Automatic Backup
Switchover and Power On Reset Interrupt signals. Interrupt output also in VBACKUP Power state.
I2C Serial Clock Input; requires pull-up resistor. In VBACKUP Power state, the SCL pin is disabled.
I2C Serial Data Input-Output; open-drain; requires pull-up resistor. In VBACKUP Power state, theSDA pin is disabled (high impedance).
Ground.
Backup Supply Voltage. When the backup switchover function is not needed, VBACKUP must be tied
to VSS with a 10 kΩ resistor.
Power Supply Voltage.
External Event Input; used for interrupt generation, interrupt driven clock output and time stampfunction. Remains active also in VBACKUP Power state. This pin should not be left floating.

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2.3. FUNCTIONAL DESCRIPTION
The RV-3028-C7 is an extreme-low power CMOS based Real-Time-Clock Module with embedded 32.768 kHz crystal
oscillator. It includes an Automatic Backup switchover function with a Trickle charger where the interrupt output pin
INT is also working in VBACKUP Power state. The clock output on CLKOUT pin can be enabled normally via
command over I2C interface or can be interrupt driven and synchronized clock output enable/disable on CLKOUT pin
can be freely selected. The configuration registers are stored permanently in EEPROM and mirrored in RAM in orderthat the RTC module is still configured correctly even after power down. For safety against inadvertent overwriting
the time, control and configuration registers can be protected by a User Programmable Password. Additionally, there
is an EEPROM Offset value customer use for aging correction.
The RV-3028-C7 provides standard Clock & Calendar function including seconds, minutes, hours (12 or 24 h),
weekdays, date, months, years (with leap year correction) and interrupt functions for the Periodic Countdown Timer,
Periodic Time Update, Alarm, External Event, Automatic Backup Switchover and Power On Reset. All is accessible
via I2C-bus (2-wire Interface). The interrupt functions and the Time Stamp of the External Event function are also
working in VBACKUP Power state. Beside the standard RTC functions a 32-bit UNIX Time counter and 43 Bytes ofUser Memory EEPROM and 2 Bytes of User RAM are provided. A further Byte can be used as User RAM when the
Periodic Countdown Timer is not used (Timer Value register 0Ah) and a further Byte when the Alarm function is not
used (Alarm register 07h).
The registers are accessed by selecting a register address and then performing read or write operations. Multiple
reads or writes can be performed in a single access, with the address automatically incremented after each byte by
the Address Pointer. When address is automatically incremented, wrap around occurs from address 3Fh to address
00h (see figure below). All registers are designed as addressable 8-bit registers despite the fact that not all registers
and bits are implemented.
Handling address registers:
Address
00h
wrap around

01h
autoincrement

02h
03h
:
3Dh
3Eh
3Fh

2.4. DEVICE PROTECTION DIAGRAM

CLKOUT
INT
SCL
SDA

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8

2

7

3

6

4

5

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VDD
VBACKUP
VSS

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3. REGISTER ORGANIZATION

RAM Registers at addresses 00h to 28h are accessed by selecting a register address and then performing
read or write operations. Multiple reads or writes may be executed in a single access, with the address
automatically incrementing after each byte.
The Configuration Registers at addresses 30h to 37h are memorized in EEPROM and mirrored in RAM. For
the RAM mirror, multiple reads or writes may be executed in a single access, with the address automaticallyincrementing after each byte.
There are 43 bytes of non-volatile user memory EEPROM at addresses 00h to 2Ah for general use.

The following tables summarize the function of each register.

3.1. REGISTER CONVENTIONS
The conventions in this table serve as a key for the register overview and individual register diagrams:
Convention(Conv.)
R
W
R/WP
WP
*WP
Prot.

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Description
Read only. Writing to this register has no effect.
Write only. Returns 0 when read.
Read: Always readable. Write: Can be write-protected by password.
Write only. Returns 0 when read. Can be write-protected by password.
EEPW registers: RAM mirror is Write only. Returns 0 when read. EEPROM can be READ when Unlocked.
Protected. Writing to this register has no effect.

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3.2. REGISTER OVERVIEW
After reset, all registers are set according to Table in section REGISTER RESET VALUES SUMMARY.
Register Definitions; RAM, Address 00h to 3Fh:
Address00h01hFunction

Conv.

Seconds
R/WP
Minutes
R/WP
Hours (24 hour)
02h
R/WP
Hours (12 hour)03h
Weekday
R/WP
04h
Date
R/WP
05h
Month
R/WP
06h
Year
R/WP
07h
Minutes Alarm
R/WP
Hours Alarm (24h)08h
R/WP
Hours Alarm (12h)Weekday Alarm
09h
R/WP
Date Alarm
0Ah
Timer Value 0
R/WP
0Bh
Timer Value 1
R/WP
0Ch
Timer Status 0R
Timer Status 1
0Dh
R
shadow
0Eh
Status
R/WP
0Fh
Control 1
R/WP
10h
Control 2
R/WP
11h
GP Bits
R/WP
12h
Clock Int. Mask
R/WP
13h
Event Control
R/WP
14h
Count TSR
15h
Seconds TSR
16h
Minutes TS
R
Hours TS (24h)17h
R
Hours TS (12h)18hDate TSR
19h
Month TS
R
1Ah
Year TS
R
1Bh
UNIX Time 0
R/WP
1Ch
UNIX Time 1
R/WP
1Dh
UNIX Time 2
R/WP
1EhUNIX Time 3
R/WP
1FhUser RAM 1
R/WP
20h
User RAM 2
R/WP
21h
Password 0W
22h
Password 1W
23h
Password 2W
24h
Password 3W25h
EE Address
R/WP
26h
EE Data
R/WP
27h
EE Command
WP
28h
ID
R
29h and 2Ah
RESERVEDProt.
2Ch to 2Fh
RESERVEDProt.
38h to 3Fh
RESERVEDProt.
○ Read only. Always 0.
- Bit not implemented. Will return a 0 when read.

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Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

○
○

40
40

○

○

○
○
○
80
AE_M

○
○
○
40
40

AE_H

○

AE_WD

○

128
○
128

64
○
64

20
20
20
AMPM
○
20
○
20
20
20
AMPM
○
20
32
○
32

10
10
10
10
○
10
10
10
10
10
10
○
10
16
○
16

8
8
8
8
○
8
8
8
8
8
8
○
8
8
2048
8

4
4
4
4
4
4
4
4
4
4
4
4
4
4
1024
4

2
2
2
2
2
2
2
2
2
2
2
2
2
2
512
2

1
1
1
1
1
1
1
1
1
1
1
1
1
1
256
1

○

○

○

○

2048

1024

512

256

EEbusy
TRPT
TSE
○
128
○
○

CLKF
CLKIE
GP6
EHL
64
40
40

BSF
WADA
UIE
GP5
-

UF
USEL
TIE
GP4
-

○

○
○
80

○
○
40

AF
TE
EIE
GP2
CAIE
TSR
4
4
4
4
4
4
4
4

EVF

○

TF
EERD
AIE
GP3
CEIE
ET
○
32
16
8
20
10
8
20
10
8
20
10
8
AMPM
10
8
20
10
8
○
10
8
20
10
8
UNIX 0 [7:0]UNIX 1 [15:8]
UNIX 2 [23:16]
UNIX 3 [31:24]
RAM 1 data
RAM 2 data
PW 0 [7:0]
PW 1 [15:8]
PW 2 [23:16]
PW 3 [31:24]
EEADDR
EEDATA
EECMD
HID

PORF
TD

12_24
GP1
CTIE
TSOW
2
2
2
2
2
2
2
2

RESET
GP0
CUIE
TSS
1
1
1
1
1
1
1
1

VID
RESERVEDRESERVEDRESERVED

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Extreme Low Power Real-Time Clock Module

RV-3028-C7

Register Definitions; Configuration EEPROM with RAM mirror, Address 2Bh and 30h to 37h:
Address

Function

Conv.

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

EEPROM
2Bh
R/WP
RESERVED (Must not be overwritten)
Reserved
EEPROM PW
30h
R/WP
EEPWE
EnableEEPROM
31h*WP
EEPW 0 [7:0]
Password 0
EEPROM
32h*WP
EEPW 1 [15:8]
Password 1
EEPROM
33h*WP
EEPW 2 [23:16]
Password 2
EEPROM
34h*WP
EEPW 3 [31:24]
Password 3
EEPROM
35h
R/WP CLKOE
CLKSY
PORIE
ClkoutEEPROM
36h
R/WP
EEOffset [8:1]
OffsetEEPROM
EEOffset
37h
R/WP
BSIE
TCE
FEDE
BSM
Backup[0]- Bit not implemented. Will return a 0 when read.
* EEPW registers: RAM mirror is Write only. Returns 0 when read. EEPROM can be READ when Unlocked.

Bit 1

Bit 0

FD

TCR

Register Definitions; User EEPROM, Address 00h to 2Ah:
Address

FunctionConv.

00h to 2AhUser EEPROM(43 Bytes)

R/WP

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

Bit 1

Bit 0

43 Bytes of non-volatile User EEPROM

Register Definitions; Reserved EEPROM, Address 2Ch to 2Fh and 38h to 3Fh:
Address
2Ch to 2Fh
38h to 3Fh

November 2021

Function
Reserved
EEPROM
Reserved
EEPROM

Conv.

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Prot.

RESERVEDProt.

RESERVED

13/116

Bit 2

Rev. 1.4

Micro Crystal
Extreme Low Power Real-Time Clock Module

RV-3028-C7

3.3. CLOCK REGISTERS
00h – Seconds
This register holds the count of seconds, in two binary coded decimal (BCD) digits. Values will be from 00 to 59.
Read: Always readable. Write: Can be write-protected by password.
Address

Function

Conv.

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

00h

Seconds
Reset

R/WP

○
0

40
0

20
0

10
0

8
0

4
0

2
0

1
0

Bit

Symbol7○

6:0

Seconds

Value

Description

0

Read only. Always 0.
Holds the count of seconds, coded in BCD format.
When writing to the Seconds register an eventual present memorized 1 Hz
update is reset and the prescaler frequencies from 8192 Hz to 1 Hz will bereset (same effect as RESET BIT FUNCTION).
When writing 1 to the RESET bit (10h) the Seconds register value remains
unchanged.

00 to 59

01h – Minutes
This register holds the count of minutes, in two binary coded decimal (BCD) digits. Values will be from 00 to 59.
Read: Always readable. Write: Can be write-protected by password.
Address

Function

Conv.

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

01h

Minutes
Reset

R/WP

○
0

40
0

20
0

10
0

8
0

4
0

2
0

1
0

Bit

Symbol

Value

7
6:0

○
Minutes000 to 59

November 2021

Description
Read only. Always 0.
Holds the count of minutes, coded in BCD format.

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Extreme Low Power Real-Time Clock Module

RV-3028-C7

02h – Hours
This register holds the count of hours, in two binary coded decimal (BCD) digits. If the 12_24 bit is cleared (default)(see STATUS AND CONTROL REGISTERS, 10h – Control 2) the values will be from 0 to 23. If the 12_24 bit is set,
the hour values will range from 1 to 12 and the AMPM bit will be 0 for AM hours and 1 for PM hours.
The value in the Hours register changes automatically between 12 and 24 hour mode when 12_24 bit is changed.
The value in the Hours Alarm register (08h) however must be rewritten.
Read: Always readable. Write: Can be write-protected by password.
Address

Function
Hours (24 hourmode)
– default value
Hours (12 hour
mode)
Reset

02h

Conv.

Bit 7

Bit 6

R/WP

○

○

0

0

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

20

10

8

4

2

1

AMPM

10

8

4

2

1

0

0

0

0

0

0

Hours (24 hour mode), 12_24 = 0 – default value
Bit

Symbol

7:6○
Hours (24 hour mode)– default value

5:0

Value
0
0 to 23

Description
Read only. Always 0.
Holds the count of hours, coded in BCD format.

Hours (12 hour mode), 12_24 = 1
Bit

Symbol

Value

7:6

○

5

AMPM

4:0

Hours (12 hour mode)00
1
1 to 12

Description
Read only. Always 0.
AM hours.
PM hours.
Holds the count of hours, coded in BCD format.

Hours values:
24 hour mode

12 hour mode

24 hour mode

12 hour mode

00
01
02
:
10
11

12 (AM 12)
01 (AM 1)
02 (AM 2):
10 (AM 10)
11 (AM 11)

12
13
14
:
22
23

32 (PM 12)
21 (PM 1)
22 (PM 2):
30 (PM 10)
31 (PM 11)

November 2021

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Extreme Low Power Real-Time Clock Module

RV-3028-C7

3.4. CALENDAR REGISTERS
03h – Weekday
This register holds the current day of the week. Each value represents one weekday that is assigned by the user.
Values will range from 0 to 6. The weekday counter is simply a 3-bit counter which counts up to 6 and then resets to0.
Read: Always readable. Write: Can be write-protected by password.
Address

Function

Conv.

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

03h

Weekday
Reset

R/WP

○
0

○
0

○
0

○
0

○
0

4
0

2
0

1
0

Bit

Symbol

Value

7:3
2:0

○
Weekday0
0 to 6

Bit 3

Bit 2

Bit 1

Bit 0

0

0
0
0
0
1
1
1

0
0
1
1
0
0
1

0
1
0
1
0
1
0

Weekday

Bit 7

Weekday 1 – Default value
Weekday 2
Weekday 3
Weekday 4
Weekday 5
Weekday 6
Weekday 7

0

Description
Read only. Always 0.
Holds the weekday counter value.
Bit 6

0

Bit 5

0

Bit 4

0

04h – Date
This register holds the current day of the month, in two binary coded decimal (BCD) digits. Values will range from 01
to 31. Leap years are correctly handled from 2000 to 2099.
Read: Always readable. Write: Can be write-protected by password.
Address

Function

Conv.

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

04h

Date
Reset

R/WP

○
0

○
0

20
0

10
0

8
0

4
0

2
0

1
1

Bit

Symbol

7:6

○

5:0

Date

November 2021

Value
001 to 31

Description
Read only. Always 0.
Holds the current date of the month, coded in BCD format.
– Default value = 01

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Extreme Low Power Real-Time Clock Module

RV-3028-C7

05h – Month
This register holds the current month, in two binary coded decimal (BCD) digits. Values will range from 01 to 12.
Read: Always readable. Write: Can be write-protected by password.
Address

Function

Conv.

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

05h

Month
Reset

R/WP

○
0

○
0

○
0

10
0

8
0

4
0

2
0

1
1

Bit

Symbol

Value

7:5
4:0

○
Month

0
01 to 12

Read only. Always 0.
Holds the current month, coded in BCD format.

Bit 7

Bit 6

MonthsJanuary – Default value
February
March
April
May
June
July
AugustSeptember
OctoberNovember
December

0

Description

0

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

0

0
0
0
0
0
0
0
0
0
1
1
1

0
0
0
0
0
0
0
1
1
0
0
0

0
0
0
1
1
1
1
0
0
0
0
0

0
1
1
0
0
1
1
0
0
0
0
1

1
0
1
0
1
0
1
0
1
0
1
0

06h – Year
This register holds the current year, in two binary coded decimal (BCD) digits. Values will range from 00 to 99. Leap
years are correctly handled from 2000 to 2099.
Read: Always readable. Write: Can be write-protected by password.
Address

Function

Conv.

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

06h

Year
Reset

R/WP

80
0

40
0

20
0

10
0

8
0

4
0

2
0

1
0

Bit

Symbol

Value

7:0

Year

00 to 99

November 2021

Description
Holds the current year, coded in BCD format. – Default value = 00

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Extreme Low Power Real-Time Clock Module

RV-3028-C7

3.5. ALARM REGISTERS
07h – Minutes Alarm
This register holds the Minutes Alarm Enable bit AE_M and the alarm value for minutes, in two binary coded decimal(BCD) digits. Values will range from 00 to 59.
Read: Always readable. Write: Can be write-protected by password.
Address

Function

Conv.

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

07h

Minutes Alarm
Reset

R/WP

AE_M
1

40
0

20
0

10
0

8
0

4
0

2
0

1
0

Bit

Symbol

7

AE_M

6:0

Minutes Alarm

Value
Description
Minutes Alarm Enable bit. Enables alarm together with AE_H and AE_WD(see USE OF THE ALARM INTERRUPT).
0
Minutes Alarm is enabled.
1
Minutes Alarm is disabled. – Default value
00 to 59 Holds the alarm value for minutes, coded in BCD format.

08h – Hours Alarm
This register holds the Hours Alarm Enable bit AE_H and the alarm value for hours, in two binary coded decimal(BCD) digits. If the 12_24 bit is cleared (default value) (see STATUS AND CONTROL REGISTERS, 10h – Control
2) the values will range from 0 to 23. If the 12_24 bit is set, the hour values will be from 1 to 12 and the AMPM bit willbe 0 for AM hours and 1 for PM hours.
If the 12_24 hour mode bit is changed then the value in the Hours Alarm register must be re-initialized.
Read: Always readable. Write: Can be write-protected by password.
Address08h

Function
Hours Alarm (24hour mode)– default value
Hours Alarm (12hour mode)
Reset

Conv.

Bit 7

Bit 6

R/WP

AE_H

○

1

0

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

20

10

8

4

2

1

AMPM

10

8

4

2

1

0

0

0

0

0

0

Hours Alarm (24 hour mode), 12_24 = 0 – default value
Bit

Symbol

7

AE_H

6

○
Hours Alarm (24 hourmode) – default value

5:0

Value
0
1
0
0 to 23

Description
Hours Alarm Enable bit (see USE OF THE ALARM INTERRUPT).
EnabledDisabled – Default value
Read only. Always 0.
Holds the alarm value for hours, coded in BCD format.

Hours Alarm (12 hour mode), 12_24 = 1
Bit

Symbol

7

AE_H

6

○

5

AMPM

4:0

Hours Alarm (12 hour
mode)

November 2021

Value
0
1
0
0
1
1 to 12

Description
Hours Alarm Enable bit (see USE OF THE ALARM INTERRUPT).
EnabledDisabled – Default value
Read only. Always 0.
AM hours.
PM hours.
Holds the alarm value for hours, coded in BCD format.

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Extreme Low Power Real-Time Clock Module

RV-3028-C7

09h – Weekday/Date Alarm
This register holds the Weekday/Date Alarm Enable bit AE_WD. If the WADA bit is 0 (Bit 5 in Register 0Fh), it holds
the alarm value for the weekday (weekdays assigned by the user), in two binary coded decimal (BCD) digits. Values
will range from 0 to 6. If the WADA bit is 1, it holds the alarm value for the date, in two binary coded decimal (BCD)
digits. Values will range from 01 to 31. Leap years are correctly handled from 2000 to 2099.
Read: Always readable. Write: Can be write-protected by password.
Address09h

Function

Conv.

Bit 7

Bit 6

R/WP

AE_WD

○

1

0

Weekday Alarm –default value
Date Alarm
Reset

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

○

○

○

4

2

1

20
0

10
0

8
0

4
0

2
0

1
0

Weekday Alarm, WADA = 0 – default value
Bit

Symbol

7

AE_WD

6:3
2:0

○
Weekday Alarm

Value
Description
Weekday/Date Alarm Enable bit. Enables alarm together with AE_M and AE_H
(see USE OF THE ALARM INTERRUPT).
0
Enabled
1
Disabled – Default value
0
Read only. Always 0.
0 to 6
Holds the weekday alarm value, coded in BCD format.

Date Alarm, WADA = 1
Bit

Symbol

7

AE_WD

6

○

5:0

Date Alarm

November 2021

Value
Description
Weekday/Date Alarm Enable bit. Enables alarm together with AE_M and AE_H
(see USE OF THE ALARM INTERRUPT).
0
Enabled
1
Disabled – Default value
0
Read only. Always 0.
Holds the alarm value for the date, coded in BCD format. The Reset value
01 to 3100 after POR has to be replaced by a valid value (01 to 31).

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Extreme Low Power Real-Time Clock Module

RV-3028-C7

3.6. PERIODIC COUNTDOWN TIMER CONTROL REGISTERS
0Ah – Timer Value 0This register is used to set the lower 8 bits of the 12 bit Timer Value (preset value) for the Periodic Countdown Timer.
This value will be automatically reloaded into the Countdown Timer when it reaches zero if the TRPT bit is 1. This
allows for periodic timer interrupts (see calculation below).
Read: Always readable. Write: Can be write-protected by password.
Address

Function

Conv.

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

0Ah

Timer Value 0
Reset

R/WP

128
0

64
0

32
0

16
0

8
0

4
0

2
0

1
0

Bit

SymbolValue

7:0

Timer Value 000h toFFh

Description
The Timer Value for the Periodic Countdown Timer in binary format (lower
8 bit) (see USE OF THE PERIODIC COUNTDOWN TIMER). When read,
only the preset value is returned and not the actual value.
When the Periodic Countdown Timer Interrupt function is not used, register
0Ah can be used as RAM byte.

0Bh – Timer Value 1
This register is used to set the upper 4 bits of the 12 bit Timer Value (preset value) for the Periodic Countdown Timer.
This value will be automatically reloaded into the Countdown Timer when it reaches zero if the TRPT bit is 1. This
allows for periodic timer interrupts (see calculation below).
Read: Always readable. Write: Can be write-protected by password.
Address

Function

Conv.

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

0Bh

Timer Value 1
Reset

R/WP

○
0

○
0

○
0

○
0

2048
0

1024
0

512
0

256
0

Bit

Symbol

7:4

○

3:0

Timer Value 1

Value00h to Fh

Description
Read only. Always 0.
The Timer Value for the Periodic Countdown Timer in binary format (upper
4 bit) (see USE OF THE PERIODIC COUNTDOWN TIMER). When read,
only the preset value is returned and not the actual value.

Countdown Period in seconds:
Countdown Period =November 2021

Timer Value
Timer Clock Frequency

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Extreme Low Power Real-Time Clock Module

RV-3028-C7

0Ch – Timer Status 0This register holds the lower 8 bits of the current 12 bit value of the Periodic Countdown Timer.
Read only. Writing to this register has no effect.
Address

Function

0Ch

Timer Status 0
Reset

Bit

Symbol7:0Timer Status 0

Conv.

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

R

128
0

64
0

32
0

16
0

8
0

4
0

2
0

1
0

Value
00h toFFh

Description
The current value of the Periodic Countdown Timer in binary format (lower
8 bit) (see USE OF THE PERIODIC COUNTDOWN TIMER).

0Dh – Timer Status 1 shadow
This register holds the upper 4 bits of the current 12 bit value of the Periodic Countdown Timer.
Read only. Writing to this register has no effect.
Address

Function

0Dh

Timer Status 1
Reset

Conv.

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

R

○
0

○
0

○
0

○
0

2048
0

1024
0

512
0

256
0

Bit

SymbolValue

Description

7:4

○

3:0

Timer Status 1

0
0h to
Fh

Read only. Always 0.
The current value of the Periodic Countdown Timer in binary format (upper
4 bit) (see USE OF THE PERIODIC COUNTDOWN TIMER).

When TE bit (0Fh) is set to 1, the Timer Status 0 and Timer Status 1 shadow registers hold the current countdown
value. When a 0 is written to the TE bit, the Timer Status 0 and Timer Status 1 registers store the last updated value.
Reading the Timer Status 0 value updates the Timer Status 1 shadow register. Reading only the Timer Status 1
shadow register will return the not-updated Timer Status 1 shadow register value, memorized while reading Timer
Status 0.

November 2021

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Extreme Low Power Real-Time Clock Module

RV-3028-C7

3.7. STATUS AND CONTROL REGISTERS
0Eh – Status
This register is used to detect the occurrence of various interrupt events and reliability problems in internal data.
Read: Always readable. Write: Can be write-protected by password.
Address

Function

Conv.

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

0Eh

StatusReset

R/WP

EEbusy
10

CLKF
0

BSF
0

UF
01

TF
0

AF
0

EVF
0

PORF
1

Bit

Symbol7

EEbusy

6

CLKF

5

BSF

4

UF

3

TF

2

AF

Value

Description
EEPROM Memory Busy Status Bit – (Read Only)(see EEPROM READ/WRITE)0
The transfer is finished.
Indicates that the EEPROM is currently handling a read or write request
and will ignore any further commands until the current one is finished.
1
At power up (POR) a refresh is automatically generated. The time of thisfirst refreshment is tPREFR = ~66 ms. After the refreshment is finished;
EEbusy is cleared to 0 automatically.
Clock Output Interrupt Flag (see PROGRAMMABLE CLOCK OUTPUT)
No event detected. When cleared to 0 the frequency output will stop0
depending on CLKSY and CLKOUT settings.
If set to 0 beforehand, indicates the occurrence of an interrupt driven clock1
output on CLKOUT pin. The value 1 is retained until a 0 is written by theuser.
Backup Switch Flag (see AUTOMATIC BACKUP SWITCHOVER FUNCTION)
No backup switchover detected. At power up (POR) this flag is0
automatically cleared to 0. When the backup switchover function isdisabled (BSM field = 00 or 10) BSF is always logic 0.
If set to 0 beforehand, indicates that a switchover from main power VDD to
VBACKUP has occurred. The value 1 can be cleared by writing a 0 to the bit if
1
RTC module is in VDD Power state.
Caution: The EVF flag is also set by an event of the Backup Switchover
function when bits TSS (13h) and TSE (10h) are set to 1.
Periodic Time Update Flag(see PERIODIC TIME UPDATE INTERRUPT FUNCTION)0
No event detected.
If set to 0 beforehand, indicates the occurrence of a Periodic Time Update
Interrupt event. The value 1 is retained until a 0 is written by the user.
1
After power up (POR) the Second update is selected and the UF flag is set
to 1 within one second.
Periodic Countdown Timer Flag(see PERIODIC COUNTDOWN TIMER INTERRUPT FUNCTION)
No event detected.
̅̅̅̅̅ and CLKOUT pins are LOW because of a Countdown Timer0
When the INT
event, their tRTN1 – signals are cancelled as soon as TF flag is cleared to 0.
If set to 0 beforehand, indicates the occurrence of a Periodic Countdown
1Timer Interrupt event. The value 1 is retained until a 0 is written by theuser.
Alarm Flag (see ALARM INTERRUPT FUNCTION)0
No event detected.
If set to 0 beforehand, indicates the occurrence of an Alarm Interrupt
1
event. The value 1 is retained until a 0 is written by the user.
Event Flag (see EXTERNAL EVENT INTERRUPT FUNCTION)
0

1

EVF
1

0
0

PORF
1

November 2021

No event detected.
If set to 0 beforehand, indicates the occurrence of an External Event or a
Backup Switchover. The value 1 is retained until a 0 is written by the user.
The EVF flag is set to 1 when:
External event occurs and TSS = 0 and (EIE = 1 or TSE = 1).
Backup switchover occurs and TSS = 1 and (EIE = 1 or TSE = 1).
Power On Reset Flag
No voltage drop detected.
If set to 0 beforehand, indicates a voltage drop below VPOR. The data in thedevice are no longer valid and all registers must be initialized. The value 1
is retained until a 0 is written by the user. At power up (POR) the value isset to 1, the user has to write 0 to the flag to use it.

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Extreme Low Power Real-Time Clock Module

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0Fh – Control 1
This register is used to specify the target for the Alarm Interrupt function and the Periodic Time Update Interrupt
function and to select or set operations for the Periodic Countdown Timer.
Read: Always readable. Write: Can be write-protected by password.
Address

Function

Conv.

