Slelecting Voltage Reference pins

[rabbani_sk]

Hi,

STM32F405 Microcontroller(Package: LQFP64) does not have Vref pins, Can we select any alternate pins as Vref pins. Please Suggest.

[Andrew Neil]

What does the datasheet and/or Reference Manual tell you?

[SofLit · Accepted solution]

Hello @rabbani_sk and welcome to the community,

The answer is provided in the datasheet:

"When VREF+ and VREF– are not available, they are internally connected to VDDA and VSSA."

So to answer your question: No. Vref is not exported externally on LQFP64 and none of the GPIO pins can be used for Vref pin.

Hope it does answer your question.

[rabbani_sk]

Hi Thanks for your reply,

Requirement: I want to set 3V for the internal reference voltage which is connected to VDDA and VSSA.

Query: Is there any software configuration to set it 3Volts or any other approach to set Internal Vref.

Thank you

[SofLit]

Hello,

You need always to refer to the documentation especially datasheet and reference manual of the given product.

Table 14 from the product datasheet, answers your question. It mentions the minimum voltage for VDDA according to a certain conditions. Also read the notes under the table.

No need for any software configuration. It's something related to electrical specifications.

All you need is to take care of the VDD/VREF value in your calculation in voltage reading especially when your are using ADC or generating voltage when using DAC.

Hope I answered your question.

[TDK]

> STM32F405 Microcontroller(Package: LQFP64) does not have Vref pins, Can we select any alternate pins as Vref pins. Please Suggest.

No, this is not possible on the LQFP64 package. It will always be the same as VDDA which must be the same as VDD.