A7670x modem features
Here you will get a brief idea on what the device is capable of and the important features
The device has two power inputs,
This is the main power input of the device and is usually connected to the 12V DC adapter. Right now the device supports from 12VDC to 42VDC input . The main power chip used here is the TPS54240 switching regulator. which converts the 12VDC input to 4V which goes to modules VBAT pin.
This is the direct battery input and a 3.7V to 4.2V LiPo battery has to be connected to it. Use at least 400mAH battery. There is no reverse polarity protection to this pin so be careful connecting the battery. Use a battery with JST-XH size female connector.
To understand the power section of the device, look at the block diagram.