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

0Fh

Control 1
Reset

R/WP

TRPT
0

0

WADA
0

USEL
0

EERD
0

TE
0

Bit

Symbol

7

TRPT

6

-

5

WADA

4

USEL

3

EERD

2

TE

1:0

TD

TD value
00
01
10
11

November 2021

Timer Clock Frequency
4096 Hz – Default value
64 Hz
1 Hz
1/60 Hz

Bit 1

Bit 0
TD

0

0

Value
Description
Timer Repeat bit. Specifies either Single or Repeat Mode for the Periodic Countdown
Timer Interruption function(see PERIODIC COUNTDOWN TIMER INTERRUPT FUNCTION).
Single Mode is selected. When the Countdown Timer is enabled (TE = 1) it
0will halt when it reaches zero and TE is automatically cleared.
– Default value
Repeat Mode is selected. When the Countdown Timer is enabled (TE = 1)
1
it automatically reloads the value from the Timer Value registers uponreaching 0, and continues counting.
0
Bit not implemented. Will return a 0 when read.
Weekday Alarm / Date Alarm selection bit. This bit is used to specify either the
Weekday or Date as the source for the Alarm Interrupt function(see ALARM INTERRUPT FUNCTION).
0
Weekday is the source for the Alarm Interrupt function. – Default value
1
Date is the source for the Alarm Interrupt function.
Update Interrupt Select bit. Specifies either Second or Minute update for the Periodic
Time Update Interrupt function (see PERIODIC TIME UPDATE INTERRUPTFUNCTION).
Writing 1 to the RESET bit or writing to the Seconds register affects the length of thecurrent update period (see RESET BIT FUNCTION).
0
Second update (Auto reset time tRTN2 = 500 ms). – Default value
1
Minute update (Auto reset time tRTN2 = 7.813 ms).
EEPROM Memory Refresh Disable bit. When 1, disables the automatic refresh of theConfiguration Registers from the EEPROM Memory(see AUTOMATIC REFRESH (ALL CONFIGURATION EEPROM  RAM)).
Refresh is active. All data in the Configuration Registers are refreshed by
the data stored in the EEPROM each 24 hours, at date increment (at the0
beginning of the last second before midnight). The time of this automaticrefreshment is tAREFR = ~3.5 ms. Refresh is only active when RTC is not in
VBACKUP mode. – Default value
1
Refresh is disabled.
Periodic Countdown Timer Enable bit. This bit controls the start/stop setting for the
Periodic Countdown Timer Interruption function(see PERIODIC COUNTDOWN TIMER INTERRUPT FUNCTION).
Stops the Periodic Countdown Timer Interrupt function. TE is also0
automatically cleared when Single Mode is selected (TRPT = 0) and when
the Countdown Timer reaches zero. – Default value
Starts the Periodic Countdown Timer Interrupt function (a countdown starts
1from the preset value set in Timer Value registers).
Timer Clock Frequency selection. Sets the countdown source clock for the
Periodic Countdown Timer Interrupt function. With this setting the Auto
reset time tRTN1 is also defined.
When the clock source has been set to Second update (1 Hz) or Minute
00 to 11 update (1/60 Hz), the timing of both, countdown and interrupts, iscoordinated with the clock update timing. See table below (see also
PERIODIC COUNTDOWN TIMER INTERRUPT FUNCTION).
Writing 1 to the RESET bit or writing to the Seconds register affects thelength of the current countdown period (see RESET BIT FUNCTION).

Countdown period
244.14 μs
15.625 ms
1s
60 s

tRTN1

Effect when writing 1 to
the RESET bit or whenwriting to the Seconds
register

122 μs
7.813 ms

23/116Affects current period

Rev. 1.4

Micro Crystal
Extreme Low Power Real-Time Clock Module

RV-3028-C7

10h – Control 2This register is used to control the interrupt event output for the ̅̅̅̅̅
INT pin, the stop/start status of clock and calendar
operations, the interrupt controlled clock output on CLKOUT pin, the hour mode and the time stamp enable.
Read: Always readable. Write: Can be write-protected by password.
Address

Function

Conv.

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

10h

Control 2
Reset

R/WP

TSE
0

CLKIE
0

UIE
0

TIE
0

AIE
0

EIE
0

12_24
0

RESET
0

Bit

Symbol

7

TSE

6

CLKIE

5

UIE

4

TIE

3

AIE

2

EIE

1

12_24

0

RESET

November 2021

Value

Description

Time Stamp Enable bit (see TIME STAMP FUNCTION)
0
Disables the time stamp function. – Default value
1
Enables the Time stamp function.
Interrupt Controlled Clock Output Enable bit.
When enabled, it is possible to wake-up an external system by outputting a frequency.
(see PROGRAMMABLE CLOCK OUTPUT)
0
Disabled – Default value
When set to 1, the clock output on CLKOUT pin is automatically enabled
when an interrupt occurs, based on the Clock Interrupt Mask Register1(12h) and according to clock setting defined by the FD field.
This function is disabled in VBACKUP Power state.
Periodic Time Update Interrupt Enable bit(see PERIODIC TIME UPDATE INTERRUPT FUNCTION)
No interrupt signal is generated on ̅̅̅̅̅
INT pin when a Periodic Time Update0̅̅̅̅̅ pin is cancelled. – Default value
event occurs or the tRTN2 - signal on INT
An interrupt signal is generated on ̅̅̅̅̅
INT pin when a Periodic Time Update
1
event occurs. The low-level output signal is automatically cleared after tRTN2= 500 ms (Second update) or tRTN2 = 7.813 ms (Minute update).
Periodic Countdown Timer Interrupt Enable bit(see PERIODIC COUNTDOWN TIMER INTERRUPT FUNCTION)
No interrupt signal is generated on ̅̅̅̅̅
INT pin when a Countdown Timer event0̅̅̅̅̅ pin is cancelled. – Default value
occurs or the tRTN1 - signal on INT
An interrupt signal is generated on ̅̅̅̅̅
INT pin when a Periodic Countdown
1Timer event occurs. The low-level output signal is automatically cleared
after tRTN1 = 122 µs (TD = 00) or tRTN1 = 7.813 ms (TD = 01, 10, 11).
Alarm Interrupt Enable bit (see ALARM INTERRUPT FUNCTION)
̅̅̅̅̅ pin when an Alarm event occurs or
No interrupt signal is generated on INT0
the signal is cancelled on ̅̅̅̅̅
INT pin. – Default value̅̅̅̅̅ pin when an Alarm event occurs.
An interrupt signal is generated on INT
1This setting is retained until the AF flag is cleared to 0 (no automatic
cancellation).
Event Interrupt Enable bit(see EXTERNAL EVENT INTERRUPT FUNCTION and INTERRUPT SCHEME)̅̅̅̅̅ pin when an External Event on EVI
No interrupt signal is generated on INT0
pin occurs or when an Automatic Backup Switchover occurs or the signal
̅̅̅̅̅ pin. – Default value
is cancelled on INT
An interrupt signal is generated on ̅̅̅̅̅
INT pin when an External Event on EVI
pin occurs and TSS = 0, or when an Automatic Backup Switchover occurs
1̅̅̅̅̅ pin is retained until the EVF flag is cleared
and TSS = 1. The signal on INT
to 0 (no automatic cancellation).
12 or 24 hour mode (see CLOCK REGISTERS and ALARM REGISTERS).
The value in the Hours register changes automatically between 12 and 24 hour mode
when 12_24 bit is changed. The value in the Hours Alarm register (08h) however must
be rewritten.
024 hour mode is selected (0 to 23). – Default value
1
12 hour mode is selected (1 to 12).
Reset bit. This bit is used for a software-based time adjustment (synchronization).
(see RESET BIT FUNCTION).
0
No reset. – Default value
Resets the clock prescaler frequencies from 8192 Hz to 1 Hz (writing to theSeconds register has same effect). This bit always returns 0 when read.
An eventual present memorized 1 Hz update is also reset. Because theupper stage of the prescaler is not reset (16.384 kHz) and the I2C interface
1
is asynchronous, the first 1 Hz period after reset will be 0 to 244 µs shorter
than 1 second.
Resetting the prescaler will have an influence on the length of the current
clock period on all subsequent peripherals (clock and calendar, CLKOUT,
timer clock, update timer clock, UNIX clock, EVI input filter).
24/116
Rev. 1.4

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Extreme Low Power Real-Time Clock Module

RV-3028-C7

11h – GP Bits
This register holds the bits for general purpose use (7 bits).
Read: Always readable. Write: Can be write-protected by password.
Address

Function

Conv.

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

11h

GP Bits
Reset

R/WP

0

GP6
0

GP5
0

GP4
0

GP3
0

GP2
0

GP1
0

GP0
0

Bit

Symbol

Value

7
6:0

GPx

0
0 or 1

Description
Bit not implemented. Will return a 0 when read.
Register bits for general purpose use (7 bits).

12h – Clock Interrupt Mask
This register is used to select a predefined interrupt for automatic clock output. Setting a bit to 1 selects thecorresponding interrupt. Multiple interrupts can be selected. After power on, no interrupt is selected (see CLOCKOUTPUT SCHEME).
Read: Always readable. Write: Can be write-protected by password.
Address12hFunction
Clock Interrupt
Mask
Reset

Bit

Symbol

7:4

-

3

CEIE

2

CAIE

1

CTIE

0

CUIE

November 2021

Conv.

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

R/WP

-

-

-

-

CEIE

CAIE

CTIE

CUIE

0

0

0

0

0

0

0

0

Value

Description0

Bit not implemented. Will return a 0 when read.
Clock output when Event Interrupt bit.
The source for the Event Interrupt can be the External Event from EVI pin or theAutomatic Backup Switchover (see INTERRUPT SCHEME).
0Disabled – Default value
1
Enabled. Internal signal EI is selected.
Clock output when Alarm Interrupt bit.
0
Disabled – Default value
1
Enabled. Internal signal AI is selected.
Clock output when Periodic Countdown Timer Interrupt bit.
0
Disabled – Default value
1
Enabled: Internal signal TI is selected.
Clock output when Periodic Time Update Interrupt bit.
0
Disabled – Default value
1
Enabled. Internal signal UI is selected.

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Extreme Low Power Real-Time Clock Module

RV-3028-C7

3.8. EVENT CONTROL REGISTER
13h – Event Control
This register controls the event detection on the EVI pin. Depending of the EHL bit, high or low level (or rising or
falling edge) can be detected. Moreover a digital glitch filtering can be applied to the EVI signal by selecting asampling period tSP in the ET field. Furthermore this register holds control functions for the Time Stamp data. And
the switching over to VBACKUP Power state can be selected as source for an event.
Read: Always readable. Write: Can be write-protected by password.
Address

Function

Conv.

Bit 7

Bit 6

Bit 5

13h

Event Control
Reset

R/WP

○
0

EHL
0

0

Bit

Symbol

7

○

6

EHL

5:4

ET

3

○

2

TSR

1

TSOW

0

TSS

November 2021

Value

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

0

○
0

TSR
0

TSOW
0

TSS
0

ET

Description

0

Read only. Always 0.
Event High/Low Level (Rising/Falling Edge) selection for detection(see EXTERNAL EVENT INTERRUPT FUNCTION)
The falling edge (ET = 00) or low level (ET ≠ 00) is regarded as the0External Event on pin EVI. – Default value
The rising edge (ET = 00) or high level (ET ≠ 00) is regarded as the1External Event on pin EVI.
Event Filtering Time set.
Applies a digital filtering to the EVI pin by sampling the EVI signal.
(see EXTERNAL EVENT INTERRUPT FUNCTION).
00
No filtering. Edge detection. – Default value
01
Sampling period tSP = 3.9 ms (256 Hz). Level detection.
10
Sampling period tSP = 15.6 ms (64 Hz). Level detection.
11
Sampling period tSP = 125 ms (8 Hz). Level detection.
0
Read only. Always 0.
Time Stamp Reset bit (see TIME STAMP FUNCTION)
0
Disables the Time Stamp Reset. – Default value
Resets all seven time stamp registers (Count TS to Year TS) to 00h; this1
bit always returns 0 when read.
Time Stamp Overwrite bit. Controls the overwrite function of the TS registers(Seconds TS to Year TS). The counter Count TS is always working, independent of
the settings of the overwrite bit TSOW.
(see TIME STAMP FUNCTION)
The time stamp of the first occurred event is recorded and remains in TS
0registers. To initialize or reinitialize the first event detection function, the
EVF has to be cleared. – Default value
The time stamp of the last occurred event is recorded and TS registers are1
overwritten. The EVF flag does not need to be cleared.
Time Stamp Source Selection bit (see TIME STAMP FUNCTION)
External Event is selected as Time Stamp source.
0
A time stamp is generated (when TSE = 1) and an interrupt is issued(when EIE = 1) when an External Event on EVI pin occurs – Default value
Automatic Backup Switchover is selected as Time Stamp source.
1
A time stamp is generated (when TSE = 1) and an Interrupt is issued(when BSIE = 1) when the circuit goes to VBACKUP Power state.

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Extreme Low Power Real-Time Clock Module

RV-3028-C7

3.9. TIME STAMP REGISTERS
Seven Time Stamp registers (Count TS to Year TS), (see TIME STAMP FUNCTION).
14h – Count TS
This register contains the number of occurrences of the corresponding event in standard binary format. The values
range from 0 to 255.
Read only. Writing to this register has no effect.
Address

Function

Conv.

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

14h

Count TS
Reset

R

128
0

64
0

32
0

16
0

8
0

4
0

2
0

1
0

Bit

SymbolValue

7:0

Count TS0 to 255

Description
Number of occurrences of the corresponding event, coded in binary. In
case of an overflow the counter starts again with 00hWhen bit TSE = 0, the counter stops counting events.
When bit TSE = 1, the counter is increased when event occurs.
The counter Count TS is always working, independent of the settings ofthe overwrite bit TSOW.
The Count TS register is reset to 00h when 1 is written to the Time Stamp
Reset bit TSR (see TIME STAMP FUNCTION).

15h – Seconds TS
This register holds a recorded Time Stamp of the Seconds register, in two binary coded decimal (BCD) digits. The
values are from 00 to 59.
Read only. Writing to this register has no effect.
Address

Function

Conv.

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

15h

Seconds TS
Reset

R

○
0

40
0

20
0

10
0

8
0

4
0

2
0

1
0

Bit

Symbol7○

6:0

Seconds TS

Value
0

00 to 59

Description
Read only. Always 0.
Holds a recorded Time Stamp of the Seconds register, coded in BCD
format. When enabled (bit TSE = 1), Depending on the setting of the
TSOW bit it contains the time stamp of the first or last occurred event.
The Seconds TS register is reset to 00h when 1 is written to the Time
Stamp Reset bit TSR.

16h – Minutes TS
This register holds a recorded Time Stamp of the Minutes register, in two binary coded decimal (BCD) digits. The
values are from 00 to 59.
Read only. Writing to this register has no effect.
Address

Function

Conv.

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

16h

Minutes TS
Reset

R

○
0

40
0

20
0

10
0

8
0

4
0

2
0

1
0

Bit

Symbol7○

6:0

Minutes TS

November 2021

Value
0

00 to 59

Description
Read only. Always 0.
Holds a recorded Time Stamp of the Minutes register, coded in BCD
format. When enabled (bit TSE = 1), Depending on the setting of the
TSOW bit it contains the time stamp of the first or last occurred event.
The Minutes TS register is reset to 00h when 1 is written to the Time
Stamp Reset bit TSR.

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Extreme Low Power Real-Time Clock Module

RV-3028-C7

17h – Hours TS
This register holds a recorded Time Stamp of the Hours register, in two binary coded decimal (BCD) digits. If the
12_24 bit is cleared (default) (see STATUS AND CONTROL REGISTERS, 10h – Control 2) the values will be from0 to 23. If the 12_24 bit is set, the hour values will range from 1 to 12 and the AMPM bit will be 0 for AM hours and 1
for PM hours.
Read only. Writing to this register has no effect.
Address17hFunction
Hours TS(24 hour mode)– default value
Hours TS(12 hour mode)
Reset

Conv.

Bit 7

Bit 6

R

○

○

0

0

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

20

10

8

4

2

1

AMPM

10

8

4

2

1

0

0

0

0

0

0

Hours TS (24 hour mode) – default value
Bit

Symbol

7:6

○

5:0

Hours TS (24 hour mode)– default value

Value

Description

0

Read only. Always 0.
Holds a recorded Time Stamp of the Hours register, coded in BCD format.
When enabled (bit TSE = 1), Depending on the setting of the TSOW bit itcontains the time stamp of the first or last occurred event.
The Hours TS register is reset to 00h when 1 is written to the Time Stamp
Reset bit TSR.

0 to 23

Hours TS (12 hour mode)
Bit

Symbol

7:6

○

5

AMPM

4:0

Hours TS (12 hour mode)

Value

Description001

Read only. Always 0.
AM hours, from the recorded Time Stamp of the Hours register.
PM hours, from the recorded Time Stamp of the Hours register.
Holds a recorded Time Stamp of the Hours register, coded in BCD format.
When enabled (bit TSE = 1), Depending on the setting of the TSOW bit itcontains the time stamp of the first or last occurred event.
The Hours TS register is reset to 00h when 1 is written to the Time Stamp
Reset bit TSR.

1 to 1218h – Date TS
This register holds a recorded Time Stamp of the Date register, in two binary coded decimal (BCD) digits. The values
will range from 01 to 31.
Read only. Writing to this register has no effect.
Address

Function

Conv.

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

18h

Date TS
Reset

R

○
0

○
0

20
0

10
0

8
0

4
0

2
0

1
0

Bit

Symbol

7:6

○

5:0

Date TS

November 2021

Value

Description

0

Read only. Always 0.
Holds a recorded Time Stamp of the Date register, coded in BCD format.
When enabled (bit TSE = 1), Depending on the setting of the TSOW bit itcontains the time stamp of the first or last occurred event.
The Date TS register is reset to 00h when 1 is written to the Time Stamp
Reset bit TSR.
After POR or when reset with TSR bit and when a Time Stamp is recorded,
the value 00 will be replaced by a valid value (01 to 31).

01 to 31

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Extreme Low Power Real-Time Clock Module

RV-3028-C7

19h – Month TS
This register holds a recorded Time Stamp of the Month register, in two binary coded decimal (BCD) digits. The
values will range from 01 to 12.
Read only. Writing to this register has no effect.
Address

Function

Conv.

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

19h

Month TS
Reset

R

○
0

○
0

○
0

10
0

8
0

4
0

2
0

1
0

Bit

Symbol

7:5

○

4:0

Month TS

Value

Description

0

Read only. Always 0.
Holds a recorded Time Stamp of the Month register, coded in BCD format.
When enabled (bit TSE = 1), Depending on the setting of the TSOW bit itcontains the time stamp of the first or last occurred event.
The Month TS register is reset to 00h when 1 is written to the Time Stamp
Reset bit TSR.
After POR or when reset with TSR bit and when a Time Stamp is recorded,
the value 00 will be replaced by a valid value (01 to 12).

01 to 12

1Ah – Year TS
This register holds a recorded Time Stamp of the Year register, in two binary coded decimal (BCD) digits. Values will
range from 00 to 99.
Read only. Writing to this register has no effect.
Address

Function

Conv.

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

1Ah

Year TS
Reset

R

80
0

40
0

20
0

10
0

8
0

4
0

2
0

1
0

Bit

SymbolValue

7:0

Year TS

00 to 99

November 2021

Description
Holds a recorded Time Stamp of the Year register, coded in BCD format.
When enabled (bit TSE = 1), Depending on the setting of the TSOW bit itcontains the time stamp of the first or last occurred event.
The Year TS register is reset to 00h when 1 is written to the Time Stamp
Reset bit TSR.

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Extreme Low Power Real-Time Clock Module

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3.10. UNIX TIME REGISTERS
The UNIX Time counter is a 32-bit counter with the value in binary format. The counter will roll-over to 00000000h
when reaching FFFFFFFFh. The 4 counter registers are fully readable and writable. The counter source clock is thedigitally offset compensated 1 Hz clock frequency. The UNIX Time counter increment is inhibited during I2C write
access to the 4 UNIX Time registers to allow coherent data values (see UNIX TIME COUNTER and SETTING ANDREADING THE TIME).
Read: Always readable. Write: Can be write-protected by password.
1Bh – UNIX Time 0
Bit 0 to 7 from 32-bit UNIX Time counter.
Address

Function

Conv.

1Bh

UNIX Time 0
Reset

R/WP

Bit

Symbol7:0UNIX 0 [7:0]

Bit 7
0
Value
00h to
FFh

Bit 6
0

Bit 5
0

Bit 4

Bit 3

UNIX 0 [7:0]
0
0

Bit 2

Bit 1

Bit 0

0

0

0

Bit 2

Bit 1

Bit 0

0

0

0

Bit 2

Bit 1

Bit 0

0

0

0

Bit 2

Bit 1

Bit 0

0

0

0

Description
Bit 0 to 7 from 32-bit UNIX counter.

1Ch – UNIX Time 1
Bit 8 to 15 from 32-bit UNIX Time counter.
Address

Function

Conv.

1Ch

UNIX Time 1
Reset

R/WP

Bit

Symbol7:0UNIX 1 [15:8]

Bit 7
0
Value
00h to
FFh

Bit 6
0

Bit 5
0

Bit 4

Bit 3

UNIX 1 [15:8]
00
Description

Bit 8 to 15 from 32-bit UNIX counter.

1Dh – UNIX Time 2
Bit 16 to 23 from 32-bit UNIX Time counter.
Address

Function

Conv.

1Dh

UNIX Time 2
Reset

R/WP

Bit

Symbol7:0UNIX 2 [23:16]

Bit 7
0
Value
00h to
FFh

Bit 6
0

Bit 5
0

Bit 4

Bit 3

UNIX 2 [23:16]
00
Description

Bit 16 to 23 from 32-bit UNIX counter.

1Eh – UNIX Time 3
Bit 24 to 31 from 32-bit UNIX Time counter.
Address

Function

Conv.

1Eh

UNIX Time 3
Reset

R/WP

Bit

Symbol7:0UNIX 3 [31:24]

November 2021

Bit 7
0
Value
00h to
FFh

Bit 6
0

Bit 5
0

Bit 4

Bit 3

UNIX 3 [31:24]
00
Description

Bit 24 to 31 from 32-bit UNIX counter.

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Extreme Low Power Real-Time Clock Module

RV-3028-C7

3.11. RAM REGISTERS
Two free RAM bytes, which can be used for any purpose, for example, status bytes of the system.
1Fh – User RAM 1
This register holds the bits for general purpose use.
Read: Always readable. Write: Can be write-protected by password.
Address

Function

Conv.

1Fh

User RAM 1
Reset

R/WP

Bit

Symbol

7:0

RAM 1

Bit 7

Bit 6

Bit 5

Bit 4

0

0

0

0

Bit 3

Bit 2

Bit 1

Bit 0

0

0

0

Bit 2

Bit 1

Bit 0

0

0

0

RAM 1

Value
00h toFFh0
Description

RAM 1 data

20h – User RAM 2This register holds the bits for general purpose use.
Read: Always readable. Write: Can be write-protected by password.
Address

Function

Conv.

20h

User RAM 2
Reset

R/WP

Bit

Symbol

7:0

RAM 2

November 2021

Bit 7

Bit 6

Bit 5

Bit 4

0

0

0

0

Bit 3

RAM 2

Value
00h toFFh0
Description

RAM 2 data

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Extreme Low Power Real-Time Clock Module

RV-3028-C7

3.12. PASSWORD REGISTERS
After a Power up and the first refreshment time tPREFR = ~66 ms, the Password PW registers are reset to 00h.
When enabled by writing 255 into the EEPROM Password Enable register EEPWE (EEPROM 30h) the Password
PW registers are used to be written with the 32-Bit Password necessary to be able to write in all writable registers
that have the convention WP (time, control, user RAM, configuration EEPROM and user EEPROM registers). The
32-Bit Password PW is compared to the 32 bits stored in the RAM mirror of the EEPROM Password EEPW (seeEEPROM PASSWORD REGISTERS).
21h – Password 0
Bit 0 to 7 from 32-bit Password.
Write only. Returns 0 when read.
Address

Function

Conv.

21h

Password 0
Reset

W

Bit

Symbol

7:0

PW 0 [7:0]

Bit 7
0
Value
00h to
FFh

Bit 6
0

Bit 5
0

Bit 4

Bit 3

PW 0 [7:0]
0
0

Bit 2

Bit 1

Bit 0

0

0

0

Bit 2

Bit 1

Bit 0

0

0

0

Bit 2

Bit 1

Bit 0

0

0

0

Bit 2

Bit 1

Bit 0

0

0

0

Description
Bit 0 to 7 from 32-bit Password

22h – Password 1
Bit 8 to 15 from 32-bit Password.
Write only. Returns 0 when read.
Address

Function

Conv.

22h

Password 1
Reset

W

Bit

Symbol

7:0

PW 1 [15:8]

Bit 7

Bit 6

Bit 5

0

0

0

Value
00h to
FFh

Bit 4

Bit 3

PW 1 [15:8]
00
Description

Bit 8 to 15 from 32-bit Password

23h – Password 2
Bit 16 to 23 from 32-bit Password.
Write only. Returns 0 when read.
Address

Function

Conv.

23h

Password 2
Reset

W

Bit

Symbol

7:0

PW 2 [23:16]

Bit 7

Bit 6

Bit 5

0

0

0

Value
00h to
FFh

Bit 4

Bit 3

PW 2 [23:16]
00
Description

Bit 16 to 23 from 32-bit Password

24h – Password 3
Bit 24 to 31 from 32-bit Password.
Write only. Returns 0 when read.
Address

Function

Conv.

24h

Password 3
Reset

W

Bit

Symbol

7:0

PW 3 [31:24]

November 2021

Bit 7
0
Value
00h to
FFh

Bit 6
0

Bit 5
0

Bit 4

Bit 3

PW 3 [31:24]
00
Description

Bit 24 to 31 from 32-bit Password

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Extreme Low Power Real-Time Clock Module

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3.13. EEPROM MEMORY CONTROL REGISTERS
See also EEPROM READ/WRITE.
25h – EE AddressThis register holds the Address used for read or write from/to a single EEPROM Memory byte.
Read: Always readable. Write: Can be write-protected by password.
Address

Function

Conv.

25h

EE Address
Reset

R/WP

Bit

Symbol7:0

EEADDR

Bit 7

Bit 6

Bit 5

Bit 4

0

0

0

0

Bit 3

Bit 2

Bit 1

Bit 0

0

0

0

EEADDRValue
00h toFFh0
Description

Address for direct read or write one EEPROM Memory byte.

26h – EE Data
This register holds the Data that are read from, or that are written to a single EEPROM Memory byte.
Read: Always readable. Write: Can be write-protected by password.
Address

Function

Conv.

26h

EE Data
Reset

R/WP

Bit

Symbol

7:0

EEDATA

November 2021

Bit 7

Bit 6

Bit 5

Bit 4

X

X

X

X

Bit 3

Bit 2

Bit 1

Bit 0

X

X

X

EEDATAValue
00h toFFh

X
Description

Data from direct read or for direct write to one EEPROM Memory byte.

