NRF9151 DK Supply Current Measurement

[tc531]

We're trying to measure supply current used by the NRF9151 DK but have discovered that the current measurment connector (P22) only includes current supplied to VDD, and that VDD_GPIO isn't measured since it comes from the nPM1300 (U9) which is supplied direct from 5V.  U9 also supplies power to U3A, the debugger, which is not present on our target.  

Is there a way measure the total supply current into the NRF9151, to simulate our target, without including the debugger?

Kind regards

Tim

[Kazi Afroza Sultana]

Hello Tim,

To the best of my knowledge, P22 measures only the current of VDD_nRF and not VDD_GPIO. However, I have been investigating potential methods to implement such a measurement on a custom board. I will come back to you soon.

Thanks.

BR

Kazi

[Stian Røed Hafskjold]

Hello,

You need to isolate the VDD_GPIO domain from the rest of the DK, and measure the current going into this domain.

You can cut SB31, to isolate VDD_GPIO, then power directly on VDD_GPIO on P20 with an SMU or similar. Note that the voltage needs to match the VDD voltage on the DK, which is 1.8V. 

If you want to measure at a higher voltage you need to cut SB33 as well, and supply VDD on P20 separately (so that you don't include this current in your measurements), with the same voltage as VDD_GPIO. Note that the VDD_GPIO allowed voltage ranges are different than for VDD_nRF

The USB should always be plugged in to power the remaining components on the DK.

Best regards,
Stian

[tc531]

Thanks for the advice both.  I'll not be able to verify it because I don't want to carve up our 9151 DK - the SB's you refer to are very small.  We also don't have a SMU (Source Measure Unit) other than the PPK2 (a very useful device) but that's committed to measuring VDD-nRF.