Hi Everybody,
I have an issue with STM32L433CCU6, when it's entering or exiting STOP 1 mode at temperatures from -36dC to -29dC uP completely freezes
Basic overview of program:
- watchdog is set to 25 seconds
- clock: HSE 8MHz -> PLL 16MHz (SYSCLK) -> /2 -> HCLK 8MHz
- wake up clock is HSI
- Clock Security System is running
- uP is going to STOP 1 mode whenever it is possible
- uP is woken up by LPTIM external trigger or by RTC every 20 seconds to reset watchdog
- BOOT0 pin is grounded
- NRST pin is left floating
Overview of behavior:
- when STOP 1 mode is disabled uP works from -60 dC to 70 dC without any problem
- when STOP 1 mode is enabled:
- from -29 dC to 70 dC: uP works fine
- from -36 dC to -29 dC: after several minutes uP freezes
- from -60 dC to -36 dC: uP occasionally freezes
- sysclk is nominal during whole temperature range (USART communication)
- VDD is nominal during whole temperature range and also in freeze state
- consumption measured at the input of the STEPDOWN converter (from 15 V to 3.3V) is about 4 uA during STOP 1 mode
- when uP freezes then consumption rises to value about 100 uA
- uP in this mode cannot be reset with NRST
- communication with uP through SWD cannot be established using ST-LINK V2 (connected under reset) and ST-LINK utility
- when uP is under debug in OpenStm32 environment in moment of freezing GUI shows failure
- uP stays in freeze mode also after reaching room temperature (even after several hours)
- normal state can be reached only after disconnecting and reconnecting power voltage
- after power toggle at mentioned temperature range (from -36 dC to -29 dC), uP runs several minutes and freezes again
- this state was observed on 4 pieces of independent PCBs and during several tests in Cryostat or Climatic Chamber
I want to ask whether you experienced similar behavior even at room temperatures, and how to solve this problem.
I will be very grateful if you help me solve this issue. Thanks.
Tomas
