Extra current going through P21 in nRF52 DK

[runner]

Hi,

I'm doing power measurements for nRF52-DK (SOC nRf52832) and for nRF52840-DK. I'm able to measure reasonable figures from the external supply connector (P21) of nRF52840-DK after switching SW6 to "nRF only". But when I do the same with  nRF52-DK I get about 200uA higher figures compared to figures  I get  from P22 with shunt resistor connected to R6 pads. Is there any tricks to do to remove extra consumption with certain combination of solder bridge configuration etc. so I could use P21 only, OR do I always have to use P22 (as the guide says ;-)

Why I would like to use P21?

I'm using Qoitech's Otii Arc instruments' main power output port to supply power to the DK and the Arc's main port measures taken current more accurately than the ADC input does. So I'd rather use Arc to supply power to P21 since it measures the taken current internally in the Otii Arc.

I have tried to disconnect UART (SB22,23,24,25) and SWD (SB20,21) between interface MCU and the nRF52832, but still the extra current about 200uA is leaking somewhere.

Best Regards,

runner

[Bjørn Kvaale]

Hi Runner,

Our current expert will be back on Monday. I will share this case with him then if that works for you.

Kind Regards,

Bjorn

[runner]

Hi Bjorn.

Any news with this?  

Best Regards,

runner

[Bjørn Kvaale]

Sorry for the delayed response. Here is a case that should be helpful.

[runner]

Hi  Björn,

That was useful guide for the pca10040 but what SBs should I cut in pca10056 to measure nRF52840's current only?  As in pca10040 case I use the Otii device to supply power also for the pca10056 board. Since the Otii  measures the current taken from the it's supply current I need to connect it to P21 (or perhaps to P22 as in pca10040 case?) to measure current and get rid of any extra current drained by other components on the board. The user's guide for pca10056 did not explain this kind of set-up clearly, Please guide me what shall I do.

Thanks.

Ari