Effect of varying supply voltage on SAADC

[KellyJust]

I have a custom board with the NRF52832 chip. The supply is from a Lipo battery which after 3.6v varies from 3.6v to 2.5v. hence I have a varying input supply to NRF. Would this have any effect on the 0.6v reference voltage for SAADC or even the raw analog reading from 0 -1023. Also is there any other change that I should expect with the changing voltage, one would be the current being drawn, anything else to keep in mind?

TIA.

[Jørgen Holmefjord]

Hi,

The internal reference is regulated at 0.6V and should not be affected by varying supply voltage. The internal reference accuracy is built into the Gain error parameter, as mentioned in this post.

Unless you are measuring the VDD voltage, or use VDD/4 as reference, the samples should be affected by the variation in the supply voltage. You should not have to take any extra care as long as the analog input is between GND and VDD at any time.

Best regards,
Jørgen