Output of Voltage reference buffer does not match expected value.

jugal · ‎2021-11-29

I set up the VREFBUF (using CubeMx) to use the internal voltage reference, with a SCALE of 2.048V. When i probe the Vref pin i see a voltage of around 2.2-2.3V, it changes slightly after ever power reset. It is a custom board with a G061c8 micro. The vref pin is not connected to any capacitors or any other pins.

I tried the same thing on a G071 nucleo board and i got exactly 2.048V on the Vref pin.

Any help is appreciated.

TDK · ‎2021-11-30

Does the board otherwise work (can it be programmed, blink LEDs, etc)? The simplest answer is a hardware issue with your custom board.

If you feel a post has answered your question, please click "Accept as Solution".

jugal · ‎2021-12-01

The board is functional.

waclawek.jan · ‎2021-12-01

VDDA is rock stable and high enough? VSSA is properly connected to GND? No bad solder joints?

Do you have DAC/ADC active? If yes, create a simple experimental program which does nothing just enables the VREFBUF.

Read out and check/post content of relevant registers.

> The vref pin is not connected to any capacitors or any other pins.

DS specifies min. 100nF in footnote 4 to table VREFBUF characteristics.

JW