STM32WB55 BLE connection issues at higher temperature.

[BStic.2]

Hello!  We are a bit stumped here.  We have a product that we are testing at 65C and it seems that the bluetooth connection keeps dropping at this temperature (Connection timeouts).  We are running from a 32K LSE and 32M HSE crystals.  All our parts are confirmed to be good to 80C.  There seems to be a host of other various issues that pop up at this temperature.  Ive tried setting the LSE drive to HIGH and increasing the flash latency, but it does not seem to impact the behavior.  Any ideas?

[STTwo-32]

Hello @BStic.2 

The 16MHz crystal is not enough for the RF block. It is mandatory to use a 32MHz Crystal in order to achieve the right timing accuracy. This is one of the key points to check/change.

Best Regards.

STTwo-32

[BStic.2]

Apologies, that was a typo.  We are using 32M for HSE.  

[STTwo-32]

Hello @BStic.2 

Sorry for my late feedback, 

What are the part number of HSE and LSE crystals on this customer board? What is the marking on the WB55 populating the board? Does it happen on many boards if any?

Best Regards.

STTwo-32