CA0022AN
WATCHDOG TIMER and RESET IC■Device description
CA0022AN is watchdog timer reset IC.
It delivers a low current consumption and a small package. It can be used in a microcomputer to monitor power supply
voltage and in system operation to prevent runaway operation.

■Functions and features
⚫
⚫
⚫
⚫
⚫
⚫
⚫
⚫

Low current consumption: 14μA(Typ.)Operating temperature range: -40ºC～+85ºC(Automotive)
Comparator with hysteresis
RESET delay time can be set with the CT pin’s external capacitance.
Watchdog timer monitor time and reset time can be set with CTW pin’s external capacitance.
Watchdog timer operation can be set with the INH pin.
Output type: N-channel open drain (RESET pin)
Package: small, thin, bottom mounting(Plating Lead Package: 2.2mm×2.2mm×t:0.58mm 8pin)■ABSOLUTE MAXIMUM RATINGS
Item

SymbolRatings

Unit

Power supply voltage

VDD-0.3～6.0

V

CT pin voltage

VCT-0.3～VDD+0.3

V

CTW pin voltage

VCTW-0.3～VDD+0.3

V

RESET pin voltage

VRESET-0.3～6.0

V

CLK pin voltage

VCLK-0.3～VDD+0.3

VINH pin voltage

VINH-0.3～VDD+0.3

V

Power dissipation

Pd90mW

Operating ambient temperature

Ta-40～+85ºC

Junction temperature

Tj-40～+125ºC

Storage temperature

Tstg-40～+125ºC■RECOMMENDED OPERATING RANGES（Ta = -40℃～+85℃）

DS0324-3E

Item

SymbolRatings

Unit

Power supply voltage

VDD

1.5～6.0V

2020/11/18

1WATCHDOG TIMER and RESET IC■BLOCK DIAGRAM

VDD

VDD

VDD

58RESET

4GND

3

CLK+VrefCT

2WDT RESET DETECTIONVDD RESET RELEASERESETControl

VDDCTW

1DS0324-3E

WDTControl

2020/11/1867INH

N.C.

2

WATCHDOG TIMER and RESET IC■ELECTRICAL CHARACTERISTICS
Unless otherwise specified, Ta = -40ºC～+85ºC, VDD=3.3V. TYP values are at Ta = +25ºC. *1
Item

