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]

I have tried to switch to nRF5_SDK_11.0.0-2.alpha_bc3f6a0 (I had a semi finished port to the alpha SDK 11 laying around)

And while it still is a semi dirty hack I have managed to get the softdevice up and running including advertisements.

But most importantly it now returns to ~ 1uA after a "NRF_POWER->SYSTEMOFF = POWER_SYSTEMOFF_SYSTEMOFF_Enter;" (While using the RC clock source for the LFCLK)

I strongly suspect that the non alpha version of the SDK/soft device also works as well.

[Visti Andresen]

Hi again Yaron

I can also confirm that nRF5_SDK_11.0.0_89a8197 is also capable of entering a OFF state with ~1uA while running the LFCLK from the RC source.

I therefor believe that the alpha softdevice S132 has a bug with regard to entering MODE_OFF and that the bug isn't present in the nRF5_SDK_11.0.0-2.alpha_bc3f6a0 nor the release version nRF5_SDK_11.0.0_89a8197

Hope this is helpful to you.

[yaron]

Hi Visti Thanks for your comments. I will test again with nRF5_SDK_11.0.0_89a8197 and update as soon as I can.

[Hauser]

Hey, any test results available? I made the same experience (shutdown current around 2.5mA) with s132_nrf52_1.0.0-3.alpha and nRF52_SDK_0.9.2_dbc28c9 and engineering B chip. On the PCA10036 (engineering A chip) the current is ok. Thx!

[Stefan Birnir Sverrisson]

If you have engineering B chip, you should use different softdevice and SDK version, see the nRF52 compatibility matrix.

[yaron]

Thanks Stefan. I will try your suggestion