EC25-EUX does not switch on when USB is connected

IoT Modules LTE Standard Module
1

I had got an EC25-EUX module (custom board from some unknown device) and I want to understand its status.
I connected directly to the USB pins (69 - 72), but after connecting to the computer the module does not start - VDD_EXT = 0V.
At the same time, a similar board with EC20 module switched on when powered by USB cable.

In Quectel_EC25_Series_Hardware_Design_V2.8 I did not found any explanation why the EC25 module does not switch on when connected by USB cable.

Please, can anyone suggest in which cases the module may not switch on?

2

Hi，
Please check if the power interface is correctly connected
And the notes in the reference manual.

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3

Pin USB_DP has a small resistance to GND.
The USB port on the module seems damaged.

I ordered a new module, we will see the results of its replacement.

4

Re-soldered the EC21 module and the board now works again.
Do not connect 5V from USB_VBUS and USB_DM :smiling_face_with_tear: