PWRKEY voltage is not stable

Technical Subjects Hardware Baseband
1

hi everybody

I have several EC200A which are not normal. at first PWRKEY voltage is 3.8V but after several minute voltage of PWRKEY goes low (randomly between 0.5V to 1.2V) and unstable so the module goes OFF and MCU cannot power on the module again. after this situation PWRKEY’s voltage periodically goes from 0.5V to 1.2V and this cycle repeat every 3 second. image below is waveform of PWRKEY in AC coupling.

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image1067×800 68.4 KB

2

Remove all external circuits of PWRKEY and RESET, and only provide power testing confirmation for the module,