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

[davidz]

Here is some additional information: The measurement is from VDDH, not VDD on our custom board. If we measure the current from VDD (connector p22) at nrf52840 DK, then it shows the correct current draw (around 5.1uA). In our custom board, the voltage is supplied to VDDH. We don't have an easy way to measure the current from VDD to the rest of circuit in the custom board. 

We use the default LDO inside nrf52840 on the custom board. Could the LDO has the leak current of 5uA? 

BTW, we measured VDD at the custom board and it shows 3.0v. VDDH is at 3.8v. We did not set the voltage register for VDD. VDD should have a default output of 1.8V. Why VDD is 3.0V instead?