Common Temperature Ranges
Standard commercial-grade switching power supplies: 0°C to +40°C; Industrial-grade: -20°C to +70°C; Military or custom grades can reach -40°C to +85°C. Operation beyond these ranges may lead to failure.
Derating Is Essential at High Temperatures
When the ambient temperature exceeds the rated upper limit (e.g., 40°C), derating must be applied. A typical rule: for every 10°C increase in temperature, the output power should be reduced by 10%. For example, at an ambient temperature of 50°C, an originally 100W power supply should be used at only 80W. Otherwise, the lifespan of electrolytic capacitors will be drastically shortened, and over-temperature protection may even be triggered.
Low Temperature Precautions
Low temperatures (e.g., below -20°C) may cause difficulty in starting the power supply due to reduced activity of the electrolyte. In such cases, wide-temperature models (-40°C) should be selected, and preheating or maintaining a light load operation before power-on should be ensured. In summary, refer to the power supply’s “temperature vs. load curve” based on the actual ambient temperature and strictly comply with the derating requirements.