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Associate II
August 7, 2024
Solved

VREF Internal voltage reference G431 series

  • August 7, 2024
  • 4 replies
  • 2506 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.

4 replies

TDK
TDKBest answer
August 7, 2024

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

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CrazyChelAuthor
Associate II
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.

waclawek.jan
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
Associate II
August 7, 2024

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