SymbolCondition

MIN

TYP

MAX

Unit

Consumption current

IDD

During WDT operation

-14.0

20.0

μA

Ta=25ºC

2.765

2.875

2.985

Detection voltage

VDET-40ºC ≤ Ta ≤ +85ºC

2.740

2.875

3.010

Ta=25ºC

130

145

160mV-40ºC ≤ Ta ≤ +85ºC

125145165mV

Hysteresis width

VVhys

RESET output current

IOL

VDD=1.5V, VDS=0.5V

0.7

2.0-mARESET output leak current

IOH

VDD=3.3V, VDS=3.3V-

0.0

1.0uA

RESET delay time *2

TPLH

L→H
CT=0.001μF

3.9

6.9

10.1msDelay pin circuit resistance

RRST

VCT=GND

5.8

10.0

14.5

MΩ

Delay pin threshold voltage

VCTH-

Delay pin output current

ICT

VDD=1.5V,VCT=0.5V

150

330-uA

Minimum operating supply
voltage

VOPL

VDS=0.3V,
Rpull-up=10kΩ

--

1.5

V

WDT monitor time *3TWH

CCTW=0.01μF

7.011.1

20.0ms

WDT reset time *4

TWL

CCTW=0.01μF

2.4

3.7

7.0ms

CLK input pulse width

TWCLK-500--ns

CLK high level voltage

VCLKH-

VDD×0.8-

VDDV

CLK low level voltage

VCLKL-0-

VDD×0.3

V

INH high level voltage

VINHH

-

VDD×0.8-

VDD

V

INH low level voltage

VINHL

-0-

VDD×0.3

V

CTW charge current

ICTWC

VCTW=0.15V

0.25

0.45

0.75

uA

CTW discharge current

ICTWO

VCTW=0.85V

0.75

1.35

2.00

uA

VDD×0.3 VDD×0.5 VDD×0.6*1 High and low temperature limits are guaranteed by design, production testing performed at +25ºC only.
*2 TPLH can be varied by the CT pin capacitance value.
TPLH(s) ≒ 0.69 × RRST(MΩ) × CCT(μF)*3 TWH can be varied by the CTW pin capacitance value.
TWH(s) ≒ 0.5 × CCTW(μF) / ICTWC(μA)*4 TWL can be varied by the CTW pin capacitance value.
TWL(s) ≒ 0.5 × CCTW(μF) / ICTWO(μA)
DS0324-3E

2020/11/18

3V

WATCHDOG TIMER and RESET IC■MEASUREMENT CIRCUIT DIAGRAM

1CTW

RESET

810kΩ

0.01μF

2CT

N.C.

73

CLK

INH

64GND

VDD

51CTW

RESET

82CT

N.C.

73

CLK

INH

64GND

VDD

510kΩ

0.01μF0.001μF

0.001μF

VA
VDD

3.3V

3.3V

Detection voltage ／ Hysteresis width

Consumption current

1CTW

RESET

3.3V

80.01μF

1CTW

RESET

82CT

N.C.

73

CLK

INH

64GND

VDD

50.01μF

2CT

N.C.

70.001μF

0.001μF

3

CLK

INH

64GND

VDD

5A
1.5V

A
0.5V

3.3V

RESET output current

1CTWRESETRESET output leak current

810kΩ

0.01μF

2CT

N.C.

73

CLKINH

64GND

VDD

53.3V

1CTW

RESET

82CT

N.C.

73

CLK

INH

64GND

VDD

510kΩ

0.01μF0.001μF
OSC Oscilloscope

A
3.3V

3.3V

Pulse generator

Delay pin circuit resistance

RESET delay time

1CTW

RESET

3.3V

810kΩ

0.01μF

2CT

N.C.

73

CLK

INH

64

GND

VDD

51CTW

RESET

82CT

N.C.

73

CLK

INH

64GND

VDD

510kΩ

0.01μF

VA
VCTH

3.3V

3.3V

0.5VDelay pin threshold voltage

DS0324-3E

2020/11/18

1.5V

Delay pin output current

43.3V

WATCHDOG TIMER and RESET IC

1CTW

RESET

810kΩ

0.01μF

2CT

N.C.

73

CLK

INH

64GND

VDD

51CTW

RESET

82CT

N.C.

73

CLK

INH

64GND

VDD

510kΩ

0.01μF0.001μF

0.001μF

V

VDD

3.3V

1CTW

RESET

810kΩ

2CT

N.C.

73

CLK

INH

63.3V

WDT monitor time ／ WDT reset time

Minimum operating supply voltage

0.01μFOSC Oscilloscope

1CTW

RESET

82CT

N.C.

73

CLKINH

610kΩ

0.01μF0.001μF

0.001μF
OSC Oscilloscope

Pulse
generator

OSC Oscilloscope

Pulse
generator

4GND

VDD

543.3V

CTW

RESET

VDD

53.3V

3.3V

CLK input pulse width ／ CLK high level voltage ／ CLK low level voltage

1

GND

INH high level voltage ／ INH low level voltage

81CTW

RESET

82CT

N.C.

73

CLK

INH

64

GND

VDD

510kΩ

2CT

N.C.

73

CLK

INH

64GND

VDD

53.3V

10kΩ

0.001μF

0.001μF

AA
0.15V

3.3V

3.3V

0.85VCTW charge current

DS0324-3E

2020/11/18

3.3V

CTW discharge current

53.3V

WATCHDOG TIMER and RESET IC■TERMINAL FUNCTIONSPin No.

