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Graduate
August 7, 2024
Solved

VREF Internal voltage reference G431 series

  • August 7, 2024
  • 2 replies
  • 1204 views

Hello,

Can anyone suggest whether or not I need to connect external capacitors to the VREF+ pin if I plan to use VREF only for the onboard DAC?
Could this be a hardware problem?
STM32G431CBT6. The problem is that on the oscillogram I see oscillations with an amplitude of approximately 490 mV on the VREF+ pin. This is when Scale 2 is set to 2.9 V. If I reduce to 2.5V, the swing will be almost 1V overall. Nothing but the 1:10 oscilloscope probe is connected to the VREF+ pin on the board.
Below are the screenshots.

Settings.png

Oscillogram.png

Pinout.png

Capacitors.png

    This topic has been closed for replies.
    Best answer by TDK

    Yes, it needs capacitors if you are using the DAC, per the datasheet and the hardware design guide.

    2 replies

    TDKAnswer
    Super User
    August 7, 2024

    Yes, it needs capacitors if you are using the DAC, per the datasheet and the hardware design guide.

    CrazyChelAuthor
    Graduate
    August 7, 2024

    Thank you! The question is closed.
    I have already connected 0.1 µF and 20 pF. Now I can switch between different ref values.

    Super User
    August 7, 2024

    > I have already connected 0.1 µF and 20 pF.

    I don't think these are the values required by the datasheet.

    JW

    CrazyChelAuthor
    Graduate
    August 7, 2024

    Thank you, I also noticed that this is not enough, I will increase it.