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RHelv.1
Associate III
April 20, 2023
Solved

VREFBUF is inaccurate, causing ADC and DAC peripherals to be innacurate

Hello, I have two different projects in parallel right now, both of which use STM32G0B1 MCUs. On both projects, with completely seperate hardware, the VREFpin that connects to the internal VREFBUF peripheral is innacurate. These pins are just brought out to test points, nothing more. While configured for a 2.5V output, they measure about 2.9V and have more noise on them than I would expect for a reference voltage. Register values are as follows:

VREFBUF_CSR: 0xD

VREFBUF_CCR: 0x18

I've done other STM32 projects using VREFBUF without issues. Is there something different regarding the STM32G0B1 parts? Is anything needed in hardware to support VREFBUF? Our VDD is 3.3V.

Thanks,

Rob

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Chris21
Chris21Best answer
Associate II
April 20, 2023

Datasheet Power Supply schematic shows 100 nF and 1uF connected to VREF+.

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5 replies

Chris21
Associate II
April 20, 2023

Do you have appropriate capacitance connected to VREF+?

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RHelv.1
RHelv.1Author
Associate III
April 20, 2023

I do not. Is this required? @Community member​ 

Chris21
Associate II
April 20, 2023

Yes, according to STM32G0-Analog-Voltage-reference-buffer-VREFBUF.pdf STproduct training document.

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RHelv.1
RHelv.1Author
Associate III
April 20, 2023

Thank you!