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UMTS/HSPA Module Series

UC20 Hardware Design

UC20_Hardware_Design Confidential / Released 33 / 82

VBAT

PWRKEY

Log off network about 1s to 60s

≥ 0.6s

RUNNING

Power-down procedure

OFF

Module

Status

STATUS

(OD)

Figure 12: Timing of Turning off Module

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 shut down the internal power supply. The power on VBAT pins is not allowed to turn off before the

URC “POWERED DOWN” is output to avoid data loss. If logging off is not done within 60s, module will

shut down internal power supply forcibly.

After that moment, the module enters the power down mode, no other AT commands can be executed

and only the RTC is still active.

3.7.2.2. Turn off Module Using AT Command

It is also a safe way to use AT command AT+QPOWD to turn off the module, which is similar to 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, 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

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