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Extreme Low Power Real-Time Clock Module

RV-3028-C7

27h – EE Command
This register must be written with specific values, in order to Update or Refresh all (readable/writeable) Configuration
EEPROM registers or to read or write from/to a single EEPROM Memory byte.
Before using this commands, the automatic refresh function has to be disabled (EERD = 1) and the busy status bit
EEbusy has to indicate, that the last transfer has been finished (EEbusy = 0). Before entering the command 11h,
12h, 21h or 22h, EECMD has to be written with 00h.
Write only. Can be write-protected by password.
Address

Function

Conv.

27h

EE Command
Reset

WP

Bit

Symbol

Bit 7

Bit 6

Bit 5

Bit 4

0

0

0

0

Value

11h

12h
EECMD

21h

22h

November 2021

Bit 2

Bit 1

Bit 0

0

0

0

EECMD

00h

7:0

Bit 3
0
Description

Commands for EEPROM Memory (see EEPROM READ/WRITE)First command must be 00h. – Default value
UPDATE (ALL CONFIGURATION RAM  EEPROM).
When writing a value of 11h, data from all Configuration RAM mirror bytes(address 30h to 37h) are written (stored) into the corresponding
Configuration EEPROM bytes. See also USE OF THE CONFIGURATIONREGISTERS.
REFRESH (ALL CONFIGURATION EEPROM  RAM).
When writing a value of 12h, data from all Configuration EEPROM bytes
are read and copied into the corresponding Configuration RAM mirror
bytes (address 30h to 37h). Functions become active as soon as the RAM
bytes are written.
WRITE TO ONE EEPROM BYTE (EEDATA (RAM)  EEPROM).
When writing a value of 21h, data from the EEDATA (RAM) byte are
written (stored) into the EEPROM byte with the address specified in the
EEADDR byte. For Configuration EEPROM (address 30h to 37h) and User
EEPROM (address 00h to2Ah).
READ ONE EEPROM BYTE (EEPROM  EEDATA (RAM)).
When writing a value of 22h, data from the EEPROM byte with the address
specified in EEADDR byte are read and copied into the EEDATA (RAM)byte. For Configuration EEPROM (address 30h to 37h) and User EEPROM(address 00h to2Ah).

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Extreme Low Power Real-Time Clock Module

RV-3028-C7

3.14. ID REGISTER
28h – ID
This register holds the 4 bit Hardware Identification number (HID) and the 4 bit Version Identification number (VID).
The ID can be used to monitor a hardware modification and the version in the production line.
Read only. Writing to this register has no effect.
Address

Function

Conv.

Bit 7

28h

ID
Reset

R

Bit

Symbol

Value

7:4
3:0

HID
VID

0 to 15
0 to 15

Bit 6

Bit 5

Bit 4

Bit 3

HID
Preconfigured Value

Bit 2

Bit 1

Bit 0

VID
Preconfigured Value
Description

Hardware Identification number.
Version Identification number.

3.15. CONFIGURATION EEPROM WITH RAM MIRROR REGISTERS
All Configuration EEPROM at addresses 2Bh and 30h to 37h are memorized in the EEPROM and mirrored in theRAM. Functions become active as soon as the RAM mirror bytes are written. See also USE OF THE
CONFIGURATION REGISTERS.

3.15.1. EEPROM RESERVED
2Bh – EEPROM RESERVEDThis preconfigured (Factory Calibrated) value must not be overwritten.
Read: Always readable. Write: Can be write-protected by password.
Address2BhFunction

Conv.

Bit 7

Bit 6

EEPROM
R/WP
Reserved
Default value on delivery

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

RESERVED (Must not be overwritten)
Preconfigured (Factory Calibrated)

Bit

SymbolValue

7:0

RESERVED

Preconfigured (Factory Calibrated) – Must not be overwritten.

Description

3.15.2. EEPROM PASSWORD ENABLE REGISTER
After a Power up and the first refreshment time tPREFR = ~66 ms, the Password Enable value EEPWE is copied fromthe EEPROM to the corresponding RAM mirror. The default value preset on delivery is 00h.
30h – EEPROM Password Enable
Read: Always readable. Write: Can be write-protected by password.
Address30h
BitFunction

Conv.

EEPROM
R/WP
Password Enable
Default value on delivery
Symbol

Bit 7

Bit 6

Bit 5

Bit 4

0

0

0

0

Value

EEPWE
255

November 2021

Bit 2

Bit 1

Bit 0

0

0

0

EEPWE

0 to 254
7:0

Bit 3

0
Description

EEPROM Password Enable
Password function disabled.
When writing a value not equal 255, the password function is disabled.
– 00h is the default value preset on delivery
Password function enabled.
When writing a value of 255, the Password registers (21h to 24h) can beused to enter the 32-bit Password.

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Extreme Low Power Real-Time Clock Module

RV-3028-C7

3.15.3. EEPROM PASSWORD REGISTERS
After a Power up and the first refreshment time tPREFR = ~66 ms, the EEPROM Password registers 0 to 3 with the 32bit EEPROM Password are copied from the EEPROM to the corresponding RAM mirror. The default values preseton delivery are 00h.
31h – EEPROM Password 0
Bit 0 to 7 from 32-bit EEPROM Password.
RAM mirror is Write only. Returns 0 when read. EEPROM can be READ when Unlocked.
Address31h
BitFunction

Conv.

EEPROM
*WP
Password 0
Default value on delivery

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

0

0

0

Bit 2

Bit 1

Bit 0

0

0

0

Bit 2

Bit 1

Bit 0

0

0

0

Bit 2

Bit 1

Bit 0

0

0

0

EEPW 0 [7:0]
0

0

0

0

0

SymbolValue
Description
00h to
7:0
EEPW 0 [7:0]
Bit 0 to 7 from 32-bit EEPROM Password
FFh* EEPW registers: RAM mirror is Write only. Returns 0 when read. EEPROM can be READ when Unlocked.

32h – EEPROM Password 1
Bit 8 to 15 from 32-bit EEPROM Password.
RAM mirror is Write only. Returns 0 when read. EEPROM can be READ when Unlocked.
Address32h
BitFunction

Conv.

EEPROM
*WP
Password 1
Default value on delivery

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

EEPW 1 [15:8]
0

0

0

0

0

SymbolValue
Description
00h to
7:0
EEPW 1 [15:8]
Bit 8 to 15 from 32-bit EEPROM Password
FFh* EEPW registers: RAM mirror is Write only. Returns 0 when read. EEPROM can be READ when Unlocked.

33h – EEPROM Password 2
Bit 16 to 23 from 32-bit EEPROM Password.
RAM mirror is Write only. Returns 0 when read. EEPROM can be READ when Unlocked.
Address33h
BitFunction

Conv.

EEPROM
*WP
Password 2
Default value on delivery

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

EEPW 2 [23:16]
0

0

0

0

0

SymbolValue
Description
00h to
7:0
EEPW 2 [23:16]
Bit 16 to 23 from 32-bit EEPROM Password
FFh* EEPW registers: RAM mirror is Write only. Returns 0 when read. EEPROM can be READ when Unlocked.

34h – EEPROM Password 3
Bit 24 to 31 from 32-bit EEPROM Password.
RAM mirror is Write only. Returns 0 when read. EEPROM can be READ when Unlocked.
Address34h
BitFunction

Conv.

EEPROM
*WP
Password 3
Default value on delivery

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

EEPW 3 [31:24]
0

0

0

0

0

Value
Description
00h to
7:0
EEPW 3 [31:24]
Bit 24 to 31 from 32-bit EEPROM Password
FFh* EEPW registers: RAM mirror is Write only. Returns 0 when read. EEPROM can be READ when Unlocked.
November 2021

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Micro Crystal
Extreme Low Power Real-Time Clock Module

RV-3028-C7

3.15.4. EEPROM CLKOUT REGISTER
35h – EEPROM Clkout
A programmable square wave output is available at CLKOUT pin. Clock output can be controlled by the CLKOE bit(or by the CLKF flag) (see PROGRAMMABLE CLOCK OUTPUT). After a Power up and the first refreshment time
tPREFR = ~66 ms, the EEPROM Clkout values CLKOE, CLKSY, PORIE and FD are copied from the EEPROM to thecorresponding RAM mirror. The default values preset on delivery are: CLKOUT = enabled, synchronization enabled,
F = 32.768 kHz.
Read: Always readable. Write: Can be write-protected by password.
Address

Function

Conv.

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

35h

EEPROM Clkout
R/WP
Default value on delivery

CLKOE
1

CLKSY
1

0

0

PORIE
0

Bit

Symbol

Value

7

CLKOE

6

CLKSY

5:4

-

3

PORIE

2:0

FD

FD value
000
001
010
011
100
101
110
111

Bit 2

Bit 1

Bit 0

0

FD
0

0

Description

CLKOUT Enable bit (see PROGRAMMABLE CLOCK OUTPUT)
The CLKOUT pin is LOW (if CLKF flag is 0).
The clock output signal on CLKOUT pin is enabled. – Default value on
1
delivery
CLKOUT Synchronized enable/disable (see SYNCHRONIZED ENABLE/DISABLE)0
Disabled
Enables the Synchronized enable/disable (by CLKOE bit or CLKF flag) of1
the CLKOUT frequency. – Default value on delivery0
Bit not implemented. Will return a 0 when read.
Power On Reset Interrupt Enable bit(see POWER ON RESET INTERRUPT FUNCTION)
̅̅̅̅̅ pin when a Power On Reset occurs
No interrupt signal is generated on INT0or the signal is cancelled on ̅̅̅̅̅
INT pin. – Default value on delivery
An interrupt signal is generated on ̅̅̅̅̅
INT pin when a Power On Reset occurs.
1This setting is retained until the PORF flag is cleared to 0 (no automatic
cancellation).
000 to
CLKOUT Frequency Selection (see CLKOUT FREQUENCY SELECTION)
111
0

CLKOUT Frequency Selection
32.768 kHz – Default value on delivery
8192 Hz (1)1024 Hz (1)64 Hz (1)32 Hz (1)1 Hz (1)Predefined periodic countdown timer interrupt (1) (2)
CLKOUT = LOW

Effect when writing 1 to the RESET bit or whenwriting to the Seconds registerNo effect
Affects current period
Affects current period
Affects current period
Affects current period
Affects current period
Affects current period
No effect(1) 8192 Hz to 1 Hz clock pulses and the timer interrupt pulses can be affected by compensation pulses(see FREQUENCY OFFSET CORRECTION).
(2) CLKSY bit has no effect.

November 2021

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Extreme Low Power Real-Time Clock Module

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3.15.5. EEPROM OFFSET REGISTER
The registers EEPROM Offset and EEPROM Backup hold the EEOffset value to digitally compensate the initialfrequency deviation of the 32.768 kHz oscillator or for aging adjustment. EEOffset defines correction pulses in steps.
Each pulse introduces a deviation of 0.9537 ppm, the maximum range is from +243.2 ppm to -244.1 ppm. The valueof 0.9537 ppm is based on a nominal 32.768 kHz clock (see FREQUENCY OFFSET CORRECTION). The
preconfigured (Factory Calibrated) EEOffset value may be changed by the user.
36h – EEPROM Offset
This register holds the upper 8 bits of the EEOffset value. The preconfigured (Factory Calibrated) EEOffset value
may be changed by the user. The least significant bit (LSB) of the EEOffset value is located in register EEPROM
Backup (37h) (see also EEPROM BACKUP REGISTER).
After a Power up and the first refreshment time tPREFR = ~66 ms, the EEPROM Offset value is copied from the
EEPROM to the corresponding RAM mirror.
Read: Always readable. Write: Can be write-protected by password.
Address

Function

Conv.

36h

EEPROM Offset
R/WP
Default value on delivery

Bit

Symbol

7:0

EEOffset [8:1]

Address

Bit 7

Conv.

EEPROM Backup

R/WP

37h
Default value on delivery

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

Bit 1

Bit 0

EEOffset [8:1]
Preconfigured (Factory Calibrated)
Value
00h toFFhFunction

Bit 6

Bit 7
EEOffset[0]
Preconfigured

Description
Upper 8 bits of the EEOffset value. See table below.

Bit 6

Bit 5

Bit 4

BSIE

TCE

FEDE

0

0

1

Bit 3

Bit 2
BSM

0

TCR
0

Bit

SymbolValue

Description

7

EEOffset [0]0 or 1LSB of the EEOffset value. See table below.

00EEOffset (9 bits):
EEOffset [8:0]

EEOffset correction value indecimalCorrection pulses
in steps

011111111
011111110:
000000001
000000000

255
254
:
1
0

255
254
:
1
0

CLKOUT frequency correctionin ppm(*)
243.187242.233
:
0.954
0.000

111111111
111111110:
100000001
100000000

511
510
:
257
256

-1
-2
:
-255
-256

-0.954-1.907:-243.187-244.141(*) Each correction pulse corresponds to 1 / (16384 × 64) = 0.9537 ppm.

The frequency deviation measured at CLKOUT pin can be compensated by computing the correction value EEOffset and writing it
into the EEPROM Offset and EEPROM Backup registers (see FREQUENCY OFFSET CORRECTION).

November 2021

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Extreme Low Power Real-Time Clock Module

RV-3028-C7

3.15.6. EEPROM BACKUP REGISTER
37h – EEPROM Backup
This register is used to control the switchover function and the trickle charger and it holds bit 0 (LSB) of the EEOffset
value. The preconfigured (Factory Calibrated) EEOffset value may be changed by the user.
After a Power up and the first refreshment time tPREFR = ~66 ms, the EEPROM Backup value is copied from the
EEPROM to the corresponding RAM mirror.
Read: Always readable. Write: Can be write-protected by password.
Address

Function
EEPROM Backup

Conv.
R/WP

37h
Default value on delivery

Bit 7
EEOffset[0]
Preconfigured

Bit

SymbolValue

7

EEOffset [0]0 to 1

6

BSIE

5

TCE

4

FEDE

3:2

BSM

1:0

TCR

November 2021

Bit 6

Bit 5

Bit 4

BSIE

TCE

FEDE

0

0

1

Bit 3

Bit 2

Bit 1

BSM
0

Bit 0
TCR

0

0

0

Description

LSB of the EEOffset value (see EEPROM OFFSET REGISTER).
Backup Switchover Interrupt Enable bit(see AUTOMATIC BACKUP SWITCHOVER FUNCTION and
AUTOMATIC BACKUP SWITCHOVER INTERRUPT FUNCTION)
̅̅̅̅̅ pin when an Automatic Backup
No interrupt signal is generated on INT0
Switchover occurs or the signal is cancelled on ̅̅̅̅̅
INT pin. – Default value ondelivery̅̅̅̅̅ pin when an Automatic Backup
An interrupt signal is generated on INT
1
Switchover occurs. This setting is retained until the BSF flag is cleared to 0
(no automatic cancellation).
Trickle Charger Enable bit (see TRICKLE CHARGER)
0Disabled – Default value on delivery
1EnabledFast Edge Detection Enable bit(see AUTOMATIC BACKUP SWITCHOVER FUNCTION and
AUTOMATIC BACKUP SWITCHOVER INTERRUPT FUNCTION)
0
Disabled.
FEDE should always be set to 1.
When the FEDE bit is 1, the Fast Edge Detection for the Automatic Backup
Switchover function is enabled. A voltage on VDD power supply pin with an
1
increasing or falling edge with a slew rate typically greater than 7 V/ms canbe correctly detected and the Automatic Backup Switchover function isadapted to this particular situation. – Default value on delivery
Backup Switchover Mode(see AUTOMATIC BACKUP SWITCHOVER FUNCTION and
AUTOMATIC BACKUP SWITCHOVER INTERRUPT FUNCTION)
To read/write from/to the EEPROM, the user has to disable the Backup Switchover
function by setting the BSM field to 00 or 10 (see routine in EEPROM READ/WRITECONDITIONS)
00
Switchover Disabled. – Default value on delivery
Enables the Direct Switching Mode (DSM).
01
Switchover when VDD < VBACKUP.
10
Switchover Disabled.
Enables the Level Switching Mode (LSM).
11
Switchover when VDD < VTH:LSM (2.0 V) AND VBACKUP > VTH:LSM (2.0 V).
Trickle Charger Series Resistance (see TRICKLE CHARGER)00
TCR 3 kΩ – Default value on delivery01
TCR 5 kΩ10
TCR 9 kΩ11
TCR 15 kΩ

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Extreme Low Power Real-Time Clock Module

RV-3028-C7

3.16. USER EEPROM
00h – 2Ah – User EEPROM
43 Bytes of User EEPROM for general purpose storage are provided.
Read: Always readable. Write: Can be write-protected by password.
Address

FunctionConv.

00h to 2AhUser EEPROM

R/WP

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

Bit 1

Bit 0

43 Bytes of non-volatile User EEPROM

3.17. RESERVED EEPROM
2Ch – 2Fh and 38h – 3Fh – Reserved EEPROM
Protected. Writing to this register has no effect.
Address
2Ch to 2Fh
38h to 3Fh

November 2021

Function
Reserved
EEPROM
Reserved
EEPROM

Conv.

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Prot.

RESERVEDProt.

RESERVED

40/116

Bit 2

Rev. 1.4

Micro Crystal
Extreme Low Power Real-Time Clock Module

RV-3028-C7

3.18. REGISTER RESET VALUES SUMMARY
Reset values; RAM, Address 00h to 3Fh:
Address
00h
01h
02h
03h
04h
05h
06h
07h
08h
09h
0Ah
0Bh
0Ch
0Dh
0Eh
0Fh
10h
11h
12h
13h
14h
15h
16h
17h
18h
19h
1Ah
1Bh
1Ch
1Dh
1Eh
1Fh
20h
21h
22h
23h
24h
25h
26h
27h
28h
29h and 2Ah
2Ch to 2Fh
38h to 3Fh

Function

Conv.

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

Seconds
Minutes
Hours (24h / 12h)
Weekday
Date
Month
Year
Minutes Alarm
Hours Alarm(24h / 12h)
Weekday Alarm /Date Alarm
Timer Value 0
Timer Value 1
Timer Status 0
Timer Status 1
shadow
StatusControl 1
Control 2
GP Bits
Clock Int. Mask
Event Control
Count TS
Seconds TS
Minutes TS
Hours TS(24h / 12h)
Date TSMonth TSYear TS
UNIX Time 0
UNIX Time 1
UNIX Time 2
UNIX Time 3
User RAM 1
User RAM 2
Password 1
Password 2
Password 3
Password 4
EE Address
EE Data
EE CommandID
RESERVEDRESERVEDRESERVED

R/WP
R/WP
R/WP
R/WP
R/WP
R/WP
R/WP
R/WP

0
0
0
0
0
0
0
1

0
0
0
0
0
0
0
0

0
0
0
0
0
0
0
0

0
0
0
0
0
0
0
0

0
0
0
0
0
0
0
0

0
0
0
0
0
0
0
0

0
0
0
0
0
0
0
0

0
0
0
0
1
1
0
0

R/WP

1

0

0

0

0

0

0

0

R/WP

1

0

0

0

0

0

0

0

R/WP
R/WP
R

0
0
0

0
0
0

0
0
0

0
0
0

0
0
0

0
0
0

0
0
0

0
0
0

R

0

0

0

0

0

0

0

0

R/WP
R/WP
R/WP
R/WP
R/WP
R/WP
R
R
R

10
0
0
0
0
0
0
0
0

0
0
0
0
0
0
0
0
0

0
0
0
0
0
0
0
0
0

01
0
0
0
0
0
0
0
0

0
0
0
0
0
0
0
0
0

0
0
0
0
0
0
0
0
0

0
0
0
0
0
0
0
0
0

1
0
0
0
0
0
0
0
0

R

0

0

0

0

0

0

0

0

R
R
R
R/WP
R/WP
R/WP
R/WP
R/WP
R/WP
W
W
W
W
R/WP
R/WP
WP
R
Prot.
Prot.
Prot.

0
0
0
0
0
0
0
0
0
0
0
0
0
0
X
0

0
0
0
0
0
0
0
0
0
0
0
0
0
0
X
0

0
0
0
0
0
0
0
0
0
0
0
0
0
0
X
0

0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
X
X
0
0
Preconfigured Value

0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
X
X
0
0
Preconfigured Value

0
0
0
0
0
0
0
0
0
0
0
0
0
0
X
0

XXh
XXh
XXh

X = not defined

November 2021

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Rev. 1.4

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Extreme Low Power Real-Time Clock Module

RV-3028-C7

Default values on delivery; Configuration EEPROM with RAM mirror, Address 2Bh and 30h to 37h:
Address
2Bh
30h
31h
32h
33h
34h
35h
36h
37h

Function
EEPROM
Reserved
EEPROM PW
EnableEEPROM
Password 0
EEPROM
Password 1
EEPROM
Password 2
EEPROM
Password 3
EEPROM
ClkoutEEPROM
OffsetEEPROM
Backup

Conv.

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

Preconfigured (Factory Calibrated) – Must not be overwritten.

R/WP
R/WP

0

0

0

0

0

0

0

0

WP

0

0

0

0

0

0

0

0

WP

0

0

0

0

0

0

0

0

WP

0

0

0

0

0

0

0

0

WP

0

0

0

0

0

0

0

0

R/WP

1

1

0

0

0

0

0

0

R/WP

0

0

0

0

0

0

0

0

R/WP

0

0

0

1

0

0

0

0

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

Bit 2

Bit 1

Bit 0

Default values on delivery; User EEPROM, Address 00h to 2Ah:
Address

FunctionConv.

00h to 2AhUser EEPROM(43 Bytes)

R/WP

Bit 7

Bit 6

Bit 5

00h

Default values on delivery; Reserved EEPROM, Address 2Ch to 2Fh and 38h to 3Fh:
Address
2Ch to 2Fh
38h to 3Fh

Function
Reserved
EEPROM
Reserved
EEPROM

Conv.

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Prot.

XXh

Prot.

XXh

X = not defined

November 2021

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Rev. 1.4

Micro Crystal
Extreme Low Power Real-Time Clock Module

RV-3028-C7

RV-3028-C7 reset values after power on (RAM) and default values on delivery (EEPROM):
RAM, reset values:
Time (hh:mm:ss)
Date (YY-MM-DD)
Weekday
Hour mode
Count TSTime TS (hh:mm:ss)
Date TS (YY-MM-DD)
UNIX Time
Alarm function
Timer function
Update function
External Event function

=
=
=
=
=
=
=
=
=
=
=
=

Time Stamp function
EEPROM Memory RefreshInterrupts
EEbusy status bit
UF Flag
EVF Flag
PORF Flag
Int. Controlled Clock
Password
EE Address
EE Data
EE Command
ID
General Purpose Bits
User RAM 1, 2

=
=
=
=
=
=
=
=
=
=
=
=
=
=

00:00:00
00-01-01
0
24 hour mode (0 to 23)
0(read only)
00:00:00 (read only)
00-00-00 (read only)
00000000h
disabled, weekday is selecteddisabled, Timer Clock Frequency = 4096 Hz, Single Mode selected
Second update is selected
Falling edge is regarded as External Event on pin EVI,
first event is recorded
disabled, External Event selected, Time Stamp overwrite disabled,
Time Stamp Reset disabled
enableddisabled
1  0 (1 for the time tPREFR = ~66 ms, then it is cleared to 0 automatically)0  1 (Second update is selected)
01(can be cleared by writing 0 to the bit)disabled, no interrupt selected
00000000h(write only)00hXXh00h (first command) (write only)
Preconfigured Value (read only)0(7 bits)
00h(2 bytes)

Configuration EEPROM with RAM mirror, default values on delivery:
EEPROM Reserved (2Bh) = Preconfigured Value – Must not be overwritten
EEPROM Password Enable = disabled
EEPROM Password= 00000000h (write only)
CLKOUT= enabled, synchronization enabled, F = 32.768 kHz
Power On Reset Interrupt = disabled
EEOffset value= Preconfigured Value (9 bits) (may be changed by the user)
Backup Switchover= disabled, interrupt disabled, Fast Edge Detection enabled
Trickle charger= disabled, TCR 3 kΩ is selected

User EEPROM, default values on delivery:
User EEPROM (43 Bytes) = 00h

Reserved EEPROM, Address 2Ch to 2Fh and 38h to 3Fh, default values on delivery:
Reserved EEPROM= XXh (protected)

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4. DETAILED FUNCTIONAL DESCRIPTION
4.1. POWER ON RESET (POR)
The power on reset (POR) is generated at start-up (see POWER ON AC ELECTRICAL CHARACTERISTICS). All
RAM registers including the Counter Registers are initialized to their reset values and the Configuration EEPROM
registers with the RAM mirror registers are set to their preset default values. At power up a refresh of the RAM mirror
values by the values in the Configuration EEPROM is automatically generated. The time of this first refreshment is
tPREFR = ~66 ms. The EEbusy bit in the Status register (0Eh) can be used to monitor the status of the refreshment(see REGISTER RESET VALUES SUMMARY).
The Power On Reset Flag PORF indicates the occurrence of a voltage drop of the internal power supply voltage
below VPOR threshold needed to cause the generation of the device POR. A PORF value of 1 indicates that thevoltage had dropped below the threshold level VPOR and that the time information is corrupted. The value 1 is retained
until a 0 is written by the user.
When PORIE bit (EEPROM 35h) is set and the PORF flag was cleared beforehand, an interrupt signal on ̅̅̅̅̅
INT pincan be generated when a Power On Reset occurs (see POWER ON RESET INTERRUPT FUNCTION).

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4.2. AUTOMATIC BACKUP SWITCHOVER FUNCTION
Basic Hardware Definitions: The RV-3028-C7 has two power supply pins.
o VDD
is the main power supply input pin.
o VBACKUP is the backup power supply input pin.
 VTH:LSM (typical value 2.0 V) is the backup switchover threshold voltage in Level Switching Mode.
 A debounce logic provides a debounce time tDEB of 122 μs to 183 μs, which will filter VDD oscillation when the
backup switchover will switch back from VBACKUP to VDD. I2C access is possible in VDD Power state after thedebounce time tDEB.
 The FEDE bit (EEPROM 37h) should always be set to 1, so that Fast Edge Detection (≥ 7 V/ms) is always
enabled. – Default value on delivery

Switchover Modes:
The RV-3028-C7 has three backup switchover modes. The desired mode can be selected by the BSM field in the
Configuration EEPROM, see EEPROM BACKUP REGISTER:
 BSM = 00 Switchover disabled (default value on delivery), see SWITCHOVER DISABLED.
 BSM = 01 Direct Switching Mode (DSM): when VDD < VBACKUP, switchover occurs from VDD to VBACKUP
without requiring VDD to drop below VTH:LSM (2.0 V), see DIRECT SWITCHING MODE (DSM).
 BSM = 10 Switchover disabled, see SWITCHOVER DISABLED.
 BSM = 11 Level Switching Mode (LSM): when VDD < VTH:LSM (2.0 V) AND VBACKUP > VTH:LSM (2.0 V),
switchover occurs from VDD to VBACKUP, see LEVEL SWITCHING MODE (LSM).
Function Overview:
When a valid backup switchover condition occurs (Direct or Level Switching Mode) and the internal power supply
switches to the VBACKUP voltage (VBACKUP Power state) the following sequence applies: The Backup Switch Flag BSF is set and, if BSIE bit is 1 (EEPROM 37h), an interrupt will be generated on
INT pin and remains as long as BSF is not cleared to 0. If BSIE is 0 no interrupt will be generated (see
AUTOMATIC BACKUP SWITCHOVER INTERRUPT FUNCTION).
 The I2C-bus interface is automatically disabled (high impedance) and reset.
 EVI input remains active for interrupt generation, interrupt driven clock output and time stamp function
 CLKOUT pin is held LOW during VBACKUP Power state.
 The interrupt output pin INT remains active in VBACKUP Power state for any previously configured interrupt
condition.
 Going into VBACKUP Power state can be used as a time stamp condition (see TIME STAMP FUNCTION).
 The backup switchover condition can also be used to enable the clock output on CLKOUT pin automatically,
when again in VDD Power state (see AUTOMATIC BACKUP SWITCHOVER INTERRUPT FUNCTION).
The Backup Switch Flag BSF can be cleared using the I2C-bus interface as soon as the circuit resumes fromVBACKUP Power state and switched back to VDD.

