GSM/GPRS Module Series
M66 Hardware Design
M66_Hardware_Design Confidential / Released 26 / 80
The turn-on timing is illustrated as the following figure.
VDD_EXT
(OUTPUT)
V
IL
<0.1*VBAT
V
IH
> 0.6*VBAT
VBAT
PWRKEY
(INPUT)
54ms
>1s
T
1
OFF
BOOTING
MODULE
STATUS
RUNNING
Figure 8: Turn-on Timing
Make sure that VBAT is stable before pulling down PWRKEY pin. The time of T
1
is recommended to be
100ms.
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
Under-voltage automatic shutdown: Take effect when under-voltage is detected.
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 below.
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