SymbolTerminal function

1

CTW

WDT time setting capacitor
connection terminal

2

CT

RESET delay time setting capacitor
connection terminal

3

CLK

Clock input terminal(Rising edge detection)

4

GND

Ground terminal

5

VDD

Power supply terminal

6

INH

WDT on/off terminal(INH=H/L : WDT=off/on)

7

N.C.

Non connection terminal

8

RESET

RESET output terminal(N-channel open drain)Top view
876

Bottom view
51234876

51pinマーク

1234

Open the electric potential of the die pad on the back side of the package or connect the die pad to the GND.
When the die pad is connected to the GND, do not use the die pad as the electrode unless shorting with 4 pin.

DS0324-3E

2020/11/18

6

WATCHDOG TIMER and RESET IC■BASIC CIRCUIT EXAMPLE

Power Supply

CA0022AN

Rpull-up = 10kΩ
VDD

1CTW

RESET

82

CT

N.C.

7RESET

CCTW = 0.1μF

Microcomputer

CCT = 0.022μF
3

CLKINH

64GNDVDD

5Inhibit Data

CLKGND

Cd ecou pling = 0.1μF※Connection and constant of CT pin external capacitor and CTW pin external capacitor and RESET pin external resistor
and Decoupling capacitor in the above figure does not guarantee the operation. Please select the constant perform enoughevaluation including the temperature characteristics.
Capacitance recommended value is as follows.
CT pin external capacitor: CCT = 470pF to 3.3μF
CTW pin external capacitor: CCTW = 0.001μF to 10μF

DS0324-3E

2020/11/187

WATCHDOG TIMER and RESET IC■TIMING CHART

VDD

VDET+VHYSVDET0VCTHVCT0

INH="H" (WDT: OFF)
INH
INH="L" (WDT: ON)

0

TWCLK

CLK0VthH

VCTW

VthL
0TWL TWHTPLH
RESET0① ② ③④DS0324-3E

2020/11/18⑤⑥⑦8⑧⑨⑩

WATCHDOG TIMER and RESET IC■OPERATION EXPLANATION①．The RESET pin voltage switches to low voltage when the power supply voltage VDD rises to about 0.8V.
②．The external capacitor connected to the CT pin begins to charge when VDD rises above the reset release voltage
VDET+VHYS.
③．The RESET switches to high voltage (release) from low voltage (detection) when the CT pin voltage VCT reaches thedelay pin threshold voltage VCTH. RESET delay time TPLH is given by the following equation:
TPLH(s) ≒ 0.69 × RRST(MΩ) × CCT(μF)
RRST(MΩ) denotes the IC's built-in resistance and is designed to be 10MΩ(Typ.). CCT(μF) denotes the external capacitor
connected to the CT pin and can be set optionally.
④．The external capacitor connected to the CTW pin begins to charge when the RESET switches to release fromdetection, the watchdog timer operates.
⑤．The CTW pin state switches from charge to discharge when the CTW pin voltage VCTW reaches the V thH, theRESET switches to low voltage from high voltage. The watchdog timer monitor time TWH is given by the following
equation:
TWH(s) ≒ 0.5 × CCTW(μF) / ICTWC(μA)
ICTWC(μA) denotes CTW charge current and is designed to be 0.45μA(Typ.). CCTW(μF) denotes the external capacitor
connected to the CTW pin and can be set optionally.
⑥．The CTW pin state switches from discharge to charge when the CTW pin voltage VCTW reaches the VthL, the RESETswitches to high voltage from low voltage. The watchdog timer reset time TWL is given by the following equation:
TWL(s) ≒ 0.5 × CCTW(μF) / ICTWO(μA)
ICTWO(μA) denotes CTW discharge current and is designed to be 1.35μA(Typ.). CCTW(μF) denotes the external capacitor
connected to the CTW pin and can be set optionally.
⑦．When a pulse is input to the CLK pin while the CTW pin is charging, the CTW pin state switches from charge todischarge. Once the CTW pin discharge and VCTW reaches VthL, the CTW pin will charge again. The CLK pin pick up
only the rising edge. Pick up operation is unaffected by duty of a pulse. The CTW pin state does not switch to discharge
while VCTW is VthL or below, if a pulse is input to CLK.
⑧．When the INH pin switches to high, watchdog timer operation is forced off by discharging forcibly the CTW pinstate. Only watchdog timer function is turned off, and detection function for power supply voltage is performed normally.
While the INH pin is high, these functions stay are performed.
⑨．RESET switches to low from high when VDD falls below the reset detection voltage VDET.
⑩．RESET signal stays low until VDD falls about 0.8V.

※WDT monitor time
Only first WDT monitor time after reset release by rising voltage, and first WDT monitor time after watchdog timer
switches to ON from OFF by input to the INH pin, is given by the following equation:
TWH1(s) ≒ 0.75 × CCTW(μF) / ICTWC(μA)
When capacitance of CTW pin external capacitor is used bigger, the capacitor takes longer to discharge by INH function.
Note that the WDT monitor time may be shorter than the above equation when the capacitor is not discharged enough.
※CLK pin and INH pin
CLK pin and INH pin should not left open because of connecting CMOS gates. These pins should be either pulled up ordown.

DS0324-3E

2020/11/18

9

WATCHDOG TIMER and RESET IC■CHARACTERISTIC DATA(REFERENCE)

Consumption Current vs. Temperature

Consumption Current vs. Supply Voltage

2025

161412108-40-20

020406080100Comsumption current: I DD [μA]

Comsumption current: I DD [μA]

Ta=105℃
18

Ta=85℃

2015

Ta=25℃
10

Ta=-40℃

5001Ambient temperature: Ta [℃]

45680

100

Hysteresis Width

3.15

175

3.10

Hysteresis width: V hys [mV]

Detect voltage: V DET [V]

3Supply voltage: VDD [V]

Detection Voltage
VDET+Vhys

3.05
3.00
2.95
2.90
2.85

VDET

2.80
2.75
-40-20020

4060

80

165
155
145
135
125
115

100-40-20

Ambient temperature: Ta [℃]

55RESET voltage: V RESET [V]

6Rpull-up =10kΩRpull-up =470kΩ

3204060RESET Output Voltage vs. Temperature(Rpull-up=10kΩ)

640Ambient tenperature: Ta [℃]

RESET Output Voltage vs. Supply Voltage(Ta=25ºC)
RESET voltage: V RESET [V]2210

Ta=-40℃
Ta=25℃

Ta=85℃
4Ta=105℃

32100123456

Supply voltage :VDD [V]DS0324-3E

2020/11/18

01234

Supply voltage :VDD [V]1056

WATCHDOG TIMER and RESET IC■CHARACTERISTIC DATA(REFERENCE)RESET Output Current vs. Temperature

RESET Output Current vs. VDS(VDD=1.5V)
4.0

2.5

2.0

1.5

1.0

Ta=-40℃
Ta=25℃

Output current: IOL [mA]

Output current: I OL [mA]

3.0

3.0

2.0

Ta=85℃
Ta=105℃

1.0

0.0

0.5
-40-200204060

800100

12RESET Delay Time vs. Temperature

56100000

987654-40-20020406080100

Output delay time: T PLH [ms]Output delay time: T PLH [ms]4RESET Delay Time vs. Capacitance

1010000

1000

1001010.0001

0.001

Ambient temperature: Ta [℃]

0.01

0.1

110CT PIN capacity: CCT [μF]

Delay Pin Circuit ResistanceDelay Pin Threshold Voltage

140.7121086-40DS0324-3E-20020406080100

Ambient temperature: Ta [℃]2020/11/18

Output delay threshold: V CTH [V]Output delay resistance: R RST [MΩ]

3Output voltage: V RESET [V]Ambient temperature: Ta [℃]

0.60.50.4

0.3

0.2-40-200204060

Ambient temperature: Ta [℃]1180100

WATCHDOG TIMER and RESET IC■CHARACTERISTIC DATA(REFERENCE)

