Calibrating the VBAT internal potential divider on an STM32WLE5

[HWickham]

I am using the VBAT pin to measure the voltage of my battery, but the readings I am getting through this pin are always off by about 3%. The datasheet (https://www.st.com/resource/en/datasheet/stm32wle5cc.pdf#page=120) claims that there could be +-10% error on the ratio, this seems WAY too high to be at all useful so I was wondering if there was anyway to internal calibrate the resistors.

[TDK]

You would need to apply a known external reference voltage to VBAT and measure what you're getting to calculate the slope and calibrate.

This would need to be done on a per-part basis.

[HWickham]

This was my fear, thank you!

[waclawek.jan]

> This would need to be done on a per-part basis.

I also wouldn't hold my breath relying on temperature stability of the divider.

JW