Normally, SPS with fan built-in has a certain weakness such as unavoidable noise, vibration, additional power consumption, unexpected mechanical failure, short term reliability, dust debris, etc. On the contract, fanless SPS are smaller, more reliable and more flexible with lower noise. For the understanding of thermal characteristics of fanless SPS and SPS with fan built-in, different thermal dissipation methods of SPS will be introduced below.

SPS efficiency and power loss

Efficiency is the percentage ratio of total output power to input power. This is normally specified at full load under nominal input voltage. It is impossible to attain 100 % efficiency due to energy dissipated in the form of heat in passive and active components, such as switching devices, junction-based devices, capacitors, inductors, and so on. However, it is still possible to achieve above 95% efficiency by suitable electrical design, thermal design and component chosen. Electric characteristic and dissipation could be affected due to low energy efficiency, and excessive power lose can even decrease the life time of power supply, as well as deviation of electric characteristic performance.

SPS power levels and thermal dissipation methods

Based on different application, thermal dissipation methods can be different. Generally, natural convection, forced convection, and water cooling are common thermal dissipation methods and possess different thermal dissipation capabilities. Please refer to the following description of comparison based on different thermal dissipation methods.