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CLM920 TD3 LTE Module Hardware Usage Guide
3.3.3 VDD_SDIO 1.8V/2.85V Voltage output
Module output VDD_SDIO voltage is 2.85V/1.8V configurable, default is 2.85V,
maximum output current is 50mA, can only be used for SDIO bus pull-up, SD card power
supply needs to be provided from outside the module.
3.3.4 VDD_EXT 1V8 Voltage output
After the CLM920 TD3 module is powered on normally, the 17th pin will output 1.8V
and the current load will be 50mA. The external master can read the voltage of VDD_EXT to
judge whether the module is powered on. VDD_EXT can also be used as an external power
supply, such as a level shifting chip.
3.4 Switching machine reset mode
3.4.1 Boot
The 21 pin of the CLM920 TD3 module is the boot pin. The module is powered on at
low level. The PWRKEY is pulled low for at least 500ms. When the module is powered on,
the user can check whether the module is powered on by querying the high and low levels of
the VDD_EXT pin.
When the CLM920 TD3 module is powered on, pull the PWRKEY pin low for at least
1S and release it. The module will perform shutdown process shutdown (this function is under
development).
Pin
21
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Table 3-5 Switching machine pin definition
Signal name
I/O
PWRKEY
PI
High value
VBAT-0.3V
Description
Low level boot
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