STM32L476JGY6TR enters to Bootloader during -40°C Temperature test

[Prithivi]

STM32L476JGY6TR enters to Bootloader during -40°C Temperature test, once the temperature decreases to -25°C the MCU operation is normal. I have even added PD to Boot0 pin, even the results are same. I don't find any problem during positive temperature tests, the MCU operation is normal. 

[Tesla DeLorean]

The BOOT0 should have a pull-down in any case. Leaving it floating will cause unreliable behaviour.

Are you sure it's in the System Loader? Or that you have some other issue with the PLL or Oscillator bring up and it fails into Error_Handler() instead?

Would suggest checking supplies and other components that might have their own issues at lower temperatures. Add code in Reset_Handler to bring up a GPIO / LED you can use to check code execution.

[Prithivi]

In my circuit the boot pin is connected with diode, but the PD is placed before the diode, but not directly to the boot pin. The diode made problem during -30°C to -40°C and enters in to boot mode. The problem is solved by removing Diode and PD is placed near to BOOT pin. 

[waclawek.jan]

Thanks for coming back with the solution. Please click on "Accept as solution" in your post so that the thread is marked as solved.

JW