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Is VREF+ pin required to be connected if VREFBUF is configured as an internal reference on STM32G4?

KHarb.1
Senior II

I began using an STM32G473 and the DAC outputs are acting funny. I have VREFBUF configured as an internal reference. Since I'm not using VREF+ as an output, I left the pin unconnected. I posted a thread about it and it was recommended that I connect VREF+ through a cap to ground.  I'm working with a custom board where this isn't possible so I can't test.

I haven't found anything in the documentation that would suggest leaving the VREF+ pin unconnected would have ill effects on DAC outputs. Is this documented anywhere?

 

Original thread:

https://community.st.com/t5/stm32-mcus-products/triangle-wave-dac-output-on-stm32g473-seems-to-be-stuck-enabled/m-p/659118#M240313

1 ACCEPTED SOLUTION

Accepted Solutions
KHarb.1
Senior II

The observational data was polluted by a raft of other issues but resolved with the data in the above replies.

View solution in original post

3 REPLIES 3

> Is this documented anywhere?

Sure.

waclawekjan_0-1712866314245.png

Importance of stable VREF+ for stable DAC is not a question, I suppose.

JW

PS. Please don't start new threads while discussing the same issue. Please select @AScha.3 's correct answer as  "Accept as solution" so that the thread is marked as solved.

STTwo-32
ST Employee

Hello @KHarb.1 

I suggest you to take a look at the reference design based on the STM32G4 Series on the  AN5093

Screenshot_2024-04-11-21-16-08-40_e2d5b3f32b79de1d45acd1fad96fbb0f.jpg

Best Regards.

STTwo-32 

To give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.

KHarb.1
Senior II

The observational data was polluted by a raft of other issues but resolved with the data in the above replies.