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.