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February 7, 2025
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STM32H533 ADC VDDA, VREF+ and input voltage range

  • February 7, 2025
  • 2 replies
  • 848 views

I'm a little confused about the descriptions of the ADC VDDA, VREF+ and input voltage range.

Do I understand it correctly that

VDD is the device supply

VDDA is the ADC supply

VREF+ is the ADC reference

It says VREF+ can be supplied internally as 1.8 V, 2.048 V or 2.5 V. Range for external Vref+ 1.8V - VDDA.

If I want to use an internal reference and I connect VDDA to VDD to save components what is then my input voltage range?

Is the input voltage range VSS - VDDA, VSS - VREF+ or VSS - VDD?

    This topic has been closed for replies.
    Best answer by AScha.3

    So at first : which H533 ? because with small case,  vref = vdda :

    see ds:

    AScha3_0-1738946194344.png

    +

    vdda usually = vdd , connected. (on low pin count case also vref+ fixed to vdda, no other/internal vref possible here.)

    ADC supply then vss ... vdda (= vdd); input range always vss...vref+;

    so if you can select internal vref-> vrefbuf->adc vref+ , input range vss...vref .

    2 replies

    AScha.3Answer
    Super User
    February 7, 2025

    So at first : which H533 ? because with small case,  vref = vdda :

    see ds:

    AScha3_0-1738946194344.png

    +

    vdda usually = vdd , connected. (on low pin count case also vref+ fixed to vdda, no other/internal vref possible here.)

    ADC supply then vss ... vdda (= vdd); input range always vss...vref+;

    so if you can select internal vref-> vrefbuf->adc vref+ , input range vss...vref .

    thansenAuthor
    Graduate
    February 10, 2025

    Thanks for the clear answer.