Battery voltage measurement via VDDHDIV5 reports incorrect values

RE: Battery voltage measurement via VDDHDIV5 reports incorrect values

abourdagept — Fri, 20 Feb 2026 16:00:08 GMT

I just stripped down our application to only the ADC battery voltage module with the intent of providing a minimal sample that reproduced the issue, and low and behold the issue disappeared on both the NRF21540DK and the NRF52840DK. There must be a devicetree conflict in our actual application that is causing the issue.

Since the hardware appears to behave as expected in a vacuum, the issue here must be on our end. I appreciate your time - I don't think any further action is needed here right now.

RE: Battery voltage measurement via VDDHDIV5 reports incorrect values

Hung Bui — Fri, 20 Feb 2026 13:27:09 GMT

Hi Alex,

Thanks for the reply. I will try to reproduce the issue here. I assume you can observe the same thing with a nRF52840 DK ? Otherwise I can try to get nRF21540DK to test.

RE: Battery voltage measurement via VDDHDIV5 reports incorrect values

abourdagept — Fri, 20 Feb 2026 12:50:03 GMT

Avoiding use of VDDHDIV5 in Normal Voltage mode makes sense, but I am reasonably confident that this isn't the issue I'm experiencing. I see the same symptoms if I start with VDDH = 3.6V or 3.8V, and a read of NRF_POWER_MAINREG_STATUS confirms that the chip is operating in High Voltage mode while sweeping from 3.6V to 4.0V and observing that measured voltage from the ADC in software is stuck at 3.0V.

RE: Battery voltage measurement via VDDHDIV5 reports incorrect values

Hung Bui — Fri, 20 Feb 2026 11:28:54 GMT

Hi Alex,
If you look at this tickets:
VDDHDIV5 with Normal Voltage Mode

SAADC VDDHDIV5 input on nRF52840 rev. 1

You can find similar observation.

I think the main issue here is that when you start the voltage at 3V the chip doesn't run in High Voltage mode hence the measurement on VDDHDIV5 may not be correct.

You could try the trick the customer suggested in the first link but as you can read in the ticket we don't guarantee that it works.