Smart Machine Smart Decision
SIM800_Hardware Design_V1.09
22
2016-06-30
power voltage drops below
3.4V, the module may be shut down automatically. The PCB traces from the VBAT
pins to the power supply must be wide enough (at least 80mil) 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.
VBAT
MIN:3.4V
Figure 9: The minimal VBAT voltage requirement at VBAT drop
Note: Hardware Power down voltage is 3.0V.
4.1.2.
Monitoring Power Supply
The AT command “AT+CBC” can be used to monitor the VBAT voltage. For details please refer to
document
[1].
4.2.
Power on/off SIM800
4.2.1.
Power on SIM800
User can power on SIM800 by pulling down the PWRKEY pin at least 1.2 second and then release. This pin is
already pulled up to VBAT in the module internal, so external pull up is not necessary. Reference circuit is shown
as below.
4.7K
47K
Turn on/off
impulse
PWRKEY
Power on/off
logic
100K
VBAT
Module
1K
Figure 10: Power on/off module using transistor
PWRKEY
Power on/off
logic
100K
VBAT
Module
1K
Figure 11: Power on/off module using button
The power on timing is illustrated as following figure.
Содержание SIMCom SIM800
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