STM32 internal reference voltage configuration

[abhijith_raj]

Hi,
I am working with STM32G491RET6 and currently implementing the ADC. I have a question regarding the ADC reference voltage.

If the external 3.3 V supply is removed from the VREF+ pin and VREFBUF is disabled, does the ADC operate using any internal reference voltage, or will the ADC readings be invalid?

Could someone clarify how the ADC reference behaves in this case?

 

[waclawek.jan]

ADC reference *is* the VREF+ pin, so the ADC readings will be invalid.

JW

[abhijith_raj]

Hi @waclawek.jan ,
So there is no internal reference voltage to read ADC inputs, right?

[mƎALLEm]

No reference voltage: ADC not working as expected-> reading is invalid and there is no recovery mechanism to detect the unavailability if Vref

[abhijith_raj]

Hi @mƎALLEm ,
I am confused with the internal reference voltage VREFINT, can I use that as a reference if no external VREF+ is provided?

[mƎALLEm]

I've already answered that question in this thread.

You can use VREFBUF instead of the external VREF voltage but you need to enable VREFBUF in your application. and you should disconnect any other external VREF source and connect an external decoupling capacitor.

[TDK]

VREFINT has nothing to do with the ADC. It is not a voltage reference for the ADC.