User's Manual

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