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4.2.1.SWITCHOVER DISABLED
The switchover function is disabled when BSM field (EEPROM 37h) is set to 00 or 10 (BSM = 00 is the default value
on delivery).
1. Used when only one power supply is available (device is always in VDD Power state). The power supply isapplied on VDD pin and the VBACKUP pin must be tied to VSS with a 10 kΩ resistor. The Backup Switch Flag
BSF is always logic 0.
2. Used when VDD is turned off and VBACKUP is still present and the device must not draw any current from the
backup source (IBACKUP = 0 nA). The backup source on VBACKUP pin is in standby mode until the device ispowered up again from main supply VDD and a switchover mode is selected (see also TYPICAL
CHARACTERISTICS).
When the device is first powered up from the backup supply (V BACKUP) but without a main supply (VDD),
switchover is also disabled and the backup source is automatically in standby mode (IBACKUP = 0 nA).

4.2.2.DIRECT SWITCHING MODE (DSM)
This mode is selected with BSM = 01 (EEPROM 37h).
 If VDD > VBACKUP the internal power supply is VDD.
 If VDD < VBACKUP the internal power supply is VBACKUP.
The Direct Switching Mode is useful in systems where V DD is normally higher than VBACKUP (for example, VDD = 5.0
V, VBACKUP = 3.5 V). If the VDD and VBACKUP values are similar (for example, VDD = 3.3 V, VBACKUP ≥ 3.0 V), the Direct
Switching Mode is not recommended as this can lead to unnecessary switching.
In Direct Switching Mode, the power consumption is reduced compared to the Level Switching Mode (LSM) because
VDD is not monitored and compared to the threshold voltage VTH:LSM = 2.0 V (typical IDD:DSM = 95 nA). See also
OPERATING PARAMETERS and TYPICAL CHARACTERISTICS.
Note that the circuit needs in worst case 2 ms to react when changing from disabled switchover to DSM.
Backup switchover in Direct Switching Mode and Backup Switchover Interrupt enabled, BSIE = 1 (EEPROM 37h):

VDD
VBACKUP

0V
BSF

INT
I2C accessenableddisabled

enabledPower state

VDD Power

VBACKUP PowerVDD PowertDEB

Write operation

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4.2.3.LEVEL SWITCHING MODE (LSM)
This mode is selected with BSM = 11 (EEPROM 37h).
 If VDD > VTH:LSM (2.0 V), the internal power supply is VDD.
 If VDD < VTH:LSM (2.0 V) AND VBACKUP > VTH:LSM (2.0 V), the internal power supply is VBACKUP.
In Level Switching Mode, the power consumption is slightly increased compared to the Direct Switching Mode (DSM)
because VDD is monitored and compared to the threshold voltage VTH:LSM = 2.0 V (typical IDD:LSM = 115 nA). See also
OPERATING PARAMETERS and TYPICAL CHARACTERISTICS.
Note that the circuit needs in worst case 15.625 ms to react when changing from disabled switchover to LSM.
Backup switchover in Level Switching Mode and Backup Switchover Interrupt enabled, BSIE = 1 (EEPROM 37h):

Example 1: VBACKUP > VDD

VBACKUP
VDD

Example 2: VBACKUP < VDD

VBACKUP
VTH:LSM = 2.0 V

0V
BSF

INT
I2C accessenableddisabled

enabledPower state

VDD Power

VBACKUP PowerVDD PowertDEB

Write operation

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4.3. TRICKLE CHARGER
The device supporting the VBACKUP pin include a trickle charging circuit which allows a battery or supercapacitor
connected to the VBACKUP pin to be charged from the power supply connected to the VDD pin. See figure below.
In the register EEPROM 37h the Trickle Charger is enabled with bit TCE (default value on delivery is disabled) andthe series current limiting resistor is selected by the TCR field (default value on delivery is 3 kΩ). A schottky diode,with a typical voltage drop of 0.25 V, is inserted in the charging path.
Trickle Charger:
TCR

00

TCE

VDD

7

0

Schottky
diode

01

3 kΩ
5 kΩ
6

1

10
11

9 kΩ

VBACKUP

15 kΩ

The trickle charger is disabled when the device is in VBACKUP Power state.

4.4. PROGRAMMABLE CLOCK OUTPUT
Six different frequencies or the countdown timer interrupt signal can be output on CLKOUT pin, the signal selection
is done in the FD field (EEPROM 35h).
 32.768 kHz, direct from Xtal oscillator, not offset compensated.
 8192 Hz, 1024 Hz, 64 Hz, 32 Hz, 1 Hz; divided Xtal oscillator frequencies, digitally compensated according
to the oscillator offset value EEOffset (EEPROM 36h and 37h).
 Timer interrupt is controlled by the Countdown Timer Control Registers and the Control 1 register.
The negative edge of the original 32,768 kHz clock signal is used to turn on and off a subsequent selected clock
signal. The negative edge is also used to control the clock signal by flag CLKF, bit CLKOE and the FD field. Wheneverthe clock signal is LOW, it is pulled to VSS.
CLKOUT is tied to VSS in VBACKUP Power state independent of the CLKOUT configuration settings.
The frequency output can be controlled directly via the I 2C-bus interface commands (normal operation) or can beinterrupt driven to allow waking up an external system by supplying a clock.
At POR the synchronization function is active since the bit CLKSY is set to 1 (default), the 32.768 kHz frequency is
output to CLKOUT pin since the bit CLKOE is set to 1 (default) and FD field is set to 000 (default). Hint: These are
the default values on delivery, stored in the Configuration EEPROM with RAM mirror. To customize these POR
values, the user can change the values in the Configuration EEPROM.

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4.4.1.CLKOUT FREQUENCY SELECTION
A programmable square wave is available at pin CLKOUT. Operation is controlled by the FD field (EEPROM 35h).
Frequencies from 32.768 kHz (Default value on delivery) to 1 Hz and countdown timer interrupt can be generated foruse as a system clock, microcontroller clock, input to a charge pump, or for calibration of the crystal oscillator.
Pin CLKOUT is a push-pull output that is enabled at power on (Default value on delivery). CLKOUT can be disabled
by setting CLKOE bit to 0 (if CLKF flag is 0) or by setting FD field to 111. When disabled, the CLKOUT pin is LOW.
The RESET bit function can affect the CLKOUT signal depending on the selected frequency. When writing 1 to the
RESET bit or when writing to the Seconds register and the CLKOUT is enabled, the current period of the frequencies
8192 Hz to 1 Hz are affected (for more details, see RESET BIT FUNCTION).
CLKOUT Frequency Selection:
FD value
000
001
010
011
100
101
110
111

CLKOUT Frequency Selection
32.768 kHz –Default value on delivery
8192 Hz (1)1024 Hz (1)64 Hz (1)32 Hz (1)1 Hz (1)Predefined periodic countdown timer interrupt (1) (2)
CLKOUT = LOW

Effect when writing 1 to the RESET bit or whenwriting to the Seconds registerNo effect
Affects current period
Affects current period
Affects current period
Affects current period
Affects current period
Affects current period
No effect(1) 8192 Hz to 1 Hz clock pulses and the timer interrupt pulses can be affected by correction pulses(see FREQUENCY OFFSET CORRECTION).
(2) CLKSY bit has no effect.

4.4.2.NORMAL CLOCK OUTPUT
Condition: The CLKF flag is 0.
Setting bit CLKOE to 1 will drive the selected frequency on CLKOUT, setting CLKOE to 0 will clear the selected
frequency on CLKOUT. See CLOCK OUTPUT SCHEME.

4.4.3.INTERRUPT CONTROLLED CLOCK OUTPUT
Condition: The CLKOE bit is 0.
Writing 1 to CLKIE the occurrence of the selected interrupt condition allows frequency output on CLKOUT. Thisfunction allows waking up an external system by outputting a clock.
Writing 0 to CLKIE will disable new interrupts from driving frequencies on CLKOUT, but if there is already an active
interrupt driven frequency output (CLKF flag is set), the active frequency output will not be stopped. Writing the CLKF
flag to 0 will clear the flag and frequency output will stop. See CLOCK OUTPUT SCHEME.

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4.4.4.SYNCHRONIZED ENABLE/DISABLE
The enabled Synchronized CLKOUT Enable/Disable function (CLKSY = 1) consists of two sub-functions.
 Synchronized CLKOUT enable (tCKH). For enabling clock output on CLKOUT pin the internal first negative
clock edge of the selected clock source (FD field) is detected after CLKF or CLKOE are set.
 Synchronized CLKOUT disable (tCKL). Clock output on CLKOUT will be disabled at the next negative clockedge of the selected clock source (FD field) after both CLKF and CLKOE are cleared and after the I2C-bus
interface stop condition. When disabled, CLKOUT is tied to VSS.
(CLKF and CLKOE = 0  disable condition  next negative clock edge  CLKOUT driven to VSS)
Synchronized CLKOUT Enable/Disable times (CLKSY = 1):
Selected clock(FD field)
enable/disable

CLKOUT
tCKL

tCKH

Selected clock(FD field)
enable/disable

CLKOUT
tCKH

tCKL

Write operation

Hint: Glitch free frequency change on CLKOUT requires clearing flag CLKF and bit CLKOE to 0 before the new clock
is selected in FD field.
(CLKF and CLKOE = 0  disable condition  next negative clock edge  CLKOUT driven to VSS  FD field selection
 CLKF and/or CLKOE = 1  enable condition  next negative clock edge)

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4.4.5.CLOCK OUTPUT SCHEME
Frequency output scheme:
CUIE

CLKIE

0

0

1

1

UI
(1)

CLOCK FLAG
CLKF
SET

to interface:read CLKF

CLKSY

CLEAR
CTIE

from interface:clear CLKF

CLKOE

OR
1

0
1
(2)

0
TI
(1)

1 (2)

1
1
CAIE

FD

0

AI
(1)

1
CEIE
0

EI
(1)

1

0

OR
1

ENABLE/DISABLESYNCHRONIZERDISABLE(2) 32.768 kHz
8192 Hz1024 Hz
64 Hz
32 Hz
1 Hz
(3) Timer interrupt TI
CLKOUT = LOW

0
1
2
3
4
5
6
7

I2C stopAND&

CLKOUTVBACKUP (4)Power state

See INTERRUPT SCHEME.
Note that, when EIE = 1 and the flag EVF was cleared, the internal signal EI is generated when anExternal Event on EVI pin occurs and TSS = 0, or when an Automatic Backup Switchover occurs and
TSS = 1.
(2) Default value on delivery for CLKOE and CLKSY bits and for FD field (EEPROM 35h).
(3) For the timer interrupt signal TI, the CLKSY bit has no effect.
(4) When a frequency is selected and the RTC module is in VBACKUP Power state, CLKOUT pin is LOW.
When again in VDD Power state, CLKOUT pin outputs the frequency.
(1)

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4.5. SETTING AND READING THE TIME
Data flow and data dependencies starting from the 1 Hz clock tick:
1 Hz tick
SECONDSMINUTES

12_24 hour mode

HOURS

LEAP YEARCALCULATIONDATEWEEKDAY

MONTH

YEAR

During an I2C read/write access to any RTC register that takes less than 950 milliseconds, all time counters (clock
and calendar registers 00h to 06h) of the RV-3028-C7 are blocked. During this time the clock counter increment (1Hz tick) is inhibited to allow coherent data values. One counter increment (maximum one 1 Hz tick) occurring during
inhibition time is memorized and will be realized after the I2C STOP condition.
Exception: If during the inhibition time a 1 is written to the RESET bit or a value is written to the Seconds register an
eventual present memorized 1 Hz update is reset and the prescaler frequencies from 8192 Hz to 1 Hz are reset.
Resetting the prescaler will have an influence on the length of the current clock period on all subsequent peripherals(clock and calendar, CLKOUT, timer clock, update timer clock, UNIX clock, EVI input filter), (see also RESET BIT
FUNCTION).
When I2C read/write access has been terminated within 950 milliseconds (t < 950 ms), the time counters are
unblocked with the I2C STOP condition and a pending request to increment the time counters that occurred during
read or write access is correctly applied. Maximum one 1 Hz tick can be handled (see following Figure).
Access time for read/write operations:t < 950 ms
START

SLAVE ADDRESS

DATA

DATA

STOP

Because of this method, it is very important to make a read or write access in one go, that is, setting or reading
seconds through to years should be made in one single access. Failing to comply with this method could result in thetime becoming corrupted.
Hint: The UNIX Time counter does not know such register blocking (see UNIX TIME COUNTER).

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4.5.1.SETTING THE TIME
During an I2C read/write access to any RTC register with an access time of less than 950 ms, the time counters areblocked. After I2C STOP condition a possibly memorized 1 Hz tick is realized.
Advantage of register blocking: Prevents faulty writing to the clock and calendar registers during an I2C write access (no incrementing of timeregisters during the write access).
 After writing, one memorized 1 Hz tick is handled. Clock and calendar are updated.
 No reading is needed for control. The written data are coherent.
If the I2C write access takes longer than 950 ms the I2C bus interface is reset by the internal bus timeout function. In
this case the previous time counter values are maintained, the pending 1 Hz tick is realized and the clock counterincrement (1 Hz tick) continues to operate normally. Restarting of communications begins with transfer of the START
condition again.
The I2C auto increment Address Pointer is not reset by the I2C STOP condition nor by the internal stop forced after
timeout.
Two methods for setting the time can be distinguished:
1. Setting the time registers including Seconds register. Writing to the Seconds register resets an eventual
present memorized 1 Hz update and resets the prescaler frequencies from 8192 Hz to 1 Hz
(synchronization).
2. Setting the time registers without Seconds register. A possibly memorized 1 Hz tick during write access will
be realized. Old synchronicity persists.
Hint: Instead of writing to the Seconds register to synchronize the time counters the RESET BIT FUNCTION can beapplied. When writing 1 to the RESET bit, the value in the Seconds register does not change, but it also resets theprescaler frequencies from 8192 Hz to 1 Hz (synchronization).

4.5.2.READING THE TIME
During an I2C read/write access to any RTC register with an access time of less than 950 ms, the time counters areblocked. After I2C STOP condition a possibly memorized 1 Hz tick is realized.
Advantage of register blocking: Prevents faulty reading of the clock and calendar registers during an I 2C read access (no incrementing oftime registers during the read access).
 After reading, one memorized 1 Hz tick is handled. Clock and calendar are updated.
 No second reading is needed for control. The read data are coherent.
If the I2C read access takes longer than 950 ms the I2C bus interface is reset by the internal bus timeout function. In
this case all data that is read has a value of FFh, the pending 1 Hz tick is realized and the clock counter increment(1 Hz tick) continues to operate normally. Restarting of communications begins with transfer of the START condition
again.
The I2C auto increment Address Pointer is not reset by the I2C STOP condition nor by the internal stop forced after
timeout.

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4.6. EEPROM READ/WRITE
4.6.1.POR REFRESH (ALL CONFIGURATION EEPROM  RAM)
Automatic read of all Configuration EEPROM registers at Power On Reset (POR): At power up a refresh of the Configuration RAM mirror values by the values in the Configuration EEPROM
is automatically generated (see REGISTER RESET VALUES SUMMARY).
 The time of this first refreshment is tPREFR = ~66 ms.
 The EEbusy bit in the register Status (0Eh) can be used to monitor the status of the refreshment.
4.6.2.AUTOMATIC REFRESH (ALL CONFIGURATION EEPROM  RAM)
Read all Configuration EEPROM registers automatically:
 To keep the integrity of the configuration data, all data of the Configuration RAM are refreshed by the datain the Configuration EEPROM each 24 hours, at date increment (at the beginning of the last second before
midnight).
 The time of this automatic refreshment is tAREFR = ~3.5 ms.
 Refresh is only active when RV-3028-C7 is not in VBACKUP mode and not disabled by EERD (EEPROM
Memory Refresh Disable) bit.
 Hint: It is not always necessary/meaningful to turn off the auto-refresh (EERD = 1) before an EEPROM
access. e.g. if the current RTC time is 1 hour AM, etc.
4.6.3.UPDATE (ALL CONFIGURATION RAM  EEPROM)
Write to all Configuration EEPROM registers (see also USE OF THE CONFIGURATION REGISTERS): Before starting to change the configuration stored in the EEPROM, the auto refresh of the registers from the
EEPROM has to be disabled by writing 1 into the EERD control bit.
 Then the new configuration can be written into the configuration RAM registers, when the whole new
configuration is in the registers, writing the command 00h into the register EECMD, then the second
command 11h into the register EECMD will start the copy of the configuration into the EEPROM.
 The time of the update is tUPDATE = ~63 ms.
 When the transfer is finished (EEbusy = 0), the user can enable again the auto refresh of the registers by
writing 0 into the EERD bit in the Control 1 register.
4.6.4.REFRESH (ALL CONFIGURATION EEPROM  RAM)
Read all Configuration EEPROM registers: Before starting to read the configuration stored in the EEPROM, the auto refresh of the registers from the
EEPROM has to be disabled by writing 1 into the EERD control bit.
 Then the actual configuration can be read from the Configuration EEPROM registers, writing the command00h into the register EECMD, and then the second command 12h into the register EECMD will start the copyof the configuration into the RAM.
 The time of this controlled refreshment is tREFR = ~3.5 ms.
 Functions become active as soon as the RAM bytes are written.
 When the transfer is finished (EEbusy = 0), the user can enable again the auto refresh of the registers by
writing 0 into the EERD bit in the Control 1 register.

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4.6.5.WRITE TO ONE EEPROM BYTE (EEDATA (RAM)  EEPROM)
Write to one EEPROM byte of the Configuration EEPROM or User EEPROM registers: Before starting to change data stored in the EEPROM, the auto refresh of the registers from the EEPROM
has to be disabled by writing 1 into the EERD control bit.
 In order to write a single byte to the EEPROM, the address to which the data must be written is entered in
the EEADDR register and the data to be written is entered in the EEDATA register, then the command 00h
is written in the EECMD register, then a second command 21h is written in the EECMD register to start the
EEPROM write.
 The time to write to one EEPROM byte is tWRITE = ~16 ms.
 When the transfer is finished (EEbusy = 0), the user can enable again the auto refresh of the registers by
writing 0 into the EERD bit in the Control 1 register.
4.6.6.READ ONE EEPROM BYTE (EEPROM  EEDATA (RAM))
Read one EEPROM byte from Configuration EEPROM or User EEPROM registers: Before starting to read a byte in the EEPROM, the auto refresh of the registers from the EEPROM has to bedisabled by writing 1 into the EERD control bit.
 In order to read a single byte from the EEPROM, the address to be read is entered in the EEADDR register,then the command 00h is written in the EECMD register, then the second command 22h is written in the
EECMD register and the resulting byte can be read from the EEDATA register.
 The time to read one EEPROM byte is tREAD = ~1.4 ms.
 When the transfer is finished (EEbusy = 0), the user can enable again the auto refresh of the registers by
writing 0 into the EERD bit in the Control 1 register.

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4.6.7.EEBUSY BIT
The set EEbusy status bit (bit 7 in the Status register 0Eh) indicates that the EEPROM is currently handling a reador write request and will ignore any further commands until the current one is finished. At power up a refresh is
automatically generated. The time of this first refreshment is tPREFR = ~66 ms. After the refreshment is finished;
EEbusy is cleared to 0 automatically. The cleared EEbusy status bit indicates that the EEPROM transfer is finished.
To prevent access collision between the internal automatic EEPROM refresh cycle (EERD = 0) and external
EEPROM read/write access through interface the following procedures have to be applied.


Set EERD = 1
Automatic EEPROM Refresh needs to be disabled before EEPROM access.
Check for EEbusy = 0 Access EEPROM only if not busy.
Clear EERD = 0
It is recommended to enable Automatic EEPROM Refresh at the end of read/write
access.
 Write EEPROM
Wait 10 ms after each written EEPROM register before checking for EEbusy = 0 toallow internal data transfer (for Read EEPROM, wait 1 ms).
EEbusy bit flowcharts:
Read EEPROM or Refresh All (1)Write EEPROM or Update All (2)Disableautomatic refresh

Disableautomatic refresh

YES

EEPROMis busy?

EERD = 1

YES

EEbusy = 1?

NO
Read EEPROM
or Refresh All

Wait
1 ms

YES

EEPROMis busy?

EEPROM
Read/Refresh accessis permitted

Write EEPROM
or Update All

Wait 1 ms
to allow internal
EEPROM read

Wait until pervious
read cycle is finishedEEbusy = 1?

YES

EEPROM
Write/Update accessis permitted

Wait
10 ms

Wait 10 ms
to allow internal
EEPROM write

EEPROMis busy?

Wait until pervious
write cycle is finishedEEbusy = 1?

NO

YES

Next read?

NO
Enableautomatic refresh

EEbusy = 1?

NO

NO

YES

EEPROMis busy?

EERD = 1

Next write?

NO
Enableautomatic refresh

EERD = 0

EERD = 0(1) See READ ONE EEPROM BYTE (EEPROM  EEDATA (RAM))(2) See WRITE TO ONE EEPROM BYTE (EEDATA (RAM) 

and REFRESH (ALL CONFIGURATION EEPROM  RAM)

EEPROM) and UPDATE (ALL CONFIGURATION RAM  EEPROM)

Note: A minimum power supply voltage of VDD:WRITE = 1.5 V during the whole EEPROM write procedure is required;
i.e. until EEbusy = 0.

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4.6.8.EEPROM READ/WRITE CONDITIONS
During a read/write of the EEPROM, if the VDD supply drops, the device will continue to operate and communicate
until a switchover to VBACKUP occurs (in DSM or LSM mode). It is not recommended to operate during this time andall I2C communication should be halted as soon as VDD failure is detected.
During the time that data is being written to the EEPROM, VDD should remain above the minimum write voltage
VDD:WRITE = 1.5 V. If at any time VDD drops below this voltage, the data written to the device get corrupted.
To write to the EEPROM, the backup switchover circuit must switch back to the main power supply V DD. See also
AUTOMATIC BACKUP SWITCHOVER FUNCTION.

4.6.9.USE OF THE CONFIGURATION REGISTERS
The best practice method to use the Configuration EEPROM with RAM mirror registers at addresses 30h to 37h is
to make all Configuration settings in the RAM first and then to update all Configuration EEPROMs by the Update
EEPROM command.
Update all Configuration EEPROMs:
Configuration EEPROM
with RAM mirror

RAM mirror
EEPWE
EEPW 0EEPW 1EEPW 2EEPW 3
EEPROM Clkout
EEPROM Offset
EEPROM Backup

30

EEPROM
EEPWE
EEPW 0EEPW 1EEPW 2EEPW 3
EEPROM Clkout
EEPROM Offset
EEPROM Backup

30

37

37

The method, how to enable/disable write protection and how to change the reference password can be found insection USER PROGRAMMABLE PASSWORD (Configuration Registers 30h to 34h).
Configuration Registers 35h to 37h:
 EEPROM CLKOUT REGISTER, 35h – EEPROM Clkout
 EEPROM OFFSET REGISTER, 36h – EEPROM Offset
 EEPROM BACKUP REGISTER, 37h – EEPROM Backup
Edit the Configuration settings (example, when write protection is enabled (EEPWE = 255)):
1. Enter the correct password PW (PW = EEPW) to unlock write protection
2. Disable automatic refresh by setting EERD = 1
3. Edit Configuration settings in registers 35h to 37h (RAM)
4. Update EEPROM (all Configuration RAM  EEPROM) by setting EECMD = 00h followed by 11h
5. Enable automatic refresh by setting EERD = 0
6. Enter an incorrect password PW (PW ≠ EEPW) to lock the device

Note: RAM mirror of the Configuration registers defines the active zone. By writing only to the EEPROM, theconfigurations are not active. The configurations are activated as soon as a refresh occurs (POR refresh, Automaticrefresh or Refresh by software).
Note: To perform certain tests, it is sufficient to use only the RAM mirror. But the new, changed configurations arelost as soon as a refresh occurs (POR refresh, Automatic refresh or Refresh by software).

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4.7. INTERRUPT OUTPUT
The interrupt pin ̅̅̅̅̅
INT can be triggered by six different functions:







PERIODIC COUNTDOWN TIMER INTERRUPT FUNCTIONPERIODIC TIME UPDATE INTERRUPT FUNCTIONALARM INTERRUPT FUNCTION
EXTERNAL EVENT INTERRUPT FUNCTION
AUTOMATIC BACKUP SWITCHOVER INTERRUPT FUNCTION
POWER ON RESET INTERRUPT FUNCTION

4.7.1.SERVICING INTERRUPTS
̅̅̅̅̅ pin can indicate six types of interrupts. It outputs the logic OR operation result of these interrupt outputs.
The INT̅̅̅̅̅ pin produces a negative pulse or is at low level), the TF, UF, AF, EVF, BSF
When an interrupt is detected (when INT
and PORF flags can be read to determine which interrupt event has occurred.
̅̅̅̅̅ pin from changing to low level, clear the TIE, UIE, AIE, EIE and BSIE (EEPROM 37h) and PORIE
To keep INT̅̅̅̅̅ pin,
(EEPROM 35h) bits. To check whether an event has occurred without outputting any interrupts via the INT
software can read the TF, UF, AF, EVF, BSF and PORF interrupt flags (polling).
Caution: The EVF flag is also set by an event of the Backup Switchover function when bits TSS and TSE are set
to 1.

