STM32H750VBT6 VREFBUF pin

[Damien Ratazy]

Hello,

I'm a bit confused to how use the VREFBUF on this MCU.

I want to use the internal voltage reference (SCALE 0 : 2.5V) for better ADC accuracy.

Do I have to connect the VREF+ pin (20) to AVDD (+3.3V) or I've to connect it to a 1uF + 100nF capacitors only?

[waclawek.jan]

Connect it to a 1uF + 100nF capacitors only.

JW

[Damien Ratazy]

Okay, and apart of the CubeMX config (VREFBUF = Internal Voltage Reference with SCALE 0), does the ADC automatically choose that VREFINT reference voltage without any supplemental software/register manipulation in my C code?

Thanks

[waclawek.jan]

There is no change from ADC point of view.

ADC's reference is always the VREF+ pin.

Here, you are connecting an internal source to VREF+ pin.

JW

[Damien Ratazy]

So that VREFINT voltage is set to 2.5V with SCALE0, connected to the pin 20, filtered by the 1uF+100nF external caps connected to this pin, and then the ADC uses that VREFINT for its reference.

I'm correct?

[waclawek.jan]

I don't know what's pin 20 as I am not going to look up your STM32's DS; but if it's VREF+ then yes.

If in doubts, getting a cheap Nucleo board to test any of the hardware features may be a good idea.

JW

[Damien Ratazy]

Pin 20 is indeed VREF+ on the STM32H750VBT6.

I've to try this.

Thanks for your answers  🙂