EC20 shuts down after 20 seconds

I’ve got a custom board with an EC20EQAR02A13E2G that I’m evaluating before we update to the EC25.

The EC20 boots fine and I see NET_STATUS come up and the command and modem ports operate.

But only for 20-23 seconds. Then it shuts down and does not respond until I power cycle it.

I don’t see any activity on the PWRKEY or RESET_N pins.
There are no messages sent on the command or modem ports.

Any ideas on what is going on?

Dear Kena,
Thanks for your inquiry in Quectel forum.
About your issue, you can confirm whether the power supply is stable enough, you can use the instrument to monitor it. Thanks!

I checked with a multi-meter and the power supply is stable.

However I think that the voltage into the RESET_N and PWRKEY pins may be out of spec.

On my mini-pcie EC20 and EC25 dev boards I see 1.8v into the RESET_N and 80mv going into the PWRKEY.
I had thought that the EC20 has an internal pull-up resistor that brings the 600mv we are sending up to 1.8v.

Could this be the problem? Should we keep a steady 1.8v going into the RESET_N pin?

Many thanks,

Dear kena,
If you want to monitor the VBAT, it is recommend to use oscilloscope, not multi-meter. As you know that we need to check the whole power on process.
It is normal that RESET and PWRKEY is high level, it have pull-up internal. Thanks!


We did put an oscilloscope on the lines and they were steady. It turned out the issue was a mis-installed transistor that was sending only 600mv. Once that was fixed so PWRKEY was getting 1.8v the problem was resolved.

Thank you very much for your responses!

Ok, got it. Thanks for your updating.