Extra 5uA current draw

[davidz]

We are using nrfSDK1702. We have been trying to lower the current from a beacon. The beacon is active every 10s, then go back to sleep. The current consumption stays around 10.3uA after we tried different ways. According to the online power profiler for BLE, the current should be around 5.6uA. 

So our design consume almost extra 5 uA, which we want to get rid of. In our design, we did use the SAADC in low power mode to measure the battery level. SAADC resolution is 12bit. The battery level is only measured every 10s. 

The TWI bus is disabled in the main program by using "twi_unit" command (nothing connects to the TWI bus. 

Attached please find the sdk_config.h file.  Is there anything that can cause the extra 5uA? 75307.sdk_config.h

[Marte Myrvold]

Hi,

Some of our experts are out of office until Tuesday because of public holidays in Norway. We will come back to you next week.

Best regards,

Marte

[davidz]

Thanks Marte. We have found out the reason after lots of debugging. The extra 5uA is actually from the SAADC. Somehow nrf52840DK does not show the correct current draw when measured at VDD. When we measure at the custom board with a battery, then it shows the correct current draw. 

If we uninit the SAADC, then the current draw is down to 5.1uA in our custom board. This current draw matches the online profiler number very well.