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]

Ok, I read somehwere that the DC/DC basically activates on RF operation. And I disconnect the SWD after I flash it.