ADC direct channel issue on STM32H7A3

[MNico.2]

Hello everyone,

I'm having some throuble in reading the direct analog input on channel PA0_C.

In my design I'm using several analog input. They seems to work properly in general and I have a precision more or less as expected. On channel PA0_C, though, I'm having a noise that is defenetly higher then the other channels (around 8-10x).

And I can't find the origin of this issue. I've get rid of the analog signal shorting the analog input to ground whit a 0 ohm resistor. The noise is still there and more or less the same (around 400points of adc, with a Vref=2.5V).

Going deeper with my investigation I've disconnecte the pin of the channel PA0 thet is not a direct channel, and closed the bypass switch that short PA0 and PA0_C. In this way I'm sure that the analog signal insede the chip is the same for both channels.

Even in this scenario the PA0_C channel gives worst results.

Does anyone experienced something like that?

[FBL]

Hello @MNico.2​ 

Here are some suggestions that might help:

1. Check for any noise sources that may be contributing to the issue, such as power supply noise (try using a different voltage reference or a different power supply), ground loops, or EMI.
2. Try to swap ADC fast channels to see if that makes a difference.
3. You can also try using a different voltage reference or a different power supply.