Monitoring Power Supply; Power On/Off Sim800C; Power On Sim800C - SimCom SIM800C Hardware Design

4.1.2.

Monitoring Power Supply

AT command "AT+CBC" can be used to monitor the VBAT voltage. For detail, please refer to document [1].

4.2. Power on/off SIM800C

4.2.1.

Power on SIM800C

Customer can power on SIM800C by pulling down the PWRKEY pin for at least 1 second and release. This pin
is already pulled up to VBAT in the module internal, so external pull up is not necessary. Reference circuits are
shown as below.
The power on timing is illustrated as in the following figure.
V B A T
P W R K E Y
(I N P U T )
V D D _E X T
S T A T U S
S eri al P ort
SIM800C_Hardware_Design_V1.02
P W R K E Y
4. 7K
T urn on/ of f
i m pul se
47K
Figure 10: Powered on/down module using transistor
P W R K E Y
Figure 11: Powered on/down module using button
T >1. 5s
V
T >55m s
Figure 12: Timing of power on module
3V
100K
P ow er
on/ of f l ogi c
1K
M odul e
3V
100K
P ow er
on/ of f l ogi c
1K
M odul e
t >1s
<0. 7V
I L
t >3s
U ndef i nd
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2015-4-27