STM32WB55REVx Custom board Schematic Review

[Sangratha]

I am working on a new project which is based on STM32WB55REVx MCU. I have designed the schematic as shown based on the VDD 1.8V. I would like to understand whether the power lines and RF design is properly done, or it needs some changes. I would appreciate for all helpful inputs. Thanks.

[STTwo-32]

Hello @Sangratha @and welcome to the ST Community.

I’m not an expert on the RF design. This is not an easy task. If you want to make sure that your design is fine, I suggest you to contact a privet RF design expert to verify your design. Else, you can always refer to this mooc(include some application notes that can help too. And also link to the training in YouTube), the AN5290 and the AN5165 for RF Design.

Best Regards.

STTwo-32

[Sangratha]

Thanks for your reply and providing the useful links @STTwo-32. While I am going through these documents I can see that some of the considerations are already taken in the schematic, and I am looking if there is anything missed.

Meanwhile, could you please help me in checking the power supply lines connections. I have designed to operate with 1.8v VDD. Is there anything missed here as there are multiple power pins on this STM32WB55 MCU for different domains. 

Thank you.

[Andrew Neil]

At RF, it's not just the schematic that needs to be correct - you also need to give careful consideration to the layout.

You really do need an RF expert for that!

Like @STTwo-32,  I am not an RF expert.

[Sangratha]

Hi @Andrew Neil sure, I got your point. Thank you.

I am also carefully looking at the layout and also some documents those have some related guidelines.

Anything other than RF in this schematic which you would like to highlight such as power, clock, reset, boot etc connections. Is it designed correctly?

Thanks.

[Andrew Neil]

I don't see any provision for programming/debug?

Are you sure your crystal capacitor values are correct? See AN2867.

Other things also sensitive to layout:

• Crystals & associated capacitors;
• Supply filtering/debouncing.

[Sangratha]

Hi @Andrew Neil Thanks for giving your inputs.

Here is the provision for programming/debug?

 Regarding crystal for HSE 32MHz and for LSE 32.768KHz is chosen as per the recommended values. I am checking the capacitor values around crystal.  

Could you please 1.8v connection to VDD, VDDA, VREF+, and VBAT. Is it correctly done? I am using 1.8V for the first time with this MCU so I would like to make sure that it will work fine. Could you please have some inputs on that.

Thank you.