Strange power consumptions on nrf9160DK with blinky sample

[harry4951]

Hi,

Hardware:

-nrf9160DK PCA10090 1.1.3

-PPK2

Software:

-ncs 2.6.1, blinky sample

-Power Profiler v4.0.0

Setup:

Both source meter mode and amprere meter way following the link below, external power supply is 5V:

 Getting started with current measurements on the nRF9160 

Issue:

I tested blinky sample on nrf9160DK with and without CONFIG_SERIAL=n, CONFIG_TFM_LOG_LEVEL_SILENCE=y, following this link: 

https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/test_and_optimize/optimizing/power_general.html

But the results is not the same as the above link and the power consumptions look strange.

Why one is in uA, one is in mA; one has roughly 700uA diff before and after optimization, one has 70uA?

Before optimization source meter mode:

Before optimization ampere meter mode:

After optimization source meter mode:

After optimization ampere meter mode:

Thanks

/CJ

[runsiv]

Hi Li

Have you prepared  the DK as mentioned here?

Regards

Runar

[harry4951]

Hi, yes. and strictly following the connection in two different modes with the link devzone.nordicsemi.com/.../getting-started-with-current-measurements-on-the-nrf9160

[runsiv]

Hi

I would recommend using another sample then Blink for measuring current with the 9160dk. There is a known issue when running applications that do not enable Modem library on nRF9160 with build code B1A, current consumption will stay at 3 mA when in sleep.Try to use for example the UDP sample as mentioned here "Navigate to the Cellular: UDP sample in nRF Connect SDK and copy the contents of the opp.conf file that you exported from Online Power Profiler into the prj.conf file in the UDP sample folder (samplescellularudp)." 
It might also be wise to use a fixed Y axis as the zoom level may cause confusion. 

Regards

Runar

[harry4951]

Thanks. I checked the nrf9160 on the DK, the build code is B1, does it apply to the same 3mA known issue?

How do you see the ampere meter mode measurement, why does it get 200uA ish, shouldnt it be the same 3mA ish as source meter mode?

[runsiv]

Thank you for your patience. The known issue is valid for the your device. I'm sorry but could you reword your last question?  The main difference between source mode or ampere mode is how the DUT(device under Test) is supplied. In Ampere mode it needs external power to drive the board while in source mode you can adjust the supply in the app 

Regards

Runart

[harry4951]

Hmmm, can you see the pictures in my original post? like the below. If you look at them carefully, you should see that in the scenario of ampere meter mode measurement, the average current is actually around 250uA, not 3mA. Why it differs with the the source mode scenario, in which case it is at 3mA level?
 

[runsiv]

Hi and thanks

I ran the plots over with a co-worker who have done more work on the 91dk. The source mode measurements looks correct and shows that the modem has the known current issue. However there is something strange with the amp measurement. How did you power the device? I would not be surprising  if the noise on the measurement comes from the USB if the device is powered by it, 

Regards

Runar