Can I pull Vref- lower then Vss [stm32C5]

[DP_42]

Hello,

Is it possible to pull Vref- lower then Vss? For reverse voltage protrection I use a diode and a resistor to create GND1. GND1 is then connected to VSS of the µC.

Scematic. All caps omitted

Can I connect Vref- to GND? See Image.

Datasheet stm32c542cc

The datasheet does not specify.

If I connect Vref- to GND1 all values i measure with the ADC must be against GND1 otherwise the result is off by the offset of GND1 to GND.

[LCE]

Probably not.

The C562 datasheet makes it look like Vref- = GND:

 

[LCE]

BTW, make sure you connect VCAP, check the datasheet.

[TDK]

No. VSSA = VSS.

 

[DP_42]

2.1 of the application note 6274 is even more clear.

 

[Ozone]

In addition to the other mentioned points, look at the datasheet. Here an example for a F30x MCU :
 

The (-0.3V) is the average forward voltage of a shottky diode.