EC25 VDD_EXT output

In our first enginnering samples, the EC25 module does not output the 1.8V from VDD_EXT (pin 7) after 3.9V power suppled to VBAT pins.

Does anyone know the cause of this problem ?

W.K. Tam

Is PWRKEY pulled down to perform startup? If VDD_EXT does not output, the module will definitely not boot up properly.
If you execute PWRKEY to pull it down, and there is no output from VDD_EXT, it is recommended to use an oscilloscope to measure the waveform and see if there is any change in VDD_EXT.
It is also possible to measure the diode characteristics of the VDD_EXT pin to determine if the pin is damaged.

Thanks. After execute the PWRKEY pulling down, it works.

We are facing another problem. We cannot detect sim card. We got error SIM not inserted.

I checked the electronic circuit. The connection is right.

Does any expert know the cause of this problem ? How to fix it ?

Thanks.

You use AT+CFUN=0, then AT+CFUN=1. After executing the AT command, use an oscilloscope or multimeter to measure whether there is voltage output at each pin of the SIM card. If there is no voltage on any pin, the module is abnormal.
Please note that the output power time of each pin will be very short. Only when the communication between the module and SIM card is completely normal, can all pin signals be continuously output.
If there is voltage, it indicates that the card is abnormal or the connection between the card and the module is abnormal.