Delay Pin Output Current vs. Supply Voltage(VDS=0.5V)

Delay Pin Output Current vs. Temperature

500

450

400

Ta=85℃
300

Ta=25℃
Ta=-40℃

200

100001234Output delay current: I CT [μA]

Output delay current: I CT [μA]

Ta=105℃
400
350
300
250
200
150-40

Supply voltage: VDD [V]20406080

100

WDT Time vs. capacitance

15.0

10000

12.0

WDT time: T WH, T WL [ms]WDT time: T WH, T WL [ms]0Ambient temperature: Ta [℃]

WDT Time vs. Temperature

T WH

9.06.0

3.0T WL
0.0-40-20020406080

1000

TWH100T WL1010.10.0001

1000.0010.010.1

110

CTW PIN capacity: CCTW [μF]

Ambient temperature: Ta [℃]

CTW Current vs. Temperature

CTW Current vs. CTW Voltage
2.00

CTW current: I CTWC, I CTWO [μA]2.0

CTW current: I CTWC, ICTWO [μA]

-20

1.5

ICTWO
1.00.5

ICTWC
0.0-40-20

020

4060

80

100

Ambient tempreature: Ta [℃]

DS0324-3E

2020/11/18

1.50
1.00

Ta=105℃
Ta=85℃

0.50

Ta=25℃

0.00

Ta=-40℃
-0.50
-1.00
012

CTW voltage: V CTW [V]123WATCHDOG TIMER and RESET IC■EQUIVALENT CIRCUIT OF INPUT AND OUTPUT TERMINAL

SymbolEquivalent circuit

VDD

GND
VDD

VDD

10MΩ(Typ)

CTCT

VDD

VDD

CTWCTW

VDD

CLK

CLK

VDD

INH

INH

RESET

RESET

DS0324-3E

2020/11/18

13WATCHDOG TIMER and RESET IC■EXTERNAL DIMENSIONS

単位：[mm]Unit

2.20⑧⑦⑥⑤2.20

1pinマーク②③④
0.6 MAX

①0.30

1.00

0.30

0.10

0.5

DS0324-3E

2020/11/18

0.30

1.80

0.20

14WATCHDOG TIMER and RESET IC

Note for customers
If any product described in this document corresponds to goods or technologies which are restricted to export under
the Japanese “Foreign Exchange and Foreign Trade Control Law” or other applicable laws of a government having
jurisdiction, then, appropriate permission for exporting such products or technologies are required to be taken.
In relation to use of the information contained in this document, no license is granted to you with regard toany
intellectual property rights of YITOA MICRO TECHNOLOGY CORPORATION (hereinafterreferred to as "MTC")
or any third party. MTC will not be liable in any way for any claim related to infringement of intellectual property
rights or other rights of third parties arising from the use of theinformation contained in this document.
The information concerning the circuits and other related information contained in this document is provided forreferential purpose only to explain the operation or application of the products, and it will be your sole responsibility
to use such information for designing of your own devices. MTC will not be liablein any way for any loss or damages
incurred to you or any other party arising from the use of such information.
In general, failures in semiconductor products occur at certain percentage. Therefore, upon designing your own
devices, please give due consideration to the redundancy, safety of your devices and methods to prevent occurrence ofmalfunction in order to avoid personal injuries, accidents or other social damages which might happen as the result ofa failure of semiconductor products used in your devices.
For application of MTC products to medical equipment or other purposes where high reliability of the device isrequired, please contact MTC sales representative.
The contents of this document may be subject to change without any notice, due to improvement of reliability or
design of the products.
It is inhibited to reproduce or copy the whole or part of this document without the permission of MTC.

Address ：465 Osato-cho, Kofu-shi, Yamanashi-ken, 400-0053, Japan
TEL ： +81-55-241-8622
FAX ： +81-55-241-8769

DS0324-3E

2020/11/18

15