STM32C011F6 and uC with common input VDD & VDDA - hardware design

[JGreg.2]

Hello,

It appears that it's the first time for me to deal with a uC (here ST32C011F6U6TR) which has a common input for VDD (general votlage power supply) and VDDA (analog voltage power supply).

The project I am working on has a very sensitive analog parts and has its own analog power voltage (generated from VDD with filtering) and I can not take the risk to bring noise to it.

So, I am wondering if there is application note (which I didn't find) explain how to design it ?

If not, could you tell me what is the best way ?

- bring the VDD to the VDD/VDDA input but the ADC Vref will be noisy

- bring the VDDA to the VDD/VDDA input but it could bring noise to VDDA and then to all my analog parts

- another way ?

Thank you in advance,

Best regards,

[nehakakar]

If you’re worried about noise, you could try using a filter (like an LC or RC filter) between VDD and the VDD/VDDA pin to reduce it. Using a low-noise voltage regulator for VDD can also help keep things stable for the sensitive analog parts.

[STOne-32]

Dear @JGreg.2 ,

You can checkout our Application Note : Getting started with STM32C0 MCU hardware development - Application note

For this 20 pin package , all VDDA/VDD/VREF+ are internally bonded, not possible to have that Option and you may need a bigger package having a separated VREF+  . See section 1.1  .  you can see a LQFP48 Package stm32c031k4.pdf  but of course it might be with different size and price in comparison to STM32C011.

Hope it helps you.

STOne-32.

[JGreg.2]

This is what I am already doing (using RC filter between VDD and VDDA).

Now, the point is: if I use VDDA for the uC power supply, will it bring noise to it and then to the analog part ?

Maybe I should create and third one just for the uC, which will be less noisy than VDD and will not bring noise to my analog part? Is it common to do so ?

[JGreg.2]

Dear STOne-32,

Yes, I had already checked that AN but It doesn't explain "how to"  for STM32C0 with a common VDD/VDDA input.

So, is there any other AN explaining how to filter and how to deal with that specific uC input ?

As I said at my previous reply, maybe create a third power supply just for the uC ?