power measurement of system_off app on nRF54-DK

[bios-bob]

i've captured the following using a joulescope js-220 as an inline current meter across the VDDM CURRENT MEASURE jumper on my rRF54-DK board....

i'm running the system_off sample app, with the GRTC configured for a 2Hz wakeup....

per instructions in the docs, i don't have any open serial ports or attached debuggers....

now, take a look at the 85uJ consumed in the pink region -- consistent with an active system....

what i can't explain, however, is the 69uJ consumed in the green region -- which subsumes the pink region....

indeed, the blue region reports -8uJ over an interval when the system is off....

is there an explanation for what otherwise seems too good to be true ???

[Simonr]

I see, I thought you just mean 6µA there. If it's a negative number something is definitely off with the current measurement here. I'm not familiar with this joulescope, but how accurate is it supposed to be? You should also be able to supply the MCU using P6 as well as that's how we generally measure with using the PPK2 (using it as a source meter). Supplying the board from J3 will lead to a lot of leakages and other devices being powered as well.

The description of how you measure seems correct, but I guess it depends on how the board is powered in this case. There seems to be some leakage resulting in this negative current somewhere. 

Best regards,

Simon