Nordic PPK2 accuracy issue

[Thomas Krausee]

Hello,

I am using Nordic Power Profiler Kit II for measuring the consumption of a DUT (average 50mA + peaks) but the value returned is completely wrong.
I compare the value measured with an oscilloscope and a DMM. Both of them are coherent but not PPK2 which gives me a lower current each time. It seems to work with DC current but not accurate as soon as I have AC current. 
I checked with another PPK2 but result is exactly the same.
Is it a firmware problem ? Or shunt dead on the board?
Any idea is welcome.

Software and Firmware of the board : 

Thanks for your help

[Priyanka]

Hi Thomas,

Could you describe how you connected the PPK2 to your DUT?

I assume the DUT is a custom board?

Best Regards,

Priyanka

[Thomas Krausee]

Hi Priyanka,

Here is the setup : 

I confirm DUT is a custom board.

Regards,

Thomas

[Priyanka]

HI Thomas,

How is the VOUT from PPK2 connected to the DUT? What is it connected to? Are there any resistors?

Make sure that you follow the power supply specifications.

-Priyanka

[Thomas Krausee]

Hi Priyanka,

I am not sure to understand what is your point with power supply spec but VOUT replace Battery input so it is connected directly to a PMIC and a gas gauge.
Battery is 3.7V typical (4.2V max)

Thomas

[Priyanka]

Hi Thomas,

Sorry for the delay. The problem might be because the reference point might be 0, i.e. the current might be oscillating around 0. This is because the PPK2 cannot measure negative currents.

-Priyanka