
CLM920_NC3_LTE Module hardware manual
Shanghai Yuge Information Technology co., LTD
- 28 -
It is recommended to add a large-capacity filter capacitor (10pF, 33pF, 100nF, 10uF,
220uF, etc.) to the VBAT pin to reduce voltage drop and reduce power supply ripple and
place it close to the VBAT pin.
The minimum operating voltage of the module is 3.3V. Since the transmission data or
GSM call will generate more than 2A current, the ripple voltage drop will occur on the
power supply voltage, so the actual supply voltage must not be lower than 3.3V.
3.3.3 VDD_SDIO 1.8V/2.85V Voltage output
The module output VDD_SDIO is configurable at 2.85V/1.8V. The default is 2.85V and
the maximum output current is 50mA. It can only be used for SDIO bus pull-up. The SD card
power supply needs to be provided from outside the module.
3.3.4 VDD_EXT 1V8 Voltage output
After the CLM920 NC3 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 NC3 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 NC3 module is powered on, pull the PWRKEY pin low for at least
1S and release it. The module will perform shutdown process shutdown.
Table 3-5 Switching machine pin definition
Pin
Signal name
I/O
High value
Description
21
PWRKEY
PI
VBAT-0.3V
Low level boot