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?

[MartinBL]

If you saw the same spikes in other projects I suppose you have done it correctly, but I'm going to ask anyway: does your probe attenuation match the settings on your scope? 13-14mA is suspiciously close to 10x of what you would expect from the refresh mode. The frequency seems a bit high for refresh in system off though, but the pulse width (10-15uS expected) seems to match too.