Chip consumes 6mA in system off

[quadrotis]

I have 2 custom made boards.

I took the first board.

I tested low power consumption. And it WAS working.

Made multiple tests on i2c, BLE, GPIO, Flash memory... All worked fine.

Then i got back to test low power again and low current consumption stoped to work. Even in system off mode power consumption is 6mA.

All other features still working fine.

Then i've repeated the same steps for the second board. And got the same results. Low power consumption was working and then, after several tests, it stoped. 

During mesurement the board is disconnected from computer and conected to powersupply trough my multimiter.

Here is my code:

int main()
{
NRF_POWER->SYSTEMOFF=1;
while(true)
{
  __WFE();
  __SEV();
  __WFE();
}
}

Also i have softdevice installed.

I've tryed to erase entire chip and reprogram it. No success.

Have no idea what to do next. Please help!

[Stian Røed Hafskjold]

Can you please post the schematics for a review. Thanks

[quadrotis]

Sorry, i don't have schematics.

But it seems like i've found the problem after i broke my 3-rd board.

For those who will face the same problem:

The problem was in my power supply. When i switch it of - it generates high voltage spike.

This spikes, seems to be, damaging the chip only a bit. So it continues to work but without ability to go to system off.

After several On/Off cycles chip starts to consume over 100 mA and stops responding.

[Stian Røed Hafskjold]

Ahh ok, I see. That's not good.  Glad you figured it out though. Can I ask what type of power supply you are using?

[quadrotis]

It's KORAD KD3005D