nrf52 high current after sd_power_system_off

[yaron]

Hi I am trying to put the nrf52 device to system off state, in order to get minimal current consumption. When I don't use the soft device, and enter system off state by "NRF_POWER->SYSTEMOFF = 1", I see that CPU current goes down to a few uA. But when I enable the softdevice (using "SOFTDEVICE_HANDLER_INIT"), and than enter system off state by ""softdevice_handler_sd_disable" & "sd_power_system_off", I see CPU current of 5.83 mA!!!. If I add "NRF_POWER->SYSTEMOFF = 1" after "sd_power_system_off" , the CPU current goes down to 2.46 mA. I am currently using soft device version s132_nrf52_1.0.0-3.alpha. Is this a known issue with this version? If not, can some please explain? What is the correct way to enter system off state after soft device is enabled?

Thanks Yaron

[Visti Andresen]

Hi Yaron

I'm currently having a similar problem on my own board with a nRF52 revision QFAAB0 using nRF52_SDK_0.9.2_dbc28c9.

Are/was you by any chance calling SOFTDEVICE_HANDLER_INIT with a "NRF_CLOCK_LFCLKSRC_RC_250_PPM_500MS_CALIBRATION" option? I'm also getting around 2.5mA in system off using this.

If I use NRF_CLOCK_LFCLKSRC_XTAL_20_PPM the off current goes down to ~12uA (I don't actually have a 32Khz xtal on my board, so this isn't a practical solution for me)

Also if I don't call SOFTDEVICE_HANDLER_INIT at all I can get down to <=1uA as well

Currents was measured using a ET3255 meter

Kind Regards Visti