Part Number: LM5020
We have two power supplies using LMM5020MM-1 which could not be powered up near or under -40ºC. If the PWM IC are powered up successfully above -30ºC, then the PWM IC can continuously to work even under -40ºC. Pin SS (soft start) is held low voltage (0.74V across external 0.01uF cap) all the time during -40ºC start-up, indicating "Softstart Current Source" (10uA) may be disabled. Could you check if "Softstart Current Source" is sensitive to -40ºC or lower?