NRF52 current peaks

[genis]

I am seeing strange current spikes when measuring the consumption in a nRF52 chip. The board the chip is on is a custom board, but the nRF52 power supply has been isolated so its consumption can be measured alone. I didn't flash any soft device and I'm running the simplest of the programs to enter System OFF mode.

int main(void) {
    NRF_POWER->DCDCEN |= POWER_DCDCEN_DCDCEN_Msk;
    NRF_POWER->TASKS_LOWPWR = 1;
    NRF_POWER->SYSTEMOFF = POWER_SYSTEMOFF_SYSTEMOFF_Enter;
}

Still, I see spikes of current at about 3.5Hz with max current peaks of about 13-14mA. See images below (sorry about the narrow yellow spikes):

The only explanation I can think about is that it may be caused by the refresh modes of the current regulator, as explained in some other posts in this forum. Anyway that's a very unclear feature to me and I can't find anything about it on the nRF52 product spec. Also those peaks I'm measuring are really high and very often.

Anyone any thoughts about this?

[genis]

Thank you for your help. That's the only code in my project apart from the startup code, which I got from one of the examples in the SDK. The chip is powered at 3V and supply is stable and no reset is occurring.

I saw the same spikes while monitoring the consumption in a larger project. I started to remove code modules to try to identify what was causing the current spikes and ended up with the snippet I pasted no the question. In the original, larger project I could see the same kind of spikes although at a different rate.

The behavior I see is very similar to the "power off" graph in this tutorial: devzone.nordicsemi.com/.../. The biggest difference is that my current spikes are way larger than those in the tutorial. I wonder if I could reduce them somehow as it's drawing a lot of power from the battery right now.