STM32 WLE5 VBat measurement at low temperatures

[HWickham]

Hi,

I am currently doing some tests measuring the battery voltage on a system using the STM32WLE5, I am measuring both v_sys and v_bat. I am running into an issue with the v_bat measurement, I am seeing alot of noise compared to the v_sys measurement. I am using a bench supply currently to prevent any fluctuations due to the supply. I have attached an image below of the plot of voltage against time, and then below that is voltage against temperature (the same data points)

[Louis AUDOLY]

Hello @HWickham​ ,

First thank you for your question !

In fact v_bat is connected to a switch that power or not the backup domain in case you have an issue with your VDD. So this pin need to be plugged on stable power source, but not stayed unconnected.

This could explain this behavior !

Regards