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Many MOSFETs do not specify switching losses in their data sheets. Does this imply that the losses are too low to worry about? Too high for the device to be used in a switching application? Variable between units of the same product line? Or does it imply different things with different devices?

Example without losses: http://ixdev.ixys.com/DataSheet/DS100088(IXFN360N10T).pdf Example with losses: http://www2.microsemi.com/document-portal/doc_download/8195-aptm50hm75stg-rev4-pdf

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  • \$\begingroup\$ Can you provide an example of such MOSFET? Maybe the loses aren't very obviously provided. \$\endgroup\$ – AndrejaKo Sep 4 '13 at 16:20
  • \$\begingroup\$ @AndrejaKo Done. \$\endgroup\$ – Stephen Collings Sep 4 '13 at 16:27
  • \$\begingroup\$ Do you have an example of a datasheet that does specify switching losses? \$\endgroup\$ – The Photon Sep 4 '13 at 16:59
  • \$\begingroup\$ @ThePhoton Added. \$\endgroup\$ – Stephen Collings Sep 4 '13 at 17:03
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It implies that there are too many variables, so they won't guarantee that you get a certain performance.

The main variable with switching losses is the speed at which to turn it on/off and the frequency of switching. The speed of switching will depend on how much current you can drive the gate with, the inductance of the traces and pins, and the capacitance of the gate itself.

Of those variables, it is only the gate capacitance that is under control of the MOSFET manufacturer and so it is often just the gate cap that is listed in the datasheet.

Basically, for all MOSFET datasheets it should say: "Switching Losses: Your Mileage May Vary (typ)".

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  • \$\begingroup\$ The nature of the load plays a role too (inductive vs. resistive). \$\endgroup\$ – Adam Lawrence Sep 4 '13 at 17:32

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