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4.7.2.INTERRUPT SCHEME
Interrupt Scheme (Part 1):
TRPT, TE, TD andRegisters 0Ah – 0Dh

to interface:read TF

TIMER FLAGTF
SET

COUNTDOWN COUNTER

TD

CLEAR

PULSE
GENERATOR 1
TRIGGER

TIE
tRTN1

0
1

CLEAR

(3) TI

from interface:clear TF

to interface:read UFUSELUPDATE FLAGUFSETUPDATE GENERATOR

USEL

PULSE
GENERATOR 2
TRIGGER

CLEAR

UIE
tRTN2

0
1

CLEAR

(3) UI

(2)

OR
1

INT

from interface:clear UF
AE_M

check now signal
MINUTE ALARM

to interface:read AF

1=

0

MINUTE TIME

AIE
AE_H

HOUR ALARM

1
=

ALARM
CONTROL(1)

ALARM FLAG
AF
SET

0

HOUR TIME

CLEAR

AE_WD
WEEKDAY ALARM

1=

from interface:clear AF01(3) AI
Part 20

WEEKDAYWADA

DATE ALARM
=
DATE

0
1

Only when all enabled alarm settings are matching.
It is only on increment to a matched case that the Alarm Flag AF is set.
(2) When bits TIE, UIE, AIE, EIE and BSIE (EEPROM 37h) and PORIE (EEPROM 35h) are disabled, pin̅̅̅̅̅
INT remains high impedance.
(3) See CLOCK OUTPUT SCHEME.
(1)

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Interrupt Scheme (Part 2):
to interface:read EVF
EIEPart 1
EHL, ETEVENT FLAG
EVF
SET

0
EVI

EXT. EVENT FUNCTION

1

SET

TSS

0

1

1
(4)

from interface:clear EVF
time stamp
scheme(4)

BSM, FEDEBACKUP FLAGBSF
SET

AUTOMATIC BACKUPSWITCHOVER FUNCTION

1

CLEAR

TSE

0

0

(3) EI
time stamp
schemeto interface:read BSF
BSIE

(2)

0
1

OR
1

INT

CLEAR

from interface:clear BSF

to interface:read PORF
PORIE

POR FLAG
PORF
SET

POWER ON RESET
POR

0

1

CLEAR

from interface:clear PORF

When bits TIE, UIE, AIE, EIE and BSIE (EEPROM 37h) and PORIE (EEPROM 35h) are disabled, pin ̅̅̅̅̅
INT
remains high impedance.
(3) See CLOCK OUTPUT SCHEME.
Note that, when EIE = 1 and the flag EVF was cleared, the internal signal EI is generated when anExternal Event on EVI pin occurs and TSS = 0, or when an Automatic Backup Switchover occurs and
TSS = 1.
(4) Caution: The EVF flag is also set by an event of the Backup Switchover function when bits TSS = 1 and(EIE = 1 or TSE = 1) are set.
(2)

See also Time Stamp scheme in section TIME STAMP FUNCTION.

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4.8. PERIODIC COUNTDOWN TIMER INTERRUPT FUNCTION
The Periodic Countdown Timer Interrupt function generates an interrupt event once (see SINGLE MODE (TRPT =0)) or periodically (see REPEAT MODE (TRPT = 1)) at any period set from 244.14 μs to 4095 minutes.
When starting the countdown timer for the first time, only the first period does not have a fixed duration. The amountof inaccuracy for the first timer period depends on the selected source clock (see FIRST PERIOD DURATION).
̅̅̅̅̅ pin goes to the low level and the TF flag is set to 1 to indicate that an
When an interrupt event is generated, the INT̅̅̅̅̅ pin is only effective if the TIE bit in the Control 2 register is set to 1. The
event has occurred. The output on the INT̅̅̅̅̅ pin (and on CLKOUT pin, when driven by TI signal) is automatically cleared after the
low-level output signal on INT
Auto reset time tRTN1 or it is cancelled when TF flag is cleared to 0.
 When TD = 00, tRTN1 = 122 µs
 When TD = 01, 10 or 11, tRTN1 = 7.813 ms
When bit TIE is set to 1, the internal countdown timer interrupt pulse (TI) can be used to enable the clock output on
CLKOUT pin automatically if CTIE and CLKIE bits are set to 1 and CLKOE bit is cleared to 0 and a frequency is
selected in the FD field. The interrupt pulses (TI) can even be used as CLKOUT frequency, when selecting 110 in
the FD field (see CLOCK OUTPUT SCHEME).

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4.8.1.PERIODIC COUNTDOWN TIMER DIAGRAM
Diagram of the Periodic Countdown Timer Interrupt function: Example with Repeat Mode (TRPT = 1), Interrupt on̅̅̅̅̅ pin (TIE = 1) and Countdown Timer Signal on CLKOUT pin (CLKOE = 1, FD = 110).
INT

TIE
TE
(TRPT, TD)

8

9

1

INT

4

5
t RTN1t RTN1t RTN1t RTN1t RTN1t RTN1t RTN1t RTN1

CLKOE = 1
FD = 110
CLKOUT

TF

3

event

2
1. period

6

period7

periodperiodperiodWrite operation

1

The Periodic Countdown Timer starts from the preset Timer Value in the Registers (0Ah, 0Bh) when writing 1
to the TE bit. In the same writing process TRPT can be set to 1 for Repeat Mode and the desired Timer
Clock Frequency can be selected in the TD field.
2
When the countdown value reaches 000h, an interrupt event occurs and, when TRPT is 1, the counter is
automatically reloaded with the preset Timer Value, and starts again the countdown.
3
When a Periodic Countdown Timer Interrupt occurs, the TF flag is set to 1.
4
If bits TIE and CLKOE are 1 and FD is set to 110 and a Periodic Countdown Timer Interrupt occurs, the ̅̅̅̅̅
INT
and CLKOUT output pins go LOW.
5̅̅̅̅̅ and CLKOUT output pins remains LOW during the Auto reset time tRTN1, and then they are
The INT
automatically cleared to 1. The TD field determines the Timer Clock Frequency and the Auto reset time tRTN1.
tRTN1 = 122 µs (TD = 00) or tRTN1 = 7.813 ms (TD = 01, 10, 11).
6
The TF flag retains 1 until it is cleared to 0 by software.
7̅̅̅̅̅ and CLKOUT pins are LOW, their status changes as soon as TF flag is cleared to 0.
If the INT
8̅̅̅̅̅ and CLKOUT pins are LOW, their status changes as soon as TIE bit is cleared to 0.
If the INT
9When a 0 is written to the TE bit, the Periodic Countdown Timer function is stopped and the ̅̅̅̅̅
INT and
CLKOUT pins are cleared after the Auto reset time tRTN1.

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4.8.2.USE OF THE PERIODIC COUNTDOWN TIMER INTERRUPTThe following registers, fields and bits are related to the Periodic Countdown Timer Interrupt and Automatic Clockoutput function:
 Timer Value 0 Register (0Ah) (see PERIODIC COUNTDOWN TIMER CONTROL REGISTERS) Timer Value 1 Register (0Bh) (see PERIODIC COUNTDOWN TIMER CONTROL REGISTERS) Timer Status 0 Register (0Ch) (see PERIODIC COUNTDOWN TIMER CONTROL REGISTERS) Timer Status 1 shadow Register (0Dh) (see PERIODIC COUNTDOWN TIMER CONTROL REGISTERS) TF flag (see STATUS AND CONTROL REGISTERS, 0Eh – Status)
 TRPT bit, TE bit and TD field (see STATUS AND CONTROL REGISTERS, 0Fh – Control 1)
 TIE bit (see STATUS AND CONTROL REGISTERS, 10h – Control 2)
 CTIE bit (see STATUS AND CONTROL REGISTERS, 12h – Clock Interrupt Mask)
For selecting Countdown Timer Signal for CLKOUT pin (CLKOE = 1 and FD = 110):
 CLKOE bit and FD field (see EEPROM CLKOUT REGISTER, 35h – EEPROM Clkout)
Prior to entering any timer settings for the Periodic Countdown Timer Interrupt, it is recommended to write a 0 to the̅̅̅̅̅ pin. When writing 1 to the RESET bit or writing a value to
TIE and TE bits to prevent inadvertent interrupts on INT
the Seconds register affects the length of a current countdown period (see RESET BIT FUNCTION). When the
Periodic Countdown Timer Interrupt function is not used, one Timer Value register (0Ah) can be used as RAM byte.
The Timer Clock Frequency selection field TD is used to set the countdown period (source clock) for the Periodic
Countdown Timer Interrupt function (four settings are possible).
Procedure to start the Periodic Countdown Timer Interrupt function and the Automatic Clock output function:
1.
2.
3.
4.
5.
6.
7.
8.

̅̅̅̅̅ pin.
Initialize bits TE, TIE and TF to 0. In that order, to prevent inadvertent interrupts on INT
Set TRPT bit to 1 if periodic countdown is needed (Repeat Mode).
Choose the Timer Clock Frequency and write the corresponding value in the TD field.
Choose the Countdown Period based on the Timer Clock Frequency, and write the corresponding Timer
Value to the registers Timer Value 0 (0Ah) and Timer Value 1 (0Bh). See following table.
Set the TIE bit to 1 if you want to get a hardware interrupt on ̅̅̅̅̅
INT pin.
Set CTIE bit to 1 to enable clock output when a timer interrupt occurs. See also CLOCK OUTPUTSCHEME.
Set the TIE and CLKOE bits to 1 and the FD field to 110 if you want to get the timer signal on CLKOUT.
Set the TE bit from 0 to 1 to start the Periodic Countdown Timer. The countdown starts at the rising edge of
the SCL signal after Bit 0 of the Address 0Fh is transferred. See subsequent Figure that shows the starttiming.

Countdown Period in seconds:
Countdown Period =Timer Value
Timer Clock Frequency

Countdown Period:
Timer Value(0Ah and 0Bh)

TD = 00 (4096 Hz)

0
1
2
:
41
205
410
2048
:
4095 (FFFh)

244.14 μs
488.28 μs:
10.010 ms
50.049 ms
100.10 ms
500.00 ms:
0.9998 s

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Countdown Period
TD = 01 (64 Hz)
TD = 10 (1 Hz)
15.625 ms
31.25 ms:
640.63 ms
3.203 s6.406 s32.000 s:
63.984 s

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1s
2s
:
41 s
205 s
410 s
2048 s:4095 sTD = 11 (1/60 Hz) )
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General countdown timer behavior:
Timer Value 0xx

03

Timer Value 1xx

00

Timer Status 0 (read only)xx

03

Timer Status 1 (read only)xx

00

Timer Clock
02

01

03

02

01

03

02

01

03

TE
TF
INT
periodWrite operation

periodThe first period has an uncertainty.
See table "First period duration for Timer Value n"

In this example, the Countdown Timer is in Repeat Mode (TRPT = 1) and it is assumed that the Timer Flag TF iscleared by software before the next countdown period expires.

Start timing of the Periodic Countdown Timer:
Address 0Fh

SCL

SDA

USEL

EERD

TE

TD1

TD0

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

ACK

Internal Timer

INT

event
1. period

Rising edge of the SCL signal

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4.8.3.FIRST PERIOD DURATION
When the TF flag is set, it indicates that an interrupt signal on ̅̅̅̅̅
INT is generated if this mode is enabled. See Section
INTERRUPT OUTPUT for details on how the interrupt can be controlled.
When starting the timer for the first time, the first period has an uncertainty. The uncertainty arises because of theactivation instruction of the interface clock, which is not synchronous to the Timer Clock Frequency. Subsequent
timer periods do not have such deviation. The amount of deviation for the first timer period depends on the chosen
Timer Clock Frequency, see following Table.
First period duration for Timer Value n(1):TD value

Timer Clock Frequency

00
01
10
11

4096 Hz64 Hz
1 Hz
1/60 HzFirst period duration
Minimum Period
Maximum Periodn × 244 µs
n × 15.625 ms
n×1s
n × 60 s(n + 1) × 244 µs(n +1) × 15.625 ms
n × 1 s + 15.625 ms
n × 60 s + 15.625 ms

Subsequent
periods durationn × 244 µs
n × 15.625 ms
n×1s
n × 60 s(1) Timer Values n from 1 to 4095 are valid. When the Timer Value is set to 0, the countdown timer does not start.

At the end of every countdown, the timer sets the Periodic Countdown Timer Flag (bit TF in Status Register). The TF
̅̅̅̅̅.
flag can only be cleared by command. When enabled, a pulse is generated at the interrupt pin INTWhen reading the Timer Value (Timer Value 0 and Timer Value 1), the preset value is returned and not the actual
value. The actual value of the Periodic Countdown Timer can be read in the registers Timer Status 0 and Timer
Status 1.

4.8.4.SINGLE MODE (TRPT = 0)
If TRPT bit is set to 0 (default), Single Mode is selected. In Single Mode the countdown timer will stop after reaching
0 and bit TE will be cleared automatically. The TF flag retains 1 until it is cleared to 0 by software.
Hint: An ongoing countdown can be stopped by writing 0 to the TE bit. No interrupt will be executed. The Timer Status
0 and Timer Status 1 registers store the last updated value.

4.8.5.REPEAT MODE (TRPT = 1)
If TRPT bit is set to 1, Repeat Mode is selected. In Repeat Mode the countdown timer is in the periodic countdown
mode where it will be automatically reloaded with the Timer Value from the Timer Value 0 and Timer Value 1 registers
when reaching 0. This will repeat until TE is cleared to 0. When a 0 is written to the TE bit, the Timer Status 0 andTimer Status 1 registers store the last updated value. The TF flag retains 1 until it is cleared to 0 by software.
Caution: Changing only TRPT from 1 to 0 during countdown to stop the function will automatically reload thecountdown timer with the preset Timer Value immediately because TE in the same register is still 1. The lastcountdown period will therefore be longer as intended but will stop correctly after reaching 0 and bit TE will be cleared
automatically.
Caution: A running countdown should not be stopped by writing 0 to the Timer Value because RV-3028-C7 outputs
64 Hz when the countdown value reaches 0.
Write as usual 0 to the TE bit to stop the function.

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4.9. PERIODIC TIME UPDATE INTERRUPT FUNCTION
The Periodic Time Update Interrupt function generates an interrupt event periodically at the One-Second or the OneMinute update time, according to the selected timer source with bit USEL.
When an interrupt event is generated, the ̅̅̅̅̅
INT pin goes to the low level and the UF flag is set to 1 to indicate that an
event has occurred. The output on ̅̅̅̅̅
INT pin is only effective if UIE bit in Control 2 register is set to 1. The low-level
output signal on the ̅̅̅̅̅
INT pin is automatically cleared after the Auto reset time t RTN2 or it is cancelled when UF flag iscleared to 0.
 When USEL = 0 (Second update), tRTN2 = 500 ms
 When USEL = 1 (Minute update), tRTN2 = 7.813 ms
When bit UIE is set to 1, the internal update interrupt pulse (UI) can be used to enable the clock output on CLKOUT
pin automatically, if CUIE and CLKIE bits are set to 1 and CLKOE bit is cleared to 0 and a frequency is selected in
the FD field (see CLOCK OUTPUT SCHEME).

4.9.1.PERIODIC TIME UPDATE DIAGRAM
Diagram of the Periodic Time Update Interrupt function:

UIE

INT

7

4

5

t RTN2

UF

2

event

1

3

periodt RTN2t RTN2t RTN2

6

periodperiodperiodWrite operation

1

A Periodic Time Update Interrupt event occurs when the internal clock value matches either the second or
the minute update time. The USEL bit determines whether it is the Second or the Minute period with thecorresponding Auto reset time tRTN2. tRTN2 = 500 ms (Second update) or tRTN2 = 7.813 ms (Minute update).
2
If UF flag was cleared beforehand and when a Periodic Time Update Interrupt occurs, the flag UF is set to 1.
3
The UF flag retains 1 until it is cleared to 0 by software.
4̅̅̅̅̅ pin output goes LOW.
If the UIE bit is 1 and a Periodic Time Update Interrupt occurs, the INT
5̅̅̅̅̅The INT pin output remains LOW during the Auto reset time tRTN2, and then it is automatically cleared to 1.
6
If the ̅̅̅̅̅
INT pin is LOW, its status changes as soon as UF flag is cleared to 0.
7̅̅̅̅̅ pin is LOW, its status changes as soon as UIE bit is cleared to 0.
If the INT

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4.9.2.USE OF THE PERIODIC TIME UPDATE INTERRUPTThe following bits are related to the Periodic Time Update Interrupt and Automatic Clock output function:
 UF flag (see STATUS AND CONTROL REGISTER, 0Eh – Status)
 USEL bit (see STATUS AND CONTROL REGISTER, 0Fh – Control 1)
 UIE bit (see STATUS AND CONTROL REGISTER, 10h – Control 2)
 CUIE bit (see STATUS AND CONTROL REGISTERS, 12h – Clock Interrupt Mask)
Prior to entering any other settings, it is recommended to write a 0 to the UIE bit to prevent inadvertent interrupts on̅̅̅̅̅ pin. The Periodic Time Update Interrupt function cannot be fully stopped, but by writing a 0 in the UIE bit, it
INT̅̅̅̅̅ pin.
prevents the occurrence of a hardware interrupt on the INTWhen writing 1 to the RESET bit or when writing to the Seconds register affects the length of a current update period(see RESET BIT FUNCTION).
Procedure to use the Periodic Time Update Interrupt and Automatic Clock output function:
1.
2.
3.
4.

Initialize bits UIE and UF to 0.
Choose the timer source clock and write the corresponding value in the USEL bit.
Set the UIE bit to 1 if you want to get a hardware interrupt on ̅̅̅̅̅
INT pin.
Set CUIE bit to 1 to enable clock output when a time update interrupt occurs. See also CLOCK OUTPUTSCHEME.
5. The first interrupt will occur after the next event, either second or minute change.

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4.10. ALARM INTERRUPT FUNCTION
The Alarm Interrupt function generates an interrupt for alarm settings such as weekday/date, hour and minutesettings.
When an interrupt event is generated, the ̅̅̅̅̅
INT pin goes to the low level and the AF flag is set to 1 to indicate that an
event has occurred. The output on the ̅̅̅̅̅
INT pin is only effective if the AIE bit in the Control 2 register is set to 1.
When bit AIE is set to 1, the internal alarm interrupt signal (AI) can be used to enable the clock output on CLKOUT
pin automatically, if CAIE and CLKIE bits are set to 1 and CLKOE bit is cleared to 0 and a frequency is selected in
the FD field (see CLOCK OUTPUT SCHEME).

4.10.1. ALARM DIAGRAM
Diagram of the Alarm Interrupt function:

AIE
5

INT

4

AF

2

event

1

3

6

alarm

7

alarm

Write operation

1

A weekday/date, hour or minute alarm interrupt event occurs when all selected Alarm registers (AE_x bits)
match to the respective counters. The WADA bit determines whether it is the weekday or date.

2

When an Alarm Interrupt event occurs, the AF flag is set to 1.

3

The AF flag retains 1 until it is cleared to 0 by software.
If the AIE bit is 1 and an Alarm Interrupt occurs, the ̅̅̅̅̅
INT pin output goes LOW.

45

If the AIE value is changed from 1 to 0 while the ̅̅̅̅̅
INT pin output is LOW, the ̅̅̅̅̅
INT pin immediately̅̅̅̅̅ status can be controlled by the AIE bit.
changes its status. While the AF flag is 1, the INT
6̅̅̅̅̅ pin is LOW, its status changes as soon as the AF flag is cleared from 1 to 0.
If the INT
7̅̅̅̅̅ pin status does not go LOW.
If the AIE bit value is 0 when an Alarm Interrupt occurs, the INT

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4.10.2. USE OF THE ALARM INTERRUPTThe following registers and bits are related to the Alarm Interrupt and Automatic Clock output function:
 Minutes Register (01h) (see CLOCK REGISTERS) Hours Register (02h) (see CLOCK REGISTERS) Weekday Register (03h) (see CALENDAR REGISTERS) Date Register (04h) (see CALENDAR REGISTERS) Minutes Alarm Register and AE_M bit (07h) (see ALARM REGISTERS) Hours Alarm Register and AE_H bit (08h) (see ALARM REGISTERS) Weekday/Date Alarm Register and AE_WD bit (09h) (see ALARM REGISTERS) AF flag (see STATUS AND CONTROL REGISTER, 0Eh – Status)
 WADA bit (see STATUS AND CONTROL REGISTERS, 0Fh – Control 1)
 AIE and 12_24 bits (see STATUS AND CONTROL REGISTERS, 10h – Control 2)
 CAIE bit (see STATUS AND CONTROL REGISTERS, 12h – Clock Interrupt Mask)
Prior to entering any timer settings for the Alarm Interrupt, it is recommended to write a 0 to the AIE bit to prevent
inadvertent interrupts on ̅̅̅̅̅
INT pin. When writing 1 to the RESET bit or writing a value to the Seconds register affects
the time to the next alarm interrupt (see RESET BIT FUNCTION). When the Alarm Interrupt function is not used, one
Byte (07h) of the Alarm registers can be used as RAM byte. In such case, be sure to write a 0 to the AIE bit (if theAIE bit value is 1 and the Alarm register is used as RAM register, ̅̅̅̅̅
INT may change to low level unintentionally).
Procedure to use the Alarm Interrupt and Automatic Clock output function:
1. Initialize bits AIE and AF to 0.
2. Choose weekday alarm or date alarm (weekday/date) by setting the WADA bit. WADA = 0 for weekday alarm
or WADA = 1 for date alarm.
3. Write the desired alarm settings in registers 07h to 09h. The three alarm enable bits, AE_M, AE_H and
AE_WD, are used to select the corresponding register that has to be taken into account for match or not.
See the following table.
4. Set CAIE bit to 1 to enable clock output when an alarm occurs. See also CLOCK OUTPUT SCHEME.
̅̅̅̅̅ pin.
5. Set the AIE bit to 1 if you want to get a hardware interrupt on INT
Alarm Interrupt:
AE_WD

Alarm enable bits
AE_H

Alarm event

AE_M

0
0
0
When minutes, hours and weekday/date match (once per weekday/date)001When hours and weekday/date match (once per weekday/date)0
10When minutes and weekday/date match (once per hour per weekday/date)0
1
1
When weekday/date match (once per weekday/date)100When hours and minutes match (once per day)1
0
1
When hours match (once per day)1
1
0
When minutes match (once per hour)11
1
All disabled – Default value
AE_x bits (where x is WD, H or M)
AE_x = 0: Alarm is enabled
AE_x = 1: Alarm is disabled – Default value

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4.11. EXTERNAL EVENT INTERRUPT FUNCTION
The External Event Interrupt and the Time Stamp function are enabled by the control bits TSS, TSE and EIE. With
the ET field the EVI input events can be configured either for edge detection, or for level detection with filtering, andwith the EHL bit the active edge or level can be configured.
If enabled (TSS = 0, TSE = 1, EIE =1 and EVF flag was cleared to 0 before) and an External Event on EVI pin is̅̅̅̅̅ is issued
detected, the clock and calendar registers are captured and copied into the Time Stamp registers, the INT
and the EVF flag is set to 1 to indicate that an external event has occurred.
When bit TSS = 0 and bit EIE = 1, the internal event interrupt signal (EI) can be used to enable the clock output on
CLKOUT pin automatically, if CEIE and CLKIE bits are set to 1 and CLKOE bit is cleared to 0 and a frequency is
selected in the FD field (see CLOCK OUTPUT SCHEME).
Caution: The EVF flag is also set by an event of the Backup Switchover function when bits TSS and TSE are set
to 1.

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4.11.1. EXTERNAL EVENT DIAGRAM
Diagram of the External Event Interrupt function. Example with EHL = 1 for high level / rising edge detection:

TSE

7

1

8

TSR

10

EIE

9

INT
tD EL AY

EVF

3

EVI

2

5

event

event

4

6

event

event

Clock & Calendar
registers

Set value to A

Count TS register

00h if reseted

01h

02h

03h

00h

TS registers(TSOW = 1)00h if reseted

A+1

A+2

A+3

All 00h

TS registers(TSOW = 0, default)

00h if reseted

A+1

A+2

A+3

A+1

A+4

A+5

All 00h

Write operation

1

Initialize clock and calendar and set bits TSS = 0 and TSE = 1 if a Time Stamp from the External Event
Interrupt function is needed and select TSOW (0 or 1). Set EIE bit to 1 if interrupt on ̅̅̅̅̅
INT pin is required. The
EVF flag needs to be cleared to reset the ̅̅̅̅̅
INT pin and to prepare the system for an event. In this example,
EHL = 1 for high level / rising edge detection. Select edge detection (ET = 00) or level detection with filtering(ET ≠ 00).

2

An External Event on EVI pin is detected. Pay attention to the debounce time when using filtering (ET ≠ 00).
The value (A+1) is captured/copied into the TS registers and the value in the Count TS register isincremented by one. The counter Count TS is always working, regardless of the value of the overwrite bit
TSOW.
3̅̅̅̅̅ pin output goes LOW when EIE = 1.
When an External Event Interrupt occurs, EVF flag is set to 1 and INT
4The EVF flag retains 1 until it is cleared to 0 by software.
No interrupt occurs on ̅̅̅̅̅
INT pin because the EVF flag was not set back to 0. But, new value (A+2) is captured
in the TS registers if the Time Stamp overwrite bit TSOW is set to 1.
6
When edge detection is enabled (ET = 00) the EVF flag can be cleared, even if EVI input is high level.
When level detection with filtering is enabled (ET ≠ 00) the EVF flag will be set again after tDELAY(tSP < tDELAY < 2 tSP). When EVI input is low level, EVF can also be cleared.
7
If TSE is set to 0, no time stamp is captured.
8
If the EVI input is high level and the TSE bit is set from 0 to 1, no event is detected.
9̅̅̅̅̅ status can be controlled by the EIE bit.
While the EVF flag is 1, the INT
5

10When writing 1 to TSR bit, all seven time stamp registers (Count TS to Year TS) are reset to 00h. Bit TSR
always returns 0 when read.

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4.11.2. USE OF THE EXTERNAL EVENT INTERRUPTThe following registers and bits are related to the External Event Interrupt, Time Stamp and Automatic Clock output
function:


















Seconds Register (00h) (see CLOCK REGISTERS)Minutes Register (01h) (see CLOCK REGISTERS)
Hours Register (02h) (see CLOCK REGISTERS)
Date Register (04h) (see CALENDAR REGISTERS)Month Register (05h) (see CALENDAR REGISTERS)
Year Register (06h ) (see CALENDAR REGISTERS)Count TS Register (14h) (see TIME STAMP REGISTERS)
Seconds TS (15h) (see TIME STAMP REGISTERS)Minutes TS (16h) (see TIME STAMP REGISTERS)
Hours TS (17h) (see TIME STAMP REGISTERS)
Date TS (18h) (see TIME STAMP REGISTERS)Month TS (19h) (see TIME STAMP REGISTERS)
Year TS (1A) (see TIME STAMP REGISTERS)EVF flag (see STATUS AND CONTROL REGISTERS, 0Eh – Status)
TSE, EIE and 12_24 bits (see STATUS AND CONTROL REGISTERS, 10h – Control 2)
CEIE bit (see STATUS AND CONTROL REGISTERS, 12h – Clock Interrupt Mask)
EHL bit, ET field, TSR bit, TSOW bit and TSS bit (see EVENT CONTROL REGISTER, 13h – Event Control)

Prior to entering any timer settings for the event interrupt, it is recommended to write a 0 to the TSE and EIE bit toprevent inadvertent interrupts on ̅̅̅̅̅
INT pin.
Note that changing TSS bit value from 1 to 0 before clearing TSE and EIE can create unwanted interrupts (according
to EHL bit, but regardless of the status of the ET field).
Procedure to use the External Event Interrupt, Time Stamp and Automatic Clock output function:
1.
2.
3.
4.
5.
6.

Initialize bits TSE and EIE to 0.
Clear flag EVF to 0.
Set TSS bit to 0 to select External Event on EVI pin as Time Stamp and Interrupt source.
Set EHL bit to 1 or 0 to choose high or low level (or rising or falling edge) detection on pin EVI.
Select EDGE DETECTION (ET = 00) or LEVEL DETECTION WITH FILTERING (ET ≠ 00).
Set TSOW bit to 1 if the last occurred event has to be recorded and TS registers are overwritten.
Hint: The counter Count TS is always working, independent of the settings of the overwrite bit TSOW.
7. Write 1 to TSR bit, to reset all Time Stamp registers to 00h. Bit TSR always returns 0 when read.
8. Set CEIE bit to 1 to enable clock output when external event occurs. See also CLOCK OUTPUT SCHEME.
9. Set TSE bit to 1 if you want to enable the Time Stamp function.
10. Set EIE bit to 1 if you want to get a hardware interrupt on ̅̅̅̅̅
INT pin.

