VDDH measurement with the ADC (nrf52840 QIAAC0)

[Abderrezak Mekkaoui]

Dear All,

I am measuring VDD and VDDH using the internal SAADC. In normal mode (VDDH not connected to VDD) the reported results are good (3.0V and 1.8V for example). But in high voltage mode (VDDH connected to VDD), the VDD measurement is correct but not that of VDDH (1.9V and 3V) instead of (3V and 3V). Same results with 3 boards from 3 different vendors. Is this behavior normal?

Thanks

[haakonsh]

In normal mode (VDDH not connected to VDD) the reported results are good (3.0V and 1.8V for example).

 What do you mean by "VDDH not connected to VDD", that REG0 is not used?
 

But in high voltage mode (VDDH connected to VDD), the VDD measurement is correct but not that of VDDH (1.9V and 3V) instead of (3V and 3V).

 Can you show us a schematic of the two modes you are referring to, and tell us when you are using REG0?