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SIM800H&SIM800L_Hardware Design_V2.02 16
2015-07-27
3.2. Pin Description
Table 5: Pin description
Pin name
Pin number
I/O Description
Comment
Power supply
VBAT
1,42
I
Power supply
VRTC
56
I/O Power supply for RTC
It is recommended to
connect with a battery or a
capacitor (e.g. 4.7uF).
VDD_EXT
18
O
2.8V power output
If these pins are unused,
keep open.
GND
2,6,8,35,37,38,39,
41,43,44,45,58,67
,71,72,73,76,77,7
8,79,80,81,82,83,
84,85,86,87,88
Ground
GND for VBAT recommend
to use 2,43,44,45pin
Power on/down
PWRKEY
48
I
PWRKEY should
be pulled low at
least 1 second and then released to
power on/down the module.
Internally pulled up to
VBAT.
Audio interfaces
MIC1P
52
MIC1N
12
I
Differential audio input
SPK1P
53
SPK1N
13
O
Differential audio output
MIC2P
9
MIC2N
10
I
Differential audio input
SPK2P
51
SPK2N
11
O
Differential audio output
If these pins are unused,
keep open.
PCM interface
PCM_CLK
29
O
PCM_OUT
30
O
PCM_SYNC
65
O
PCM_IN
66
I
PCM
interface for digital audio
If these pins are unused,
keep open.
Keypads interface
KBC4
24
I
KBC3
21
I
KBC2
22
I
KBC1
25
I
KBC0
20
I
KBR4
63
O
KBR3
23
O
Support up to 50 buttons (5*5*2)
If these pins are unused,
keep open.（Please make
sure pin20 at high level
when power on）
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SIM800H&SIM800L_Hardware Design_V2.02 17
KBR2
61
O
KBR1
60
O
KBR0
62
O
GPIO
GPIO1
3
I/O
GPIO2
27
I/O
GPIO3
28
I/O
Programmable general purpose input
and output
NETLIGHT
64
O
Network status
STATUS
4
O
Power on status
Serial port
DTR
69
I
Data terminal ready
RI
68
O
Ring indicator
DCD
70
O
Data
carrier detect
CTS
34
O
Request to send
RTS
33
I
Clear to send
TXD
32
O
Transmit data
RXD
31
I
Receive data
If these pins are unused,
keep open.
Debug interface
VBUS
7
I
USB_DP
59
I/O
USB_DN
19
I/O
Debug and download
If these pins are unused,
keep open.
ADC
ADC
50
I
10bit general analog to digital
converter
If these pins are unused,
keep open.
PWM
PWM
26
O
Pulse-width modulation
If these pins are unused,
keep open.
I2C
SDA
75
I/O
Open drain output
SCL
74
O
Open drain output
If these pins are unused,
keep open.
SIM card interface
SIM_VDD
16
O
Voltage supply for SIM card.
Support 1.8V or 3V SIM card
SIM_DATA
14
I/O SIM data input/output
SIM_CLK
55
O
SIM clock
SIM_RST
15
O
SIM reset
All signals of SIM interface
should be protected against
ESD with a TVS diode
array.
SIM_DET
54
I
SIM card detection
If these pins are unused,
keep open.
Antenna interface
GSM_ANT
40
I/O Connect GSM antenna
BT_ANT
36
I/O Connect Bluetooth antenna
Only SIM800H
FM_ANTP
17
I
Differential antenna for FM
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4. Application Interface
4.1. Power Supply
The power supply range of SIM800H&SIM800L is from 3.4V to 4.4V.Recommended voltage is 4.0V.The
transmitting burst will cause voltage drop and the power supply must be able to provide sufficient current up to
2A. For the VBAT input, a bypass capacitor (low ESR) such as a 100 µF is strongly recommended.
Increase the 33pF and 10pF capacitors can effectively eliminate the high frequency interference. A
5.1V/500mW Zener diode is strongly recommended, the diode can prevent chip from damaging by the voltage
surge. These capacitors and Zener diode should be placed as close as possible to SIM800H&SIM800L VBAT
pins.
Figure 5: Reference circuit of the VBAT input
Table 6: Recommended zener diode
Vendor
Part number
Power(watts)
Packages
1
On semi
MMSZ5231BT1G
500mW
SOD123
2
Prisemi
PZ3D4V2H
500mW
SOD323
3
Vishay
MMSZ4689-V
500mW
SOD123
4
Crownpo
CDZ55C5V1SM
500mW
0805
The following figure is the reference design of +5V input power supply. The designed output for the power
supply is 4.1V, thus a linear regulator can be used.
Figure 6: Reference circuit of the LDO power supply
SIM800H&SIM800L_Hardware Design_V2.02 20
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If there is a high drop-out between the input and the desired output (VBAT), a DC-DC power supply will be
preferable because of its better efficiency especially with the 2A peak current in burst mode of the module. The
following figure is the reference circuit.
Figure 7: Reference circuit of the DC-DC power supply
The single 3.7V Li-ion cell battery can be connected to SIM800H&SIM800L VBAT pins directly. But the Ni-Cd
or Ni-MH battery must be used carefully, since their maximum voltage can rise over the absolute maximum
voltage of the module and damage it.
When battery is used, the total impedance between battery and VBAT pins should be less than 150mΩ.
The following figure shows the VBAT voltage drop at the maximum power transmit phase, and the test condition
is as following:
VBAT=4.0V,
A VBAT bypass capacitor C
A
=100µF tantalum capacitor (ESR=0.7Ω),
Another VBAT bypass capacitor C
B
=1µF.
Figure 8: VBAT voltage drop during transmit burst
4.1.1. Power Supply Pin
Pin 1 and Pin 42
are VBAT input, Pins 2,43,44,45 are GND of power supply, VRTC pin is power supply of the
RTC circuit in the module. VDD_EXT output 2.8V when module is in normal operation mode.
When designing the power supply in customer’s application, pay special attention to power losses. Ensure that
the input voltage never drops below 3.0V even when current consumption rises to 2A in the transmit burst. If the
power voltage drops below 3.0V, the module may be shut down automatically. The PCB traces from the VBAT
pins to the power supply must be wide enough (at least 60mil) to decrease voltage drops in the transmit burst.
The power IC and the bypass capacitor should be placed to the module as close as possible.