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, I am following up on this topic as it is important for us but somehow left idle for some time. My question here is do we have any risk/problems with the STM32WB schematic which is designed with VDD of 1.8V.

Please look into the following Pin connection where I am looking for clarification:

• Pin 68: VDD: 1.8V
• Pin 1: VBAT: 1.8V
• Pin 8: NRST: 1.8V
• Pin 13: VREF+: 1.8V
• Pin 14: VDDA: 1.8V
• Pin 30: VDD: 1.8V
• Pin 33: VDDRF: 1.8V
• Pin 43: VDDSMPS: 1.8V
• Pin 45: VDD: 1.8V
• Pin 55: VDDUSB: 3.3V

Additionally, for programing/debug we are planning to use official ST-Link V2 and the connection with 1.8V P8 header is shown above. 

Please let me know if this design (considering all above-mentioned pin connections) is okay or are there any problems that need to be corrected.

Looking forward to the replies that will greatly help us.

Thanks.

 

 

To ensure proper power and RF design for the STM32WB55REVx, check that VDD is stable at 1.8V with adequate decoupling capacitors near power pins. Follow STMicroelectronics’ layout guidelines for RF, ensuring a clear ground plane and proper antenna matching for minimal interference. If possible, share your schematic for a more detailed review! https://marumenuprices.com

[Sangratha]

Hi @unknown thanks for your inputs. Please find the schematic attached. I shared the same earlier. Is this good enough or do you need any further information. I will be happy to share. Thanks.