GSM/GPRS Module Series
M85 Hardware Design
M85_Hardware_Design Confidential / Released 28 / 88
1. Make sure that VBAT is stable before pulling down PWRKEY pin. The time of T
1
is recommended as
100ms.
2. EMERG_OFF should be floated when it is unused.
3. For more details about the application of STATUS pin, please refer to the
Chapter 3.15
.
3.4.2. Power Down
The following procedures can be used to turn off the module:
Normal power down procedure: Turn off module using the PWRKEY pin.
Normal power down procedure: Turn off module using command
AT+QPOWD
.
Over-voltage or under-voltage automatic shutdown: Take effect when over-voltage or under-voltage
is detected.
Emergent power down procedure: Turn off module using the EMERG_OFF pin.
3.4.2.1. Power Down Module Using the PWRKEY Pin
It is a safe way to turn off the module by driving the PWRKEY to a low level voltage for a certain time. The
power down scenario is illustrated as the following figure.
VBAT
PWRKEY
(INPUT)
STATUS
(OUTPUT)
EMERG_OFF
(INPUT)
Logout net about 2s to 12s
0.7s<Pulldown<1s
Figure 9: Turn-off timing
The power down procedure causes the module to log off from the network and allows the firmware to
save important data before completely disconnecting the power supply.
NOTES