What switching frequency to choose for a power supply?

  • It is assumed that the design will use some kind of "Soft Switching", and/or "Low Losses/Non Dissipative Snubbers". Today, for a new, competitive power supply design, just using "Hard Switching" is no longer an option.
  • We believe that choosing the switching frequency must be done at the beginning of a new design, taking in consideration: power level, cooling method, application specifics.
  1. Power levels 0-50W: any switching frequency between 100kHz and 1MHz may be a good choice, depending of application.
  2. Power levels 50W-500W: best choice would be between 200kHz and 500kHz. Use 200kHz for a higher efficiency and 500kHz for a higher density and easier filtering.
  3. Power levels 500W-5kW: best choice would be between 100kHz and 200kHz. Use 100kHz for a higher efficiency; otherwise 200kHz is the best choice.

Choosing a much different switching frequency than those suggested above, may work for a while, but soon you will discover that your competitor has a product with a higher power density, or better efficiency. Do not find out too late that your power supply is not competitive.

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