Turn Off Module By At Command; Automatic Shutdown - Quectel UC15 Hardware Design

During power-down procedure, module will send out URC "NORMAL POWER DOWN" via URC port first,
then log off network and save important data. After logging off, module sends out "POWERED DOWN"
and shuts down the internal power supply. The power on VBAT pins are not allowed to be switched off
before the URC "POWERED DOWN" is output to avoid data loss. If module is not logged off within 60s,
module will force to shut down internal power supply.
After that moment, the module enters into power down mode, no other AT commands can be executed.
The power down mode can also be indicated by the STATUS pin.

3.7.2.2. Turn off Module by AT Command

It is also a safe way to use AT command AT+QPOWD to turn off the module, which is similar to the way of
turning off the module via PWRKEY Pin. Please refer to document [1] for details about the AT command
of AT+QPOWD.

3.7.2.3. Automatic Shutdown

The module will constantly monitor the voltage applied on the VBAT_BB, if the voltage ≤ 3.5V, the
following URC will be presented:
+QIND: "vbatt",-1
If the voltage ≥ 4.21V, the following URC will be presented:
+QIND: "vbatt",1
The uncritical voltage is 3.3V to 4.3V, If the voltage > 4.35V or < 3.2V, the module would automatically
shut down itself.
UC15_Hardware_Design
Figure 11: Timing of Turning off Module
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UMTS/HSDPA Module Series
UC15 Hardware Design
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