If the switching power supply uses a thermistor to suppress the inrush current; it could cause a failure to

start up at low temperature (such as –10°C) due to temperature sensitivity. Following

are some methods to solve this problem:
(1) Keep the power supply at standby status (Keep AC source ON and then switch

the output ON/OFF).
(2) Use heater to increase the ambient temperature of switching power supply (3) Reduce output load.

If the working temperature on the spec is -10°C~ 50°C and we want to operate it at -20°C, we should pay attention to the following issues:

  1. (1)  Relative humidity should be low to prevent ice formation.
  2. (2)  The output ripple will be larger.

(3) Since we usually use the thermistor as the inrush current suppresser and the

thermistor will increase its resistance when the temperature goes down. It is possible that the power supply may take a long time to start up or there could be failure to power up.

(4) We can not guarantee the extent of reduction in functionality when the S.P.S. is working out of the specification range.

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