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4.11.3. EDGE DETECTION (ET = 00)
Example with rising edge detection and interrupt output:

EVI

EVF

1

2

INT
Write operation

Settings: EHL = 1, ET = 00, TSS = 0, EIE = 1.
̅̅̅̅̅ output pin goes LOW.
When a rising edge on EVI pin is detected, the EVF flag is set to 1 and the INT
2̅̅̅̅̅ pin is LOW, its status changes as soon as the EVF flag is cleared to 0, even if EVI input is highIf the INTlevel.
1

4.11.4. LEVEL DETECTION WITH FILTERING (ET ≠ 00)
Example with high level detection and interrupt output:

EVI

sampling

1

1
tSP

1
tSP

4

2
tSP

EVF

tSP

tSP

3

INT
tSP < tD EL AY < 2 tSP

tSP < tD EL AY < 2 tSP

Write operation

Settings: EHL = 1, ET ≠ 00, TSS = 0, EIE = 1.
Available sampling periods for the digital debounce filtering:ET = 01, tSP = 3.9 ms
ET = 10, tSP = 15.6 ms
ET = 11, tSP = 125.0 ms
1From the previous sampling pulse to this sampling pulse, no stable high level was detected.
2
̅̅̅̅̅
If a stable high level on EVI pin during one sampling period is detected, the EVF flag is set to 1 and the INT
output pin goes LOW. The delay time tDELAY is between tSP and 2 tSP.
3
If the ̅̅̅̅̅
INT pin is LOW, its status changes as soon as the EVF flag is cleared to 0.
4
When the high level on EVI pin remains stable, again, the EVF flag is set to 1 and the ̅̅̅̅̅
INT output pin goes
LOW. The delay time tDELAY is again between tSP and 2 tSP.

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4.12. AUTOMATIC BACKUP SWITCHOVER INTERRUPT FUNCTION
The Automatic Backup Switchover Interrupt function generates an interrupt event when the BSM field (EEPROM
37h) is set to 01 (DSM) or 11 (LSM) and a switchover from VDD Power state to VBACKUP Power state occurs.
If enabled (TSS = 1, TSE = 1, BSIE = 1 and BSF flag was cleared to 0 before) and a Backup Switchover is detected,̅̅̅̅̅ is issued and thethe clock and calendar registers are captured and copied into the Time Stamp registers, the INT
BSF flag is set to 1 to indicate that a Backup Switchover has occurred.
Similar to the External Event Interrupt Function, clock output on CLKOUT pin can be controlled by the Automatic
Backup Switchover Interrupt function. When bits TSS and EIE are set to 1, the internal event interrupt signal (EI)
created by the Automatic Backup Switchover function can be used to enable the clock output on CLKOUT pin
automatically.
If enabled (TSS, EIE, CEIE, CLKIE are set to 1 and CLKOE is cleared to 0 and a frequency is selected in the FD
field), when again in VDD Power state, CLKOUT pin outputs the frequency (see INTERRUPT SCHEME and CLOCKOUTPUT SCHEME).
Note that a debounce logic provides a debounce time tDEB of 122 μs to 183 μs, which will filter VDD oscillation when
the backup switchover will switch back from VBACKUP to VDD (see AUTOMATIC BACKUP SWITCHOVER FUNCTION).
I2C access is possible in VDD Power state after the debounce time tDEB.
Note that the FEDE bit (EEPROM 37h) should always be set to 1, so that Fast Edge Detection (≥ 7 V/ms) is enabled(see EEPROM BACKUP REGISTER). FEDE = 1 is the default value on delivery.

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4.12.1. AUTOMATIC BACKUP SWITCHOVER DIAGRAM
Diagram of the Automatic Backup Switchover Interrupt function:

TSE

7

1

8

TSR

10

BSIE

9

INT

BSF

3

VBACKUPPower state

2

5

event

event

4

6

event

event

Clock & Calendar
registers

Set value to A

Count TS register

00h if reseted

01h

02h

03h

00h

TS registers(TSOW = 1)00h if reseted

A+1

A+2

A+3

All 00h

TS registers(TSOW = 0, default)

00h if reseted

A+1

A+2

A+3

A+1

A+4

A+5

All 00h

Write operation (I2C access only in VDD Power state)1

Initialize clock and calendar and set bits TSS and TSE to 1 and select TSOW (0 or 1) if a Time Stamp from̅̅̅̅̅ pin is required. The BSF
the Backup Switchover function is needed and set BSIE bit to 1 if interrupt on INT̅̅̅̅̅flag needs to be cleared to reset the INT pin and to prepare the system for an event. To enable switchover
function the BSM field (EEPROM 37h) is set to 01 (DSM) or 11 (LSM).

2

A backup switchover from VDD Power state to VBACKUP Power state occurs. The value (A+1) is
captured/copied into the TS registers and the value in the Count TS register is incremented by one.
The counter Count TS is always working, regardless of the settings of the overwrite bit TSOW.
3
When an Automatic Backup Switchover Interrupt event occurs, the BSF flag is set to 1and ̅̅̅̅̅
INT pin output
goes LOW when BSIE = 1.
4

The BSF flag retains 1 until it is cleared to 0 by software.
No interrupt occurs on ̅̅̅̅̅
INT pin because the BSF flag was not set back to 0. But, new value (A+2) is captured
in the TS registers if the Time Stamp overwrite bit TSOW is set to 1.
6
When the ̅̅̅̅̅
INT pin is LOW, its status changes as soon as the BSF flag is cleared to 0.
5

7

If TSE is set to 0, no time stamp is captured.

8

If BSF is 1 and the TSE bit is set from 0 to 1, no event is detected.
While the BSF flag is 1, the ̅̅̅̅̅
INT status can be controlled by the BSIE bit.

9
10

When writing 1 to TSR bit, all seven time stamp registers (Count TS to Year TS) are reset to 00h. Bit TSR
always returns 0 when read.

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4.12.2. USE OF THE AUTOMATIC BACKUP SWITCHOVER INTERRUPTThe following registers and bits are related to the Automatic Backup Switchover Interrupt, Time Stamp and Automatic
Clock output function:



















Seconds Register (00h) (see CLOCK REGISTERS)Minutes Register (01h) (see CLOCK REGISTERS)
Hours Register (02h) (see CLOCK REGISTERS)
Date Register (04h) (see CALENDAR REGISTERS)Month Register (05h) (see CALENDAR REGISTERS)
Year Register (06h ) (see CALENDAR REGISTERS)Count TS (14h) (see TIME STAMP REGISTERS)
Seconds TS (15h) (see TIME STAMP REGISTERS)Minutes TS (16h) (see TIME STAMP REGISTERS)
Hours TS (17h) (see TIME STAMP REGISTERS)
Date TS (18h) (see TIME STAMP REGISTERS)Month TS (19h) (see TIME STAMP REGISTERS)
Year TS (1A) (see TIME STAMP REGISTERS)BSF flag (see STATUS AND CONTROL REGISTERS, 0Eh – Status)
TSE, EIE and 12_24 bits (see STATUS AND CONTROL REGISTERS, 10h – Control 2)
CEIE bit (see STATUS AND CONTROL REGISTERS, 12h – Clock Interrupt Mask)
TSR bit, TSOW bit and TSS bit (see EVENT CONTROL REGISTER, 13h – Event Control)
BSIE bit, FEDE bit and BSM field (see EEPROM BACKUP REGISTER, 37h – EEPROM Backup)

Prior to entering any other settings, it is recommended to write a 0 to the TSE and BSIE bit to prevent inadvertentinterrupts on ̅̅̅̅̅
INT pin.
Procedure to use the Automatic Backup Switchover Interrupt, Time Stamp and Automatic Clock output function:
1.
2.
3.
4.

Initialize bits TSE and BSIE to 0.
Clear flag BSF to 0.
Set TSS bit to 1 to select Backup Switchover as Time Stamp and Interrupt source.
Set TSOW bit to 1 if the last occurred event has to be recorded and TS registers are overwritten.
Hint: The counter Count TS is always working, independent of the settings of the overwrite bit TSOW.
5. Write 1 to TSR bit, to reset all Time Stamp registers to 00h. Bit TSR always returns 0 when read.
6. Set CEIE bit to 1 to enable clock output when a backup switchover occurs.
Caution: This function is only working with the Automatic Backup Switchover function when bits TSS and
TSE are set to 1. See also CLOCK OUTPUT SCHEME.
7. Set TSE bit to 1 if you want to enable the Time Stamp function.
8. The FEDE bit should always be set to 1, so that Fast Edge Detection (≥ 7 V/ms) is enabled.
9. Set the BSIE bit to 1 if you want to get a hardware interrupt on ̅̅̅̅̅
INT pin.
10. Choose the switchover mode (DSM or LSM) and write the corresponding value in the BSM field.
See also EEPROM READ/WRITE CONDITIONS.

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4.13. POWER ON RESET INTERRUPT FUNCTION
The Power On Reset Interrupt function is enabled by the PORIE bit (EEPROM 35h). The PORIE bit has to be set
beforehand in the EEPROM, not in the RAM (see EEPROM READ/WRITE).
When voltage drop below VPOR is detected (VDD < VPOR) the PORF flag is set to 1 to indicate that a Power On Reset̅̅̅̅̅ pin goes to low level.
has occurred and when the PORIE bit is 1 the INTA PORF value of 1 indicates also that the time information is corrupted. The value 1 is retained until a 0 is written by
the user.

4.13.1. POWER ON RESET DIAGRAM
Diagram of the Power On Reset Interrupt function:

PORIE

2

7
5

INT

PORF

VDD

3

1

8

4

6

VPOR

VPOR
tREFR
tSTART

State

POR

tREFR
tDELAYtSTART
Operating

POR

tDELAY
OperatingWrite operation

1

Flag PORF is set when VDD was below VPOR.
If the PORIE bit (EEPROM 35h) was set to 1 beforehand (in EEPROM), the PORIE bit in the RAM is set to 1
after the start-up time tSTART = 0.2 s including the first refreshment time tPREFR = ~66 ms.
3̅̅̅̅̅ pin output goes LOW after a delay time of
If the PORIE bit is 1 and a Power On Reset event occurs, the INTtDELAY = ~1 ms.
4
The PORF flag retains 1 until it is cleared to 0 by software.
5̅̅̅̅̅ status can be controlled by the PORIE bit.
While the PORF flag is 1, the INT
6̅̅̅̅̅ pin is LOW, its status changes as soon as the PORF flag is cleared to 0.
If the INT
7
If the PORIE bit (EEPROM 35h) was set to 1 beforehand (in EEPROM), the PORIE bit in the RAM is set to 1
after the start-up time tSTART = 0.2 s including the first refreshment time tPREFR = ~66 ms.
Or else, if the PORIE bit (EEPROM 35h) was set to 0 beforehand (in EEPROM), the PORIE bit in the RAM is
set to 0 after the start-up time tSTART = 0.2 s and the first refreshment time tPREFR = ~66 ms.
8̅̅̅̅̅ pin output goes LOW after a delay time
If the PORIE bit is 1 when a Power On Reset event occurs, the INT
of tDELAY = ~1 ms.
̅̅̅̅̅ pin output stays inactive (HIGH).
Or else, if the PORIE bit is 0 when a Power On Reset event occurs, the INT
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4.13.2. USE OF THE POWER ON RESET INTERRUPTThe following registers and bits are related to the Power On Reset Interrupt function (including EEPROM handling):







PORF flag and EEbusy bit (see STATUS AND CONTROL REGISTERS, 0Eh – Status)
EERD bit (see STATUS AND CONTROL REGISTERS, 0Fh – Control 1)
EE Address register (25h) (see EEPROM MEMORY CONTROL REGISTERS)
EE Data register (26h) (see EEPROM MEMORY CONTROL REGISTERS)EE Command register (27h) (see EEPROM MEMORY CONTROL REGISTERS)PORIE bit (see EEPROM CLKOUT REGISTER, 35h – EEPROM Clkout)

The PORIE bit has to be set beforehand in the EEPROM, not in the RAM (see EEPROM READ/WRITE).
Procedure to use the Power On Reset Interrupt function:
1. In the EEPROM, set the PORIE bit to 1 if you want to get a hardware interrupt on ̅̅̅̅̅
INT pin at the next PowerOn Reset event. Procedure according to EEPROM READ/WRITE.
2. The first interrupt will occur after the next POR event.

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4.14. TIME STAMP FUNCTION
The Time Stamp function is enabled by the control bit TSE. Sources are the External Event Interrupt function(TSS = 0) or the Automatic Backup Switchover Interrupt function (TSS = 1).
If a source is enabled and an event is detected, the Time Stamp (TS) registers are recorded. When the TSOW bit is
set to 0 and the EVF flag was cleared to 0 before, only one (the first) event is recorded. When the TSOW bit is set to1, the last event is recorded (EVF flag does not need to be cleared). The counter Count TS is always working,independent of the settings of the overwrite bit TSOW.


When writing 1 to TSR bit, all seven time stamp registers (Count TS to Year TS) are reset to 00h. Bit TSR
always returns 0 when read.
Before starting the Time Stamp function, it is recommended to write 0 to the TSE bit and 1 to TSR bit.
When writing 1 to the RESET bit or when writing to the Seconds register, Time Stamp capture/copy does
not occur. Bit RESET always returns 0 when read.
Note that changing TSS bit value from 1 to 0 before clearing TSE can create unwanted Time Stampcapture/copy from the External Event Interrupt function (according to EHL bit, but regardless of the statusof the ET field).

Procedure for using the Time Stamp function:
1. Initialize bits TSE and EIE to 0.
2. Select TSOW (0 or 1), clear EVF and BSF.
3. Write 1 to TSR bit, to reset all Time Stamp registers to 00h. Bit TSR always returns 0 when read.
4. Select the External Event Interrupt function (TSS = 0) or the Automatic Backup Switchover Interrupt
function (TSS = 1) as time stamp source and initialize the appropriate function (see EXTERNAL EVENT
INTERRUPT FUNCTION or AUTOMATIC BACKUP SWITCHOVER INTERRUPT FUNCTION).
5. Set the TSE bit to 1 to enable the Time Stamp function.
̅̅̅̅̅ signal is issued when EIE (RAM) or BSIE (EEPROM 37h) bit is set to 1. The EVF or BSF flag is set toHint: The INT
1 to indicate that a corresponding event has occurred.
Caution: Because the EVF flag is internally used for the identification of a First Event detection it is set by an eventfrom the External Event Interrupt function (TSS = 0, TSE = 1) or by an event of the Backup Switchover Interrupt
function (TSS = 1, TSE = 1). See also the following scheme:

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Time Stamp scheme:
RESET

Seconds (4)PRESCALER

EHL, ETInterrupt
scheme

EXT. EVENT FUNCTION

EVI

TSS

BSM, FEDETSOW (1)0 first event

(1)

(2)

(3)
(4)
(5)

EVF

1

auto
Seconds
Minutes
Hours
Date
Month
Year

Interrupt
scheme

0

0

0

1

1

1

1

capture/copy
auto

(3)

TSR

0 autoInterrupt
scheme1 Hz tick0

TSE

Interrupt
schemeAUTOMATIC BACKUPSWITCHOVER FUNCTION

1

1 Hz

reset

clear

1

(2)
AND
&

OR
1

interface:read/write

Time Stamp

Count TS
Seconds TS
Minutes TS
Hours TS
Date TSMonth TSYear TS

interface: (5)read only

enable overwrite

1 last event

When TSOW bit is set to 1 the TS registers (Seconds TS to Year TS) are overwritten. The last occurred
event is recorded. When TSOW bit is set to 0, the TS registers are overwritten once only. To initialize or
reinitialize the first event function, the EVF has to be cleared (the TS registers can be cleared by writing
1 to the TSR bit). The counter Count TS is always working, independent of the settings of the overwrite
bit TSOW.
If set to 0 beforehand, the EVF flag indicates the occurrence of an External Event or a Backup
Switchover. The value 1 is retained until a 0 is written by the user.
The EVF flag is set to 1 when: An external event occurs and TSS = 0 and (EIE = 1 or TSE = 1).
 A backup switchover occurs and TSS = 1 and (EIE = 1 or TSE = 1).
When writing 1 to TSR bit, all seven time stamp registers (Count TS to Year TS) are reset to 00h. Bit
TSR always returns 0 when read.
Writing 1 to the RESET bit or writing to the Seconds register does not create an extra 1 Hz tick and theTime Stamp capture/copy does not occur. Bit RESET always returns 0 when read.
During I2C read access to the TS registers the time stamp capture function is blocked.

See also Interrupt Scheme (Part 2) in section INTERRUPT SCHEME.

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4.15. FREQUENCY OFFSET CORRECTION
An aging adjustment or accuracy tuning can be done with the EEOffset value. The correction is made purely digitaland has only the effect of shifting the time vs. temperature curve vertically up or down. It has no effect on the timevs. temperature characteristics of the final frequency. The EEOffset value contains a two's complement number witha range of +255 to -256 adjustment steps. The minimal correction step (one LSB) is ±1 / (16384 × 64) = ±0.9537 ppm
and the maximum correction range is from +243.2 ppm to -244.1 ppm. The compensation period is 64 seconds.
Note that the signed offset value EEOffset corresponds to the correction value of the measured frequency (32.768
kHz). The non-volatile user programmable EEOffset value (factory calibrated time accuracy is ±1 ppm @ 25°C) canbe adjusted by the user. See chapters below.
Caution: Bits 8 to 1 of the EEOffset value are in the register 36h – EEPROM Offset (see EEPROM OFFSETREGISTER). Bit 0 (LSB) of the EEOffset value is in the register 37h – EEPROM Backup (see EEPROM BACKUPREGISTER).

4.15.1. EEOFFSET VALUE DETERMINATIONThe EEOffset value is determined by the following process:1. Select the 32.768 kHz frequency on the CLKOUT pin.
(If another frequency than 32.768 kHz is selected, the EEOffset value has to be set to 0 so that theuncorrected frequency can be measured, and the following calculations have to be adapted.)
2. Measure the frequency Fmeas at CLKOUT pin in Hz.
3. Compute the offset value required in ppm: POffset = ((Fmeas – 32768) / 32768 × 1’000’000)
4. Compute the offset value in steps: Offset = POffset / (1 / (16384 × 64) in ppm) = POffset / (0.9537 ppm)
5. If Offset > 256, the frequency is too high to be corrected.
6. Else if 1 ≤ Offset ≤ 256 (correction is -1 ≥ OffsetCorr. ≥ -256),  set EEOffset = 512 – Offset
7. Else if -255 ≤ Offset ≤ 0 (correction is +255 ≤ OffsetCorr. ≤ 0),  set EEOffset = - Offset
8. Else the frequency is too low to be corrected.
Examples: If 32768.48 Hz is measured when the 32.768 kHz clock is selected, the offset is +0.48 Hz, which is+0.48 Hz / 32768 Hz × 1’000’000 = +14.648 ppm. The Offset value in steps is then calculated as follows:+14.648 ppm / 0.9537 ppm = +15.36, the rounded integral part is 15 (the offset correction is -15 steps).
The unsigned EEOffset value is then: 512 – 15 = +497. In binary, EEOffset = 111110001.


If 32767.52 Hz is measured when the 32.768 kHz clock is selected, the offset is -0.48 Hz, which is-0.48 Hz / 32768 Hz × 1’000’000 = -14.648 ppm. The Offset value in steps is then calculated as follows:-14.648 ppm / 0.9537 ppm = -15.36, the rounded integral part is -15 (the offset correction is +15 steps).
The EEOffset value is then: - (-15) = +15. In binary, EEOffset = 000001111.

4.15.2. VERIFICATION OF THE CORRECTED TIME ACCURACY
The offset correction can be verified by the following process:1. Enter the calculated EEOffset value (see EEOFFSET VALUE DETERMINATION).
2. Select the 1 Hz frequency on the CLKOUT pin (if another frequency is selected the following calculations
have to be adapted).
3. Measure every period during one compensation period of 64 seconds at CLKOUT pin.
4. Calculate the average frequency Fmeas_aver in Hz.
5. Compute the new achieved offset value in ppm: POffset = ((Fmeas_aver – 1) / 1 × 1’000’000)

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4.16. UNIX TIME COUNTERThe UNIX Time counter is a 32-bit counter, unsigned integer, which rolls over to 00000000h when reaching the value
FFFFFFFFh. The 4 bytes are fully readable and writable. The counter source clock is the digitally offset compensated
1 Hz tick.

4.16.1. SETTING THE UNIX TIME
During I2C write access with an access time smaller than 950 ms the UNIX registers (UNIX Time 0 to UNIX Time 3)
are blocked. Unlike to the setting of the clock and calendar registers, after I2C STOP condition a possibly memorized
1 Hz tick can be lost.
Advantage of register blocking: Prevents faulty writing to the UNIX registers during an I 2C write access (no incrementing of UNIX registers
during the write access).
 No reading is needed for control. The written data are coherent.
If the I2C write access takes longer than 950 ms the I2C bus interface is reset by the internal bus timeout function. In
this case the previous UNIX value is maintained and the UNIX increment (1 Hz tick) continues to operate normally(a pending 1 Hz tick can be lost). Restarting of communications begins with transfer of the START condition again.
Since when writing immediately to the four UNIX registers, a possibly memorized 1 Hz tick can be lost, it isrecommended to make a reset of the prescaler before setting the UNIX time (see RESET BIT FUNCTION). The 32bit UNIX counter value itself does not change during reset. The time between the reset and the I 2C STOP after writing
the UNIX time should be within 950 ms. See diagram below.
Advantage of this method: No 1 Hz tick will be lost during write access to the four UNIX registers.
 Prevents unwanted difference of one second between Seconds register and UNIX time.

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Example for setting the UNIX time using the reset function:
1 Hz CLKOUTor INT

1

UNIX Time 0
UNIX Time 1
UNIX Time 2

UNIX Time 3
1 s – 0 to 244 µs

1s

RESET/or Seconds

1s

2

I2C-bus3
Write operation

1

To monitor the synchronicity of the 1 Hz tick to an external clock source, the 1 Hz clock can be enabledon CLKOUT pin or on interrupt output pin ̅̅̅̅̅
INT. For both, the negative edge corresponds to the 1 Hz tick forthe clock counter increment (except the negative edge from reset).

2

Writing 1 to the RESET bit or writing to the Seconds register for a consistent and highly accurate time
adjustment (synchronization), and for the preparation for write access to the four UNIX registers without
losing a possibly memorized 1 Hz tick. The UNIX value is not changed right at this moment. The first 1 Hz
period after reset will be 0 to 244 µs shorter than 1 second. The RESET bit always returns 0 when read(see RESET BIT FUNCTION).

3

A new value is entered to the UNIX Time counter registers (UNIX Time 0 to UNIX Time 3). Note that I2C
STOP condition after writing to the UNIX registers does not provoke a synchronization of the 1 Hz tick.

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4.16.2. READING THE UNIX TIME
During I2C read access with an access time smaller than 950 ms the UNIX registers (UNIX Time 0 to UNIX Time 3)
are fully readable but not blocked. Like to the reading of the clock and calendar registers, after I2C STOP conditiona possibly memorized 1 Hz tick is realized.
Advantage of the memorized 1 Hz tick: After reading, one memorized 1 Hz tick is handled. The UNIX time is updated.
If the I2C read access takes longer than 950 ms the I2C bus interface is reset by the internal bus timeout function. In
this case all UNIX data that is read has a value of FFh, the pending 1 Hz tick is realized and the UNIX increment (1Hz tick) continues to operate normally. Restarting of communications begins with transfer of the START condition
again.
Two methods for reading the UNIX time are recommended:
1. Read the four registers (UNIX Time 0 to UNIX Time 3) twice and check for consistent results.
2. Generate 1 Hz interrupt on ̅̅̅̅̅
INT pin with PERIODIC TIME UPDATE INTERRUPT FUNCTION for the MCU,
when can be read. The time between the interrupt event and the I2C STOP after reading the UNIX timeshould be within 950 ms. No second reading needed.

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4.17. RESET BIT FUNCTION
The RESET bit is used for a software-based accurate and safe starting of the time circuits (synchronization). Writing
to the Seconds register has the same effect.
When writing 1 to the RESET bit or when writing to the Seconds register, the clock prescaler frequencies for 8192
Hz to 1 Hz are reset and an eventual present memorized 1 Hz update is also reset. The RESET bit always returns 0
when read. Because the upper stage of the prescaler is not reset (16.384 kHz) and the I2C interface is asynchronous,
the first 1 Hz period after reset will be 0 to 244 µs shorter than 1 second. Resetting the prescaler will have an influenceon the length of current clock period on all subsequent peripherals (clock and calendar, CLKOUT clock, timer clock,
update timer clock, UNIX clock, EVI input filter).
Writing 1 to the RESET bit or writing to the Seconds register will not affect the CLKOUT of the 32.768 kHz (see also
CLKOUT FREQUENCY SELECTION).

OSCILLATOR

F0

1 Hz

2 Hz

819 2 Hz32.768 kHz

16.384 kHz

Scheme of the reset function:

F1

F13

F14

RESET

RESET

RESET

0

1 Hz tick

1
RESET
Seconds (1)

1 Hz
32 Hz
64 Hz
1024 Hz8192 Hz32.768 kHz(1)

CLKOUT sour ce

When writing 1 to the RESET bit or when writing to the Seconds register has the same effect to theprescaler.

Procedure for setting the clock and calendar values using the RESET bit function:
1. Write the desired clock and calendar values within 950 ms to the registers (seconds, minutes, hours,
weekday, date, month and year).
2. Write 1 to the RESET bit or write a value to the Seconds register for a synchronized start of the time
circuits (1 Hz tick). The RESET bit always returns 0 when read.
See also sections SETTING THE TIME and SETTING THE UNIX TIME.

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Timing of the reset function:
1 Hz CLKOUTor INT

1

Seconds register(using RESET bit)A

Seconds register(writing to it)

A
1s

RESET/or Seconds

A+1

A+1

A+2

B

B+1

1 s – 0 to 244 µs

1s

2

A+3

B+2

A+4

C

C+1

1 s – 0 to 244 µs

1s

3

Write operation

1

2

3

To monitor the synchronicity of the 1 Hz tick to an external clock source, the 1 Hz clock can be enabledon CLKOUT pin or on the interrupt output pin ̅̅̅̅̅
INT. For both, the negative edge corresponds to the 1 Hz tickfor the clock counter increment (except the negative edge from reset).
Writing 1 to the RESET bit or writing to the Seconds register creates an immediate negative edge on the̅̅̅̅̅ pin. When writing 1 to the RESET bit the value in the Seconds register does
HIGH signal on CLKOUT or INT
not change right at this moment. RESET bit always returns 0 when read. The first 1 Hz period after reset willbe 0 to 244 µs shorter than 1 second.
Writing 1 to the RESET bit or writing to the Seconds register does not change the LOW signal on CLKOUT or̅̅̅̅̅
INT pin. The first 1 Hz period after reset will be 0 to 244 µs shorter than 1 second.

