Minimum current requirement for external VREF+ on STM32G474

[nbsown]

Hi ST Community,

I'm using an external precision voltage reference connected to the VREF+ pin of the STM32G474.

I would like to know:

• What is the minimum output current capability required for the external VREF source?
• Is there any specification for the average or peak current drawn from the VREF+ pin during ADC conversions?
• Does the required current depend on the ADC sampling rate, the number of ADCs operating simultaneously, or the sampling time?
• I couldn't find a clear specification for the VREF+ input current in the datasheet or reference manual.

Any explanation or recommendation would be greatly appreciated.

Thank you!

[Andrew Neil]

Does this answer your question?

https://www.st.com/resource/en/datasheet/stm32g474re.pdf#page=139

via: https://www.st.com/en/microcontrollers-microprocessors/stm32g474re.html

[nbsown]

Oh, it looks like I missed it. Thank you very much!

[MasterT]

Q: 

• Does the required current depend on the ADC sampling rate, the number of ADCs operating simultaneously, or the sampling time?

Since architecture is SAR, and there are no pre-charge buffers on signal inputs and on reference inputs, than rough approximation is that I-ref = I-inputs. And I-inputs = V / R, where R = 1/ 2*PI()*Freq*C, C - sampling and hold, Freq - sampling rate. Sure, multiply by N if more than 1 ADC operating.

[nbsown]

Thank you very much!