STM32WL31: Differences in published matching topologies

[Franz.1]

Hi! 

Starting a design with an STM32WL31K8V6. This is the 32 pin VFQFPN32 variant.

As far as I can see, there is no HW Reference PCB that covers the 32 pin package. Looking at the datasheet

https://www.st.com/resource/en/datasheet/stm32wl31kb.pdf

on p.32, there is Figure 10. "STM32WL31xx application circuit with SMPS, VFQFPN32 package" which shows the typical circuitry around the chip (i.e. the matching network).

However, looking into the details of AN5457, latter shows a different matching topology than the datasheet. It´s similar, but still...

https://www.st.com/resource/en/application_note/an5457-rf-matching-network-design-guide-for-stm32wl-series-stmicroelectronics.pdf

Since the AN5457 shows details on how to so the matching I tend to use the topology shown there but what is the reason that there are different references?

Thanks

[Franz.1]

Anyone ? Maybe @Gyessine 

[Filippo_Malleo]

Hi Franz.1, 

the AN5457 refers to the STM32WL5 product family.

If you are interested in STM32WL31 QFN32, you can refer to the Nucleo board for the WL3R product, since they are equivalent from RF point of view. 

You can find the schematics at the following links:
- MB2339-HIGHBAND-A02 Board schematic

- MB2339-LOWBAND-A02 Board schematic

You can consider these two designs as reference for QFN32 package, 4-layers PCB with IPD (integrated passive devices) solution instead of discrete matching network.

Best Regards,
Filippo