STM32G431RBT6 ADC internal Vref 2.048V

[sshan.2]

Hi Team,

We are using STM32G431RBT6, we have tested the ADC1 for PA3 i.e. Channel4 with external Vref 3.3 and VDDA 3.3 with 12-bit selection and the reading we are getting with 5 to 10 counts fluctuations we are seeing but when we have changed to internal voltage ref selection for 2.048 then the PA3 i.e. Channel4 is fluctuating more than 1000 counts! but it works fine for PA0!

VDDA remains same 3.3v for both our internal and external voltage.

Please suggest us how to resolve this?? 

Thanks 

[TDK]

The ADC is a multiplexer. Hardware downstream of the pin is the same for all channels, so this must be related to what's connected to the pin (or a misinterpretation). Show the hardware schematic and connection details and a plot of the data coming out if possible.