The role of AVDD on Nucleo-L476RG

[mdiro]

Hi people!

I am currently using a Nucleo-L476RG connected to an analog sensor. On the datasheet of the mcu, in the ADC section, I can read "One external reference pin is available on some package, allowing the input voltage range to be independent from the power supply". If I understood it correctly, this means I can supply the ADC to get a different ADC range. This would be great for my application because I would need an ADC range of 0-10V.

My first question here is the following: assuming I understood it correctly, do I just need to feed the AVDD pin of my nucleo board with a 10V reference to get the 10V ADC range? I assume I also have to desolder the bridge SB57 as reported in the nucleo datasheet:

Question 2: in case my assumptions are correct, do I also need to feed the GND pin just below the AVDD pin?

Question 3: what about VREFINT? I don't understand its influence in case I supply my ADC with 10V.

Thank you all in advance :)

[waclawek.jan]

 

JW

[S.Ma]

All microcontrollers can't support high voltage due to physics: process oxide thickness.

Vdda is the supply to the noise sensitive analog blocks such as adc, comparators, etc...

It can be sometime lower than the digital section, and noise decoupled. The datasheet electrical tables will explain the allowed voltage ranges. For adc, an external op amp to scale down amd buffer the incoming signal is a good starting point.

At the beginning, no need to rework the nucleo until optimisation and noise reduction becomes necessary to move forward.

[mdiro]

Thank you for your answer. Is there any way to measure constantly the ADC internal supply?

[S.Ma]

Normally Vref internal channel which is bandgap voltage, which you can deduct adc supply voltage. If adc is running in loop, analog watchdog can be also used to detect threshold crossing and interrupt, if neeeded.