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4.18. USER PROGRAMMABLE PASSWORD
After a Power up and the first refreshment of tPREFR = ~66 ms, the Password PW registers (RAM 21h to 24h) arereset to 00h and the value in EEPWE (EEPROM 30h) and the values in the EEPROM Password EEPW registers(EEPROM 31h to 34h) are copied from the EEPROM to the corresponding RAM mirror.
The first four Password registers (PW), in case of the use of the function (enabled by writing 255 into the EEPROM
Password Enable register EEPWE), are used to write the 32-Bit Password necessary to be able to write in all writableregisters that have the convention WP (time, control, user RAM, configuration EEPROM and user EEPROM
registers). The 32-Bit Password PW is compared to the 32 bits stored in the RAM mirror of the EEPROM Password
EEPW (see PASSWORD REGISTERS, EEPROM PASSWORD ENABLE REGISTER and EEPROM PASSWORDREGISTERS).
Caution: The number of possible passwords is 232 ≈ 4.3 × 109 = 4.3 billion.

4.18.1. ENABLE/DISABLE WRITE PROTECTION
If the write protection function is enabled by writing 255 in register EEPWE (EEPROM 30h), it remains possible toread all the registers except the EEPROM registers. The EEPROM registers cannot be read because it cannot be
written to the EE Address and EE Command registers. If the function is not enabled, read and write are possible forall corresponding registers.
If the write protection function is enabled, it is necessary to first write the correct 32-Bit Password PW (PW = EEPW)
before any attempt to write in the RAM registers (Unlock), and to read and write in the EEPROM registers.
Once the user is finished with the write access and subsequently the write protection is still enabled or enabled again(by writing 255 in EEPROM register EEPWE), it is necessary to write an incorrect password (PW ≠ EEPW) into the
Password registers PW0 to PW3 in order to write-protect (Lock) the registers. See program sequences below and
FLOWCHART.
Enable write protection:
1. Initial state: WP-Registers are Not write-protected (EEPWE ≠ 255)
(Reference password is stored in the EEPROM Password EEPW)
2. Disable automatic refresh by setting EERD = 1
3. Enable password function by entering EEPWE = 255 (RAM)
4. Enter the correct password PW (PW = EEPW) to unlock write protection
5. Update EEPROM (all Configuration RAM  EEPROM) by writing EECMD = 00h followed by 11h
6. Enable automatic refresh by setting EERD = 0
7. Enter an incorrect password PW (PW ≠ EEPW) to lock the device
8. Final state: WP-Registers are Write-protected by password (EEPWE = 255)
Disable write protection:
1. Initial state: WP-Registers are Write-protected by password (EEPWE = 255)
(Reference password is stored in the EEPROM Password EEPW)
2. Enter the correct password PW (PW = EEPW) to unlock write protection
3. Disable automatic refresh by setting EERD = 1
4. Disable password function by entering EEPWE ≠ 255) (RAM)
5. Update EEPROM (all Configuration RAM  EEPROM) by writing EECMD = 00h followed by 11h
6. Enable automatic refresh by setting EERD = 0
7. Final state: WP-Registers are Not write-protected (EEPWE ≠ 255)
Hint: The EEPROM values of the reference password in the EEPROM Password EEPW registers can be READ with
the Read one EEPROM byte command (EECMD = 00h followed by 22h) when in Unlocked state (registers not writeprotected). This option is useful if it is not certain which password is written in the EEPW before the write protection
function is enabled. The RAM mirror from the EEPW registers can never be read.

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4.18.2. CHANGING PASSWORD
To code a new password, the user has to first enter the current (correct) Password PW (PW = EEPW) into theregisters 21h to 24h, if the WP-Registers are write protected, and then write a value not equal to all 1 (value ≠ 255)
in the EEPWE register (EEPROM 30h) to unlock write protection, and then write the new reference password EEPW
into the EEPROM registers 31h to 34h and writing all 1 (value = 255) in the EEPWE register to enable password
function. See program sequences below and FLOWCHART.
Change password if password function is enabled (EEPWE = 255):
1. Initial state: WP-Registers are Write-protected by old reference EEPROM Password EEPW
2. Enter old, correct password PW (PW = EEPW) to unlock write protection
3. Disable automatic refresh by setting EERD = 1
4. Disable password function by entering EEPWE ≠ 255 (RAM)5. Define a new reference password in the EEPW in registers (RAM)
6. Enable the password function by entering EEPWE = 255 (RAM)
7. Enter the correct password PW (PW = EEPW) to unlock write protection
8. Update EEPROM (all Configuration RAM  EEPROM) by writing EECMD = 00h followed by 11h
9. Enable automatic refresh by setting EERD = 0
10. Enter an incorrect password PW (PW ≠ EEPW) to lock the device
11. Final state: WP-Registers are Write-protected by new reference EEPROM Password EEPW
Change password if password function is disabled (EEPWE ≠ 255):
1. Initial state: Old reference password is stored in the EEPROM Password EEPW
2. Disable automatic refresh by setting EERD = 1
3. Define a new reference password in the EEPW registers (RAM)
4. Update EEPROM (all Configuration RAM  EEPROM) by writing EECMD = 00h followed by 11h
5. Enable automatic refresh by setting EERD = 0
6. Final state: New reference password is stored in the EEPROM Password EEPW
Note that the EEPROM password EEPW = 00000000h is not a real password, because after POR the password PW
is also 00000000h (PW = EEPW) and although the password function is enabled after POR refresh (EEPW = 255)
the PW-Registers are unlocked.

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4.18.3. FLOWCHART
The following flowchart describes the programming of the enabling and disabling of the register write protection byuser password and the changing of the user password and the other Configuration EEPROM registers (35h – 37h)
if write protection is enabled or disabled. In this example the Update EEPROM command (writing EECMD = 00hfollowed by 11h) is applied to write (store) data from all Configuration RAM mirror bytes (addresses 30h to 37h) into
the corresponding Configuration EEPROM bytes. See also USE OF THE CONFIGURATION REGISTERS.
User programmable password flowchart:

Edit all RAM(00h - 28h)

POR
(1)
EEPWE

255

WP-Registers are
Not write-protected

EERD = 0

EECMD = 00h&11h(RAM  EEPROM)

Enableautomatic refresh

No write
protection

UpdateEEPROM

Edit otherConfig. EEPROM(35h - 37h)

Disableautomatic refresh

EERD = 1

Enablepassword function

EEPWE = 255
(RAM)

(RAM)
EEPWE 255
(RAM)

Disablepassword function

Define new
password EEPW(RAM)
Edit otherConfig. EEPROM(35h - 37h)

(3)

(3)
UpdateEEPROM

EECMD = 00h&11h(RAM  EEPROM)(RAM)

EERD = 1

Enter correct PW(PW = EEPW)Disableautomatic refresh

Using write
protection

UnlockEnableautomatic refresh

Lock
POR

EERD = 0Enter incorrect PW(PW EEPW)(2)EEPWE = 255

WP-Registers are
Write-protected(1) Entry point after POR refresh when EEPWE ≠ 255.
(2) Entry point after POR refresh when EEPWE = 255.
(3) If a new reference password has previously been defined in the Password EEPW registers (RAM), the

new correct password PW (PW = EEPW) must be entered here in order to unlock the write protection.

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5. I2C INTERFACEThe I2C interface is for bidirectional, two-line communication between different ICs or modules. The RV-3028-C7 isaccessed at addresses A4h/A5h, and supports Fast Mode (up to 400 kHz). The I 2C interface consists of two lines:
one bi-directional data line (SDA) and one clock line (SCL). Both lines are connected to a positive supply via pull-up
resistors. Data transfer is initiated only when the interface is not busy.

5.1. BIT TRANSFER
One data bit is transferred during each clock pulse. The data on the SDA line remains stable during the HIGH periodof the clock pulse, as changes in the data line at this time are interpreted as a control signals. Data changes should
be executed during the LOW period of the clock pulse (see Figure below).
Bit transfer:
SDA
SCL
data line
stable;data validchange ofdataallowed5.2. START AND STOP CONDITIONSBoth data and clock lines remain HIGH when the bus is not busy. A HIGH-to-LOW transition of the data line, while
the clock is HIGH, is defined as the START condition (S). A LOW-to-HIGH transition of the data line, while the clock
is HIGH, is defined as the STOP condition (P) (see Figure below).
Definition of START and STOP conditions:

SDA

SDA

SCL

SCL
S

P

START condition

STOP condition

A START condition which occurs after a previous START but before a STOP is called a Repeated START condition,and functions exactly like a normal STOP followed by a normal START.
Caution:When communicating with the RV-3028-C7 module, the series of operations from transmitting the START condition
to transmitting the STOP condition should occur within 950 ms.
If this series of operations requires 950 ms or longer, the I2C-bus interface will be automatically cleared and set tostandby mode by the bus timeout function of the RV-3028-C7. Note with caution that both write and read operations
are invalid for communications that occur during or after this auto clearing operation. When writing: no acknowledge
will occur. When reading: FFh will be read.
Restarting of communications begins with transfer of the START condition again.
The I2C auto increment Address Pointer is neither reset by the I2C STOP condition nor by the internal stop forced
after timeout.

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5.3. DATA VALID
After a START condition, SDA is stable for the duration of the high period of SCL. The data on SDA may be changed
during the low period of SCL. There is one clock pulse per bit of data. Each data transfer is initiated with a START
condition and terminated with a STOP condition. The number of data bytes transferred between the START and
STOP conditions is not limited (however, the transfer time must be no longer than 950 ms). The information istransmitted byte-wise and each receiver acknowledges with a ninth bit.

5.4. SYSTEM CONFIGURATION
Since multiple devices can be connected with the I2C-bus, all I2C-bus devices have a fixed and unique device number
built-in to allow individual addressing of each device.
The device that controls the I2C-bus is the Master; the devices which are controlled by the Master are the Slaves. A
device generating a message is a Transmitter; a device receiving a message is the Receiver. The RV-3028-C7 acts
as a Slave-Receiver or Slave-Transmitter.
Before any data is transmitted on the I2C-bus, the device which should respond is addressed first. The addressing isalways carried out with the first byte transmitted after the START procedure. The clock signal SCL is only an input
signal, but the data signal SDA is a bidirectional line.
System configuration:SDA
SCLMASTER
TRANSMITTERRECEIVER

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RECEIVERSLAVE
TRANSMITTERRECEIVER

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5.5. ACKNOWLEDGE
The number of data bytes transferred between the START and STOP conditions from transmitter to receiver isunlimited (however, the transfer time must be no longer than 950 ms). Each byte of eight bits is followed by anacknowledge cycle.
 A slave receiver, which is addressed, must generate an acknowledge cycle after the reception of eachbyte.
 Also a master receiver must generate an acknowledge cycle after the reception of each byte that has beenclocked out of the slave transmitter.
 The device that acknowledges must pull-down the SDA line during the acknowledge clock pulse, so that
the SDA line is stable LOW during the HIGH period of the acknowledge-related clock pulse (set-up andhold times must be taken into consideration).
 A master receiver must signal an end of data to the transmitter by not generating an acknowledge cycle on
the last byte that has been clocked out of the slave. In this event the transmitter must leave the data line
HIGH to enable the master to generate a STOP condition.
Data transfer and acknowledge on the I2C-bus:
data output
by transmitter
not acknowledge
data output
by receiveracknowledge
SCL from
master1

2

START
condition

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9S
clock pulse for
acknowledgement

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5.6. SLAVE ADDRESS
On the I2C-bus the 7-bit slave address 1010010b is reserved for the RV-3028-C7. The entire I2C-bus slave address
byte is shown in the following table.
Slave address

R/W

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

1

0

1

0

0

1

0

Transfer data

Bit 0
1(R)

A5h (read)A4h (write)0(W)After a START condition, the I2C slave address has to be sent to the RV-3028-C7 device. The R/W bit defines the
direction of the following single or multiple byte data transfer. The 7-bit address is transmitted MSB first. If this address
is 1010010b, the RV-3028-C7 is selected, the eighth bit indicates a read ( R/W = 1) or a write ( R/W = 0) operation(results in A5h or A4h) and the RV-3028-C7 supplies the ACK. The RV-3028-C7 ignores all other address values
and does not respond with an ACK.
In the write operation, a data transfer is terminated by sending either the STOP condition or the START condition of
the next data transfer.

5.7. WRITE OPERATION
Master transmits to Slave-Receiver at specified address. The Register Address is an 8-bit value that defines which
register is to be accessed next. After writing one byte, the Register Address is automatically incremented by 1.
Master writes to slave RV-3028-C7 at specific address:
1) Master sends out the START condition.
2) Master sends out Slave Address, A4h for the RV-3028-C7; the R/W bit is a 0 indicating a write operation.
3) Acknowledgement from RV-3028-C7.
4) Master sends out the Register Address to RV-3028-C7.
5) Acknowledgement from RV-3028-C7.
6) Master sends out the Data to write to the specified address in step 4).
7) Acknowledgement from RV-3028-C7.
8) Steps 6) and 7) can be repeated if necessary.
The address is automatically incremented in the RV-3028-C7.
9) Master sends out the STOP Condition.
2S

SLAVE ADDRESS

3
0 A
R/W

1

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5

6

7

8

REGISTER ADDRESS

A

DATA

A

DATA

9
A

P

Acknowledge from RV-3028-C7

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5.8. READ OPERATION AT SPECIFIC ADDRESS
Master reads data from slave RV-3028-C7 at specific address:
1)
2)
3)
4)
5)
6)
7)
8)

Master sends out the START condition.
Master sends out Slave Address, A4h for the RV-3028-C7; the R/W bit is a 0 indicating a write operation.
Acknowledgement from RV-3028-C7.
Master sends out the Register Address to RV-3028-C7.
Acknowledgement from RV-3028-C7.
Master sends out the Repeated START condition (or STOP condition followed by START condition)
Master sends out Slave Address, A5h for the RV-3028-C7; the R/W bit is a 1 indicating a read operation.
Acknowledgement from RV-3028-C7.
At this point, the Master becomes a Receiver and the Slave becomes the Transmitter.
9) The Slave sends out the Data from the Register Address specified in step 4).
10) Acknowledgement from Master.
11) Steps 9) and 10) can be repeated if necessary.
The address is automatically incremented in the RV-3028-C7.
12) The Master, addressed as Receiver, can stop data transmission by not generating an acknowledge on thelast byte that has been sent from the Slave-Transmitter. In this event, the Slave-Transmitter must leave thedata line HIGH to enable the Master to generate a STOP condition.
13) Master sends out the STOP condition.
2S

SLAVE ADDRESS

3

5

6

7

REGISTER ADDRESSASSLAVE ADDRESS

R/W

0 A

4

8
1 A

9

10

11

12 13

DATA

A

DATA

A

P

R/W

1

Repeated
START
Acknowledge from RV-3028-C7

Acknowledge from MasterNo acknowledge from Master5.9. READ OPERATION
Master reads data from slave RV-3028-C7 immediately after first byte:
1) Master sends out the START condition.
2) Master sends out Slave Address, A5h for the RV-3028-C7; the R/W bit is a 1 indicating a read operation.
3) Acknowledgement from RV-3028-C7.
At this point, the Master becomes a Receiver and the Slave becomes the Transmitter.
4) The RV-3028-C7sends out the Data from the last accessed Register Address incremented by 1.
5) Acknowledgement from Master.
6) Steps 4) and 5) can be repeated if necessary.
The address is automatically incremented in the RV-3028-C7.
7) The Master, addressed as Receiver, can stop data transmission by not generating an acknowledge on thelast byte that has been sent from the Slave-Transmitter. In this event, the Slave-Transmitter must leave thedata line HIGH to enable the Master to generate a STOP condition.
8) Master sends out the STOP condition.
2

3

S

SLAVE ADDRESS

1 A

4

5

6

7

8

DATA

A

DATA

A

P

R/W

1

Acknowledge from RV-3028-C7

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5.10. I2C-BUS IN SWITCHOVER CONDITION
To save power when the RV-3028-C7 is in VBACKUP Power state the bus I2C-bus interface is automatically disabled(high impedance) and reset. Therefore the communication via I 2C interface should be terminated before the supply
is switched from VDD to VBACKUP. If the bus communication could not be completed properly, the I 2C read/write data
integrity is no longer guaranteed.
Note: If the I2C communication has ended in an uncontrolled manner, the I2C-bus interface has to be re-initialized bysending a STOP followed by a START after the device switched back from VBACKUP Power state to VDD Powerstate.

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Extreme Low Power Real-Time Clock Module

RV-3028-C7

6. ELECTRICAL SPECIFICATIONS
6.1. ABSOLUTE MAXIMUM RATINGS
The following Table lists the absolute maximum ratings.
Absolute Maximum Ratings according to IEC 60134:
SYMBOLPARAMETER

VDD
VI
VO
II
IO

Power Supply Voltage
Input voltage
Output voltage
Input current
Output current

VESD

ESD Voltage

ILU
TOPR
TSTO
TPEAK

Latch-up Current
Operating Temperature
Storage Temperature
Maximum reflow condition

CONDITIONS

MIN
-0.3
-0.3
-0.3
-10
-10

Input Pin
Output Pin

HBM(1)
CDM(2)
Jedec(3)-40-55
JEDEC J-STD-020C

TYP

MAX

UNIT

6.0
VDD +0.3
VDD +0.3
10
10
±2000
±500
±100
85
125
265

V
V
V
mA
mA
V
V
mA
°C
°C
°C

(1) HBM: Human Body Model, according to JS-001.
(2) CDM: Charged-Device Model, according to JEDEC JS-002-201X.
(3) Latch-up testing, according to JESD78., Class I (room temperature), level A (100 mA)

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Extreme Low Power Real-Time Clock Module

RV-3028-C7

6.2. OPERATING PARAMETERS
For this Table, TA = -40 to +85°C unless otherwise indicated. VDD = 1.2 to 5.5 V, TYP values at 25°C and 3.0 V.
Operating Parameters:
SYMBOLPARAMETERCONDITIONS

MIN
1.1

Power Supply Voltage

Time-keeping mode(1)Minimum time-keeping
voltage(1)I2C-bus (100 kHz)
I2C-bus (400 kHz)

TYP

MAX

UNIT

Supplies

VDD

VBACKUP

Backup Supply Voltage= 1.1 V(2), T

IDD

IDD:I2C

IDD:DSM

IDD:LSMIBACKUP:DSM
IBACKUP:LSM

VDD supply current timekeeping
I2C-bus inactive, CLKOUT
disabled, average current

VDD supply current during
I2C burst read/write, CLKOUT
disabled
VDD supply current in Direct
Switching Mode
I2C-bus inactive, CLKOUT
disabled
VDD supply current in Level
Switching Mode
I2C-bus inactive, CLKOUT
disabled
VBACKUP supply current in Direct
Switching ModeVBACKUP supply current in Level
Switching ModeΔIDD:CK32
ΔIDD:CK1024

Additional VDD supply current(4)ΔIDD:CK1

VDD
A = 25°C
VDD = 3.0 V(2), TA = 25°C
VDD = 5.0 V(2), TA = 25°C
VDD = 1.1 V(2),TOPR = -40 to +85°C
VDD = 3.0 V(2),TOPR = -40 to +85°C
VDD = 5.0 V(2),TOPR = -40 to +85°C
VDD = 1.2 V, SCL = 100 kHz(3)VDD = 3.0 V, SCL = 400 kHz(3)VDD = 5.0 V, SCL = 400 kHz(3)

5.5
0.9

1.1

45
45
45

5.5
5.5
5.5
60
60
66

1.2
2.0
1.1

300

V

nA

330
400
2
5
7

15
40
60

VDD = 3.0 V, TA = 25°C,
VBACKUP < VDD

95

150

VDD = 3.0 V, TA = 25°C

115

180

95

150

115

180

VBACKUP = 3.0 V, TA = 25°C,
VDD < VBACKUPVBACKUP = 3.0 V, TA = 25°C,
VDD < VTH:LSM (2.0 V)
VDD = 3.0 V, FCLKOUT = 32.768
kHz, CL = 10 pF
VDD = 3.0 V, FCLKOUT = 1024 Hz,
CL = 10 pF
VDD = 3.0 V, FCLKOUT = 1 Hz,
CL = 10 pF

V

1

µA

nA

µA

30
nA
0.03

(1) Clocks operating and RAM registers retained.
(2) All inputs and outputs are at 0 V or VDD.

(3) 2.2 kΩ pull-up resistors on SCL/SDA, excluding external peripherals and pull-up resistor current. All other inputs (besides SDA and SCL)

are at 0 V or VDD. Test conditions: Continuous burst read/write, 55h data pattern, 25 μs between each data byte, 20 pF load on each buspin.
(4) When CLKOUT is enabled the additional V supply current ΔI can be calculated as follows:
DD
DD
ΔIDD = CL x VDD x fOUT, e.g. ΔIDD = 10 pF x 3.0 V x 32’768 Hz = 980 nA ≈ 1 µA

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Extreme Low Power Real-Time Clock Module

RV-3028-C7

For this Table, TA = -40 to +85°C unless otherwise indicated. VDD = 1.2 to 5.5 V, TYP values at 25°C and 3.0 V.
Operating Parameters (continued):
SYMBOLPARAMETER

InputsVIH
VIL
IILEAK

HIGH level input voltage
LOW level input voltage
Input leakage current

CI

Input capacitance

CONDITIONSMINVDD = 1.1 V to 5.5 V
Pins: SCL, SDA, EVI

0.8 VDD

VSS ≤ VI ≤ VDD
VDD = 3.0 V, TA = 25°C
f = 1 MHz

-0.5

VDD = 1.1 V, IOH = -0.1 mA
VDD = 3.0 V, IOH = -1.0 mA
VDD = 5.0 V, IOH = -1.0 mA
VDD = 1.1 V, IOL = 0.1 mA
VDD = 3.0 V, IOL = 1.0 mA
VDD = 5.0 V, IOL = 1.0 mA
VDD = 1.2 V, IOL = 0.5 mA
VDD = 3.0 V, IOL = 3.0 mA
VDD = 5.0 V, IOL = 3.0 mA
VO = VDD or VSS
VDD = 3.0 V, TA = 25°C
f = 1 MHz

1.0
2.7
4.5

TYP

MAX

UNIT

0.2 VDD
0.5

V
V
µA

7

pF

Outputs
VOH:CLKHIGH level output voltage
CLKOUT

VOL:CLK

LOW level output voltage
CLKOUTVOL

LOW level output voltage
̅̅̅̅̅
Pins: SDA, INTIOLEAK

Output leakage current

COUT

Output capacitancePower On Reset
VPOR
POR detection threshold
Trickle charger
TCR 3 kΩTCR 5 kΩ
Current limiting resistor
TCR 9 kΩTCR 15 kΩ
VF
Schottky diode voltage drop
Switchover

VDD = 5.0 V, VBACKUP = 3.0 V,
including internal schottky diode

VHYST:DSM

Switchover hysteresis in Direct
Switching ModeVDD with respect to VBACKUP = 3.0
V, VDD slew rate = ±1 V/ms
TOPR = -40 to +85°C

VTH:LSM

Backup switchover thresholdvoltage in Level Switching ModeVDD falls below VTH:LSM

VHYST:LSM

Switchover hysteresis in Level
Switching ModeVDD with respect to VBACKUP = 3.0
V, VDD slew rate = ±1 V/ms
TOPR = -40 to +85°C

EEPROM Characteristics
VDD:READ
VDD read voltage
VDD:WRITEVDD write voltage
tPREFRPOR refresh time
tAREFR
Automatic refresh timetUPDATE
Update time
tREFR
Refresh timetWRITE
Write to one EEPROM byte time
tREAD
Read one EEPROM byte timenCYCLE

Write cycle endurance(1)tRETData retention time(1)

V

-0.5

0.1
0.3
0.5
0.4
0.4
0.3
0.5

µA

7

pF

At power up
Each 24 hours, EERD = 0
EECMD = 11h
EECMD = 12h
EECMD = 21h
EECMD = 22h
VDD = 3.0 V, TA = 25°C
VDD = 5.5 V, TA = 85°C
TA = 55°C

V

0.75

0.8

0.85

V

2
4.5
7.5
12.5

3
5.5
9.3
15.5
0.25

4
6.25
11.6
17.4

kΩ

V

60
1.8

2.0

mV
2.2

100

4
10’000
100
10

V
mV

1.1
1.5

VDD Power state

V

V
66
3.5
63
3.5
16
1.4

ms
30

cyclesyears(1) Guaranteed by indirect testing.

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Extreme Low Power Real-Time Clock Module

RV-3028-C7

6.2.1.TYPICAL CHARACTERISTICS
Typical characteristics for Direct Switching Mode (DSM), Level Switching Mode (LSM) and switchover disabled:
For these diagrams, I2C-bus inactive, CLKOUT disabled.

IBACKUP versus VBACKUP, VDD = 0 V, TA = 25°C
(after turning off VDD)

300

300

250

250

200

200

switchover

150

LSM

*

100

IBACKUP [nA]

IDD [nA]

IDD versus VDD, VBACKUP = 0 V, TA = 25°C

LSM

150
100

DSM

DSM
50

50
switchoverdisabled

0
0

1

2

4

3

5

switchoverdisabled

0
6

0

1

2

5

IBACKUP versus TA, VBACKUP = 3 V, VDD = 0 V(after turning off VDD)

300

300

250

250

200

200

IBACKUP [nA]

IDD versus TA, VDD = 3 V, VBACKUP = 0 V

150

LSM

100

DSM

50

0
-50

0

25

50

75

LSM

100

0
-50

100

DSM

switchoverdisabled
-25

0

25

50

75

100

TA [°C]TA [°C]

November 2021

150

50

switchoverdisabled-25

6

VBACKUP [V]

VDD [V]

IDD [nA]

4

3

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Extreme Low Power Real-Time Clock Module

RV-3028-C7

6.3. OSCILLATOR PARAMETERS
For this Table, TA = -40 to +85°C unless otherwise indicated. VDD = 1.2 to 5.5 V, TYP values at 25°C and 3.0 V.
Oscillator Parameters:
SYMBOLPARAMETER

Xtal General
F

CONDITIONS

MIN

TYP

Crystal Frequency

VSTART

Oscillator start-up voltage
Frequency vs. voltage
characteristics

Δf/V
VDDR

VDD rising slew rate

VDDF

VDD falling slew rate

δCLKOUT

CLKOUT duty cycle

32.7680.2

TA = 25°C

Oscillator start-up time at
VDD = 3.0 V

tSTART

MAX

kHz
1
3

1.3

TA = 25°C
TOPR = -40 to +85°C
VDD = 3.0 V

0.5

Calibrated at an initial
temperature and voltage
Calibrated at TA = 25°C,
VDD = 3.0 V

1

ppm/V

2.5
3.8
2.2

V/ms

50 ±10%±5ppm-0.035ppm/°C2 (TOPR-T0)2 ±10%ppm

+25 ±5°C
ppm

TA = 25°C, VDD = 3.0 V

TA = -40 to +85°CsV

VDD = 1.1 V to 5.5 V
TA = 25°C
VDD = 1.1 V to 3.6 V
VDD = 3.6 V to 5.5 V
VDD = 5.5 V to 1.1 V
VDD = 1.1 V to 5.5 V
FCLKOUT = 32.768 kHz

Xtal Frequency Characteristics
ΔF/F
Frequency accuracy
Frequency vs. temperature
ΔF/FTOPR
characteristics
T0
Turnover temperature
ΔF/F
Aging first year max.
Xtal Frequency Offset Correction
EEOffset correction:
Δt/tMin. corr. step (LSB) andMax. corr. range
EEOffset. Achievable timeΔt/taccuracy.
EEOffset. Factory Calibrated
Δt/ttime accuracy.

