How to use Vrefint when Vref+ is tied to Vssa?

[krom]

Hi,

I wanted to use STM32H743 with TFBGA100 package in a new project. Unfortunately this package does not provide Vref+ pin and it is internally tied to Vssa. I don't understand what is the reference source for ADCs and DAC, can I use VREFBUF in hold mode? But then where should I connect the capacitors mentioned in an5690?

Regards

[waclawek.jan]

> I don't understand what is the reference source for ADCs and DAC

VREF+ (which is tied to VDDA).

> can I use VREFBUF in hold mode

No. You can't use VREFBUF in this package.

JW

[Muhammed Güler]

There is information in the datasheet that in lower models, if there is no vref pin, VREFBUF will not be present. I couldn't see such information in your MCU datasheet.
On MCUs with VREFBUF, if VREFBUF is not set, VDDA is used instead of VREF+.
Since there is no relevant information in the datasheet, there are three scenarios.
When you try to install VREFBUF you will get a hardfault (this is most likely to happen).
You successfully set VREFBUF to the internal reference voltage (probably not)
You don't use VREFBUF at all, vda is used as VREF+.

[krom]

Thank you for your replies. It seems strange to me that the LQFP100 package has a Vref+ pin and the TFBGA100 does not. The H7 series has great ADCs at first glance, but unfortunately every package has its limitations. Fortunately, the voltage level Vdda can be different from Vdd, and I will use two different voltage sources. Is there anything else I should do in this situation to get the most accurate ADC measurement results? I know the general recommendations that STm presents in its documents.