Smart Machine Smart Decision
SIM800C_Hardware_Design_V1.02 19 2015-4-27
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.
4.7K
47K
T u rn o n /o ff
impulse
PW RKEY
Power
o n /o ff logic
100K
3V
Module
1K
Figure 10: Powered on/down module using transistor
PW RKEY
Power
on/off logic
100K
3V
M odule
1K
Figure 11: Powered on/down module using button
The power on timing is illustrated as in the following figure.
V IL <0.7V
U ndefind
Active
VBAT
PW RKEY
(INPUT)
t> 3 s
VDD_EXT
STATUS
t> 1 s
Serial P o rt
T>1.5s
T>55m s
Figure 12: Timing of power on module
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