UNIT

±3

±0.954+243.2/-244.1

ppm

-0.48

+0.48

ppm

±1

ppm

6.3.1.XTAL FREQUENCY VS. TEMPERATURE CHARACTERISTICS

20
T0 = 25°C (± 5°C)
0-20

f/f [ppm]

-40
-60
-80
-0.035 * (T-T0)2 ppm (±10%)

-100
-120
-140
-160
-180
-50

November 2021

-40

-30

-20

-10

0

10

20
30
40
Temperature [°C]

100/116

50

60

70

80

90

Rev. 1.4

Micro Crystal
Extreme Low Power Real-Time Clock Module

RV-3028-C7

6.4. POWER ON AC ELECTRICAL CHARACTERISTICS
The following Figure describes the power on AC electrical characteristics for the CLKOUT pin. The clock output signal
on CLKOUT pin is primarily controlled by the CLKOE bit (EEPROM 35h), the CLKF flag and the FD field (EEPROM
35h). See also CLOCK OUTPUT SCHEME and USE OF THE CONFIGURATION REGISTERS.
Power On AC Electrical Characteristics:
VDD

PORF

VPOR

VDDR1

1

5

EEbusy3
2

4

CLKOUTtREFRtSTART
State

POR

OperatingWrite operation

1

Flag PORF and the EEbusy status bit are set when VDD starting from below VPOR.
Regardless of the settings in the EEPROM 35h, CLKOUT pin is driving always the frequency of 32.768 kHz
during the first refreshment time tPREFR = ~66 ms.
3
After tPREFR, EEbusy is cleared to 0 automatically. The typical start up time tSTART is 0.2 s.
4
Depending of the settings of the CLKOE bit (EEPROM 35h) and/or the CLKF flag and the FD field (EEPROM
35h) the CLKOUT pin can drive the following signals:
 Square wave of 32.768 kHz (default value on delivery), 8192 Hz, 1024 Hz, 64 Hz, 32 Hz or 1 Hz,
 Or the predefined periodic countdown timer interrupt (FD = 110). CLKOUT is immediately set to
HIGH level. The Periodic Countdown Timer itself has to be started by software.
 When CLKOE bit and CLKF flag are 0 or when FD field is 111 or when the device goes to VBACKUPPower state, the CLKOUT signal is set to LOW level.
5
The PORF flag remains 1 until it is cleared to 0 by software.
2

For this Table, TA = -40 to +85°C and VDD = 1.2 to 5.5 V, TYP values at 25°C and 3.0 V.
Power On AC Electrical Parameters:
SYMBOLVDDR1tSTARTVSTARTtPREFR

November 2021

PARAMETER
VDD rising slew rate at initial
power on reset (POR)
Oscillator start-up time at
VDD = 3.0 V

CONDITIONS

MIN

TYP

0.1
TA = 25°C

Oscillator start-up voltage
First refreshment time

0.2
1.3
66

101/116

MAX

UNIT

1

V/ms

1
3

s
V
ms

Rev. 1.4

Micro Crystal
Extreme Low Power Real-Time Clock Module

RV-3028-C7

6.5. I2C-BUS CHARACTERISTICS
The following Figure and Table describe the I2C AC electrical parameters.
I2C AC Parameter Definitions:

SDA

t BUF
t LOW

t HD:DATt SU:DATSCLt HD:STAt HIGHt RISEPt FALLSt SU:STOt SU:STA

SDA

Sr

P

For the following Table, TA = -40 to +85°C.
I2C AC Electrical Parameters:
SYMBOL
fSCL
tLOW
tHIGH
tRISE
tFALL
tHD:STAtSU:STAtSU:DATtHD:DATtSU:STOtBUF

PARAMETER
SCL input clock frequency
Low period of SCL clock
High period of SCL clock
Rise time of SDA and SCL
Fall time of SDA and SCL
START condition hold time
START condition setup time
SDA setup time
SDA hold time
STOP condition setup time
Bus free time before a new transmission

VDD ≥ 1.2 V

VDD ≥ 2.0 V

MIN

MAX

MIN

MAX

0
4.7
4.0

100

0
1.3
0.6

400

1000
300
4.0
4.7
250
0
4.0
4.7

300
300
0.6
0.6
100
0
0.6
1.3

UNIT
kHz
µs
µs
ns
ns
µs
µs
ns
µs
µs
µs

S = Start condition, Sr = Repeated Start condition, P = Stop condition

Caution:When accessing the RV-3028-C7, all communication from transmitting the Start condition to transmitting the Stopcondition after access should be completed within 950 ms.
If such communication requires 950 ms or longer, the I2C-bus interface is reset by the internal bus timeout function.

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Extreme Low Power Real-Time Clock Module

RV-3028-C7

7. TYPICAL APPLICATION CIRCUITS
7.1. NO BACKUP SOURCE / EVENT INPUT NOT USED
Application Key Points:●●●

No VBACKUP source
Lowest current consumption (45 nA typ.)
CLKOUT settings stored in EEPROM for permanent configuration

Register Configuration:
0.

RTC with default configuration on delivery (bits in black)
CLKOE
FDRegister 35h
X
1
0
0
0
X
X
X
CLKOUT settings (35h) to be stored in EEPROM using procedure of 4.6.3.

1.
2.

CLKOE → CLKOUT to be set
FD → Frequency to be selected

100 nF

2

4
VDD

VDD

RV-3028-C7
VBACKUP

1

VDD

MCU

SDA

SDA

SCL

SCL

EVI
10 k

6
INT
10 k

1

2
3
4
5
6

3

5

CLKOUT

VSS

VSS

Backup Switchover functionality is disabled by default. Do not leave VBACKUP power supply pin floating.
Connection to VSS through a 10 kΩ resistor keeps functional test possible.
100 nF decoupling capacitor close to the device.
Interrupts are disabled by default.
̅̅̅̅̅ pin is an open-drain output, which can be left open when not used.
INT
I2C lines SCL, SDA are open-drain and require pull-up resistors to VDD.
CLKOUT with a frequency of 32.768 kHz (*) is enabled by default (default value on delivery).
If not used, disable CLKOUT to minimize current consumption (CLKOE = 0 and CLKF = 0, or FD = 111).
External Events functionality is disabled by default. Do not leave EVI input pin floating.
Connection to VSS through a resistor keeps functional test possible.

(*) CLKOUT offers the selectable frequencies 32.768 kHz (default), 8192 Hz, 1024 Hz, 64 Hz, 32 Hz or 1 Hz,or the predefined periodic countdown Timer Interrupt for application use.

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Extreme Low Power Real-Time Clock Module

RV-3028-C7

7.2. NON-RECHARGEABLE BACKUP SOURCE / EVENT INPUT USED (ACTIVE HIGH)
Application Key Points:●●●●

Trickle charger disabled to avoid dangerous charging current into the backup source
LSM Backup Switchover Mode to avoid non-desired backup switching (VTH:LSM = 2.0 V)
Power Management settings have to be stored in EEPROM for permanent configuration
Rising edge or high-level voltage applied to the EVI input triggers an interrupt

Register Configuration:
0.
1.

2.

RTC with default configuration on delivery (bits in black)
0
0
0
0
0
1
0
0
Register 10h
EHL
ETRegister 13h
0
1
X
X
0
0
0
0
TCE
BSM
Register 37h
0/1
0
0
1
1
1
0
0
Switchover settings (37h) to be stored in EEPROM using procedure of 4.6.3.

EIE → Event interrupt enabled
EHL → Event-high detection
ET → Event filtering to be set
TCE → Trickle charger disabled
BSM → LSM switchover mode

VBACKUP
100 nF

6
VBACKUP

2

VDD

RV-3028-C7MCU

2100 nF4VDD

VBACKUP

1

3

INT

INT

SDA

SDA

SCL

SCL

VDD

EVI

5

CLKOUT
Primary
Battery

VSS

VSS

10 k

1

2
3
4
5

6

Insert a protection resistor of 100 – 1000 Ω to prevent damage in case of soldering issues causing short
between supply pins.
100 nF decoupling ceramic capacitor close to the device for VDD and VBACKUP.
The ̅̅̅̅̅
INT signal also works when the device operates on VBACKUP supply voltage.
In that case, it is possible to tie the ̅̅̅̅̅
INT signal pull-up resistor to VBACKUP.
I2C lines SCL, SDA are open-drain and require pull-up resistors to VDD.
CLKOUT is disabled in VBACKUP Power state. If not used in VDD Power state, disable CLKOUT to minimize
current consumption (CLKOE = 0 and CLKF = 0, or FD = 111).
EVI input set to detect rising edge or high-level of tamper detection signal;
The EVI input is never floating thanks to the 10 kΩ to VSS.

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Extreme Low Power Real-Time Clock Module

RV-3028-C7

7.3. RECHARGEABLE BACKUP SOURCE / EVENT INPUT USED (ACTIVE LOW)
Application Key Points:●●●●

MLCC, Supercap or Rechargeable Battery as secondary VBACKUP source
DSM Backup Switchover Mode for capacitors (or LSM for rechargeable battery)
Backup source charged through the trickle charger
Power Management settings have to be stored in EEPROM for permanent configuration

Register Configuration:
0.
1.

2.

RTC with default configuration on delivery (bits in black)
0
0
0
0
0
1
Register 10h
EHL
ETRegister 13h
0
0
X
X
0
0
TCE
BSM
Register 37h
0/1
0
1
1
0
1

0

0

0

0
TCR

X

X

EIE → Event interrupt enabled
EHL → Event-low detection
ET → Event filtering to be set
TCE → Trickle charger enabled
BSM → DSM switchover mode
TCR → Trickle resistor to be set

Switchover settings (37h) to be stored in EEPROM using procedure of 4.6.3.

VBACKUP
100 nF

3

10 k

2
VBACKUP

VDD

VDD

RV-3028-C7MCU

VBACKUP
100 nF

2

1

4

INT

INT

SDA

SDA

SCL

SCL

EVI

5

CLKOUT

Supercap or
Rechargeable
Battery

1

2

6

VSS

VSS

Low-cost MLCC (*) ceramic capacitor, supercapacitor (e.g. 1 farad) or secondary battery LMR(respect manufacturer specifications for constant charging voltage).
When Lithium Battery is used, it is recommended to insert a protection resistor of 100 – 1000 Ω. to limit
battery current and to prevent damage in case of soldering issues causing short between supply pins.
100 nF decoupling ceramic capacitor close to the device for VDD and VBACKUP.

3̅̅̅̅̅ signal also works when the device operates on VBACKUP supply voltage.
The INTIn that case, it is possible to tie the ̅̅̅̅̅
INT signal pull-up resistor to VBACKUP.

4

I2C lines SCL, SDA are open-drain and require pull-up resistors to VDD.

5

VDD

CLKOUT is disabled in VBACKUP Power state. If not used in VDD Power state, disable CLKOUT to minimize
current consumption (CLKOE = 0 and CLKF = 0, or FD = 111).

6 EVI input set to detect falling edge or low-level of tamper detection signal;
The EVI input is never floating thanks to the 10 kΩ to VDD.
(*) Note, that low-cost MLCCs are normally used for short time keeping (minutes) and the more
expensive supercapacitors for a longer backup time (days - weeks).
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Extreme Low Power Real-Time Clock Module

RV-3028-C7

7.4. NO BACKUP SOURCE / EVENT INPUT USED (“WAKE-UP”& “POWER SWITCH”)
Application Key Points:●●●●

No VBACKUP source and lowest current consumption (45 nA typ.)External Event enabled allowing RTC to fire “wake-up” interrupt acting on load switch
MCU most of the time in idle mode is awaken by RTC’s interrupt through the upper load switch
MCU holds supply voltage until its task is finished and cuts off its own supply voltage

Register Configuration:
0.
1.

RTC with default configuration on delivery (bits in black)
0
0
0
0
0
Register 10h
EHL
ETRegister 13h
0
1
X
X
0

1

0

0

0

0

0

EIE → Event interrupt enabled
EHL → Event-high detection
ET → Event filtering to be set

Power Switch

VDD

VIN

VOUT

ON

GND

VIN

VOUT

GND

ON

Wake up !

100 nF

6
2

Hold !

3

VDD
Application
Wake up !

10 k

VDD
GPIO

INT

INT

SDA

SDA

SCL

SCL

VBACKUP CLKOUT
VSS

4

8

RV-3028-C7
EVI

1

HI
LO

MCU

7 UserWake up !

5

VSS

10 k

1

Backup Switchover functionality is disabled by default. Do not leave VBACKUP power supply pin floating.
Connection to VSS through a 10 kΩ resistor keeps functional test possible.

2

100 nF decoupling capacitor close to the device.

3

̅̅̅̅̅
INT pin is an open-drain output and requires a pull-up resistor.

4

I2C lines SCL, SDA are open-drain and require pull-up resistors to VDD.

5Disable CLKOUT to minimize current consumption (CLKOE = 0 and CLKF = 0, or FD = 111).

6 EVI input set to detect rising edge or high-level of tamper detection signal; can be used as an Application
Wake-Up signal. The EVI Input is never floating thanks to the 10 kΩ to VSS.

7 User or Manual Wake-Up, always available; e.g for initial system power-on to configure RTC and system.
8 MCU Power Retention via GPIO = High maintains MCU Power to complete I2C Interface communication
with the RTC. MCU cuts-off it’s own supply voltage by set GPIO = Low at the very end of its task.

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8. PACKAGE
8.1. DIMENSIONS AND SOLDER PAD LAYOUT
RV-3028-C7 Package:
Package dimensions (bottom view):
3,2Recommended solder pad layout:
0,9
0,9
0,9
0,5

4

8

7

6

5

0,4
0,8

2,0

3

0,5

2

1,5

1

0,8

0,9

0,4

0,8 max

0,15

3,2

Metal lid is connected to VSS (pin #5)
Tolerances:
Drawing:

unless otherwise specified ±0.1mm
RV-3028-C7_Pack-drw_20180208

All dimensions in mm typical.

8.1.1.RECOMMENDED THERMAL RELIEF
When connecting a pad to a copper plane, thermal relief is recommended.
RV-C7 Package:
GOOD

BAD

P
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8.2. MARKING AND PIN #1 INDEX
Laser marking RV-3028-C7 Package: (top view)

Product Date Code#8

M039A1#5

M039A13028#1

M
Micro Crystal

0
Year

39
Week

A1
Batch

#4
Part Designation

Pin 1 Index

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9. MATERIAL COMPOSITION DECLARATION & ENVIRONMENTAL INFORMATION
9.1. HOMOGENOUS MATERIAL COMPOSITION DECLARATION
Homogenous material information according to IPC-1752 standard
Material Composition RV-3028-C7:
4

5

2

1

8
3
6
7

(Symbolic drawing)
No.

Item
Component
Name

Sub ItemMaterial
Name

Material
Weight
(mg)
(%)

1
2

Resonator
Electrodes

Quartz Crystal
Cr+Au

0.13

3
4

Housing
Metal Lid

Ceramic
Kovar Lid

6.90

0.01

100%
6%
94%
100%
95%

Substance
Element
SiO2
Cr
Au
Al2O3
Fe53Ni29Co18

2.67

5

Seal

6

Terminations

7

Conductive
adhesive

Ni-plating
Au-plating
Solder Preform
Internal and externalterminals

0.54
0.38

Silver filled Silicone
glue

4.95%
0.05%
80%
20%
80%
15%
5%
88%
12%

0.09
0%

8

CMOS IC

November 2021

SiliconGold bumps

0.64

Unit weight

11.4

90%
10%

Ni
Au
Au80 / Sn20
Mo
Ni
Au 0.5 micron
Ag
Siloxanes andsilicones
Distillates, petroleumhydrotreatedSi
Au

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CAS
Number

Cr:
Au:
Fe:
Ni:
Co:
Ni:
Au:
Au:
Sn:
Mo:
Ni:
Au:
Ag:

14808-60-7
7440-47-3
7440-57-5
1344-28-1
7439-89-6
7440-02-0
7440-48-4
7440-02-0
7440-57-5
7440-57-5
7440-31-5
7439-98-7
7440-02-0
7440-57-5
7440-22-4
68083-19-2
64742-47-8

Si:
Au:

Comment

Metal Lid (Kovar)
Nickel platingGold plating

Molybdenum
Nickel platingGold plating
di-Me, vinyl groupterminatedDoes not appear infinished product7440-21-3
7440-57-5

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9.2. MATERIAL ANALYSIS & TEST RESULTS
Homogenous material information according to IPC-1752 standard
No.
Item
Sub Item
RoHS
Component
Material
Name
Name

Cd

Hg

Cr(VI)

PBB

PBDE

F

CI

Br

I

BBP

DBP

DEHP

DIBP

Phthalates

Pb

Halogens

1

Resonator

Quartz Crystal

nd

nd

nd

nd

nd

nd

nd

nd

nd

nd

nd

nd

nd

nd

2

Electrodes

Cr+Au

nd

nd

nd

nd

nd

nd

nd

nd

nd

nd

nd

nd

nd

nd

3

Housing

Ceramic

nd

nd

nd

nd

nd

nd

nd

nd

nd

nd

nd

nd

nd

nd

4

Metal Lid

Kovar Lid & Plating

nd

nd

nd

nd

nd

nd

nd

nd

nd

nd

nd

nd

nd

nd

5

Seal

Solder Preform

nd

nd

nd

nd

nd

nd

nd

nd

nd

nd

nd

nd

nd

nd

6

Terminations

Int. & ext. terminals

nd

nd

nd

nd

nd

nd

nd

nd

nd

nd

nd

nd

nd

nd

7

Conductive
adhesive

Silver filled Silicone glue

nd

nd

nd

nd

nd

nd

nd

nd

nd

nd

nd

nd

nd

nd

8

CMOS IC

Silicon & Gold bumps

nd

nd

nd

nd

nd

nd

nd

nd

nd

nd

nd

nd

nd

nd

MDL [ppm]

Method Detection Limit

2

8

5

50

50

nd (not detected) = below “Method Detection Limit” (MDL)
Test methods:
RoHS Pb, Cd
 Hg
 Cr(VI) PBB / PBDE
Halogens
Phthalates

November 2021

Test method with reference to:
IEC 62321-5:2013
IEC 62321-4:2013 + AMD1:2017
IEC 62321-7-2:2017
IEC 62321-6:2015
Test method with reference to BS EN 14582:2016
Test method with reference to IEC 62321-8:2017

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MDL:
MDL:
MDL:
MDL:
MDL:
MDL:

2 ppm
2 ppm
8 ppm
5 ppm
50 ppm50 ppmRev. 1.4

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Extreme Low Power Real-Time Clock Module

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9.3. RECYCLING MATERIAL INFORMATION
Recycling material information according to IPC-1752 standard.
Element weight is accumulated and referenced to the unit weight of 11.4 mg.
Item
No.
Item
Material
Substance
Material
Component
WeightElement
Name
Name
(mg)
(%)
Quartz Crystal
Chromium
Ceramic

1
2
3

Resonator
Electrodes
Housing

Gold

2
4
5
6
8
5
4
6

Electrodes
Metal Lid
Seal
Terminations
CMOS IC
Seal
Metal Lid
Terminations

6
4

Terminations
Metal Lid

Tin
Nickel
Molybdenum
Kovar

SilverSiloxanes andsilicones
Distillates

Silicon7a
7b

Conductive adhesive
Conductive adhesive

7cConductive adhesive

8

CMOS IC

Unit weight (total)

November 2021

CAS
Number

0.13
0.0006
6.90

1.14
0.005
60.74

SiO2
Cr
Al2O3

Cr:

14808-60-7
7440-47-3
1344-28-1

0.53

4.63

Au

Au:

7440-57-5

0.11

0.95

Sn

Sn:

7440-31-5

0.19

1.67

Ni

Ni:

7440-02-0

0.3

2.68

Mo

2.53

22.33

Fe53Ni29Co18

0.079

0.7

7439-98-7
7439-89-6
7440-02-0
7440-48-4
7440-22-4

0.011

0.10

Ag
Siloxanes andsilicones

Mo:
Fe:
Ni:
Co:
Ag:

0

0

0.58

5.07

11.4

100

68083-19-2

Distillates
Si

111/11664742-47-8
Si:

Comment

di-Me, vinyl groupterminatedhydrotreatedpetroleum, does notappear in finishedproducts

7440-21-3

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Micro Crystal
Extreme Low Power Real-Time Clock Module

RV-3028-C7

9.4. ENVIRONMENTAL PROPERTIES & ABSOLUTE MAXIMUM RATINGS
PackageSON-8 (DFN-8) ceramic
package
Parameter
Product weight (total)
Storage temperature
Moisture sensitivity level (MSL)FIT / MTBF

Description
Small Outline Non-leaded (SON), hermetically sealed ceramic package with metal lid.

Directive

Conditions
Store as bare product

IPC/JEDEC J-STD-020D

Value
11.4 mg-55 to +125°C
MSL1
available on request

Terminal finish:

NickelGold

November 2021

112/1160.5 µmMolybdenum

5 µm

Ceramic

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Extreme Low Power Real-Time Clock Module

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10. SOLDERING INFORMATION
Maximum Reflow Conditions in accordance with IPC/JEDEC J-STD-020C “Pb-free”

tP

TP

Critical Zone
TL to TP

TemperatureRamp-up

TL

tL

Tsmax

Tsmin
Ramp-downtsPreheat25

t 25°C to Peak

Temperature Profile
Average ramp-up rate
Ramp down Rate
Time 25°C to Peak Temperature
PreheatTemperature min
Temperature max
Time Tsmin to Tsmax
Soldering above liquidus
Temperature liquidus
Time above liquidus
Peak temperature
Peak Temperature
Time within 5°C of peak temperature

November 2021

Time
Symbol(Tsmax to TP)
Tcool
Tto-peakCondition
3°C / second max
6°C / second max
8 minutes max

Unit°C / s°C / s
min

Tsmin
Tsmax
ts

150
200
60 – 180

°C
°C
sec

TL
tL

217
60 – 150

°C
sec

Tp
tp

260
20 – 40°C
sec

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11. HANDLING PRECAUTIONS FOR MODULES WITH EMBEDDED CRYSTALSThe built-in tuning-fork crystal consists of pure Silicon Dioxide in crystalline form. The cavity inside the package isevacuated and hermetically sealed in order for the crystal blank to function undisturbed from air molecules, humidity
and other influences.
Shock and vibration:
Keep the crystal / module from being exposed to excessive mechanical shock and vibration. Micro Crystal
guarantees that the crystal / module will bear a mechanical shock of 5000 g / 0.3 ms.
The following special situations may generate either shock or vibration:
Multiple PCB panels - Usually at the end of the pick & place process the single PCBs are cut out with a router.
These machines sometimes generate vibrations on the PCB that have a fundamental or harmonic frequency close
to 32.768 kHz. This might cause breakage of crystal blanks due to resonance. Router speed should be adjusted
to avoid resonant vibration.
Ultrasonic cleaning - Avoid cleaning processes using ultrasonic energy. These processes can damage thecrystals due to the mechanical resonance frequencies of the crystal blank.
Overheating, rework high temperature exposure:
Avoid overheating the package. The package is sealed with a seal ring consisting of 80% Gold and 20% Tin. The
eutectic melting temperature of this alloy is at 280°C. Heating the seal ring up to >280°C will cause melting of themetal seal which then, due to the vacuum, is sucked into the cavity forming an air duct. This happens when using
hot-air-gun set at temperatures >280°C.
Use the following methods for rework:

Use a hot-air-gun set at 270°C.
Use 2 temperature controlled soldering irons, set at 270°C, with special-tips to contact all solder-joints fromboth sides of the package at the same time, remove part with tweezers when pad solder is liquid.

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12. PACKING & SHIPPING INFORMATION
Reel: 7” = 178 mm
Ø 13min. 12.4

max. 170,254 ±0,015+0,3

2 ±0,05

0,315 ±0,05

3028

3028

1,73 ±0,05

4 ±0,1

0,061

12 -0,1

5,5 ±0,05

3,43 ±0,05

4 ±0,1

1,75 ±0,1

Carrier Tape:
Material: Polycarbonate, conductive
Width: 12 mm
Tape Leader and Trailer: Minimum length 300 mm

0,83 ±0,05

Cover Tape

Direction of feed

All dimensions are in mm
RV-3028-C7_Tape-drw_20180208

Cover Tape:
Tape: Polypropylene, 3M™ Universal Cover Tape (UCT)
Adhesive Type: Pressure sensitive, Synthetic Polymer
Thickness: 0.061 mm
Peel Method:Medial section removal, both lateral stripes remain on carrier

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13. COMPLIANCE INFORMATION
Micro Crystal confirms that the standard product Real-Time Clock Module RV-3028-C7 is compliant with “EU RoHS
Directive” and “EU REACh Directives”.
Please find the actual Certificate of Conformance for Environmental Regulations on our website:
CoC_Environment_RV-Series.pdf

14. DOCUMENT REVISION HISTORY
Date

Revision #Revision Details

August 2018
August 2019

1.0
1.1

March 2021

1.2

September 2021

1.3

November 2021

1.4First release
Corrected typos and added sections
Corrected and added specifications and drawings
Added new disclaimer
Improved password description, 3.12., 3.15.3., 4.18.
Removed note about I2C interface re-initialization, 4.2.
Added "to any RTC register", 4.5., 4.5.1. and 4.5.2.
Corrected "VBAT" to "VBACKUP", 4.6.8.
Clarified text about I2C read/write data integrity and I2C re-initialization, 5.10.
Removed EEOffset calibrated Δt/t MAX value (±2 ppm), 6.3.
Removed older application circuit, 7.1.
Added four new application circuits, 7.1., 7.2., 7.3. and 7.4.
Adapted limit values and methods in accordance with the latest standards, 9.2.
Corrected package designation to SON-8 (DFN-8), 9.4.
Corrected text to "hot-air-gun set at temperatures >280°C.", 11.
Corrected location of designation "+ AMD1:2017", 9.2.

The information contained in this document is believed to be accurate and reliable. However, Micro Crystal
assumes no responsibility for any consequences resulting from the use of such information nor for any
infringement of patents or other rights of third parties, which may result from its use. In accordance with ourpolicy of continuous development and improvement, Micro Crystal reserves the right to modify
specifications mentioned in this publication without prior notice and as deemed necessary.
Any use of Products for the manufacture of arms is prohibited. Customer shall impose that same obligation
upon all third-party purchasers.
Without the express written approval of Micro Crystal, Products are not authorized for use as components
in safety and life supporting systems as well as in any implantable medical devices. The unauthorized useof Products in such systems / applications / equipment is solely at the risk of the customer and suchcustomer agrees to defend and hold Micro Crystal harmless from and against any and all claims, suits,
damages, cost, and expenses resulting from any unauthorized use of Products.
No licenses to patents or other intellectual property rights of Micro Crystal are granted in connection withthe sale of Micro Crystal products, neither expressly nor implicitly. In respect of the intended use of Micro
Crystal products by customer, customer is solely responsible for observing existing patents and otherintellectual property rights of third parties and for obtaining, as the case may be, the necessary licenses.

Micro Crystal AG
Muehlestrasse 14
CH-2540 Grenchen
Switzerland
November 2021

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Phone +41 32 655 82 82
sales@microcrystal.com
www.microcrystal.com

Rev. 1.4