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jugal
Associate II
November 29, 2021
Question

Output of Voltage reference buffer does not match expected value.

  • November 29, 2021
  • 2 replies
  • 976 views

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.

This topic has been closed for replies.

2 replies

TDK
Super User
November 30, 2021

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

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jugal
jugalAuthor
Associate II
December 1, 2021

The board is functional.

waclawek.jan
Super User
December 1, 2021

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