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Are these two concept the same or different for semiconductors? Some power MOSFETS have power ratings in the hundreds of watts, and that's way too high for heat loss.

I try to understand 'power dissipation' as in power these devices can sustain/allow passing. For MOSFETs, it's Vds * Id+Vgs * Ig. For diodes, it's Vdrop * ID. Also, where does the energy get dissipated to? Other than becoming heat that causes the inefficiencies.

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  • \$\begingroup\$ "Too high" in what sense? Note that dissipation is the average of electrical power. These components also deliver reactive power (junction capacitance, lead inductance), which is included in the instantaneous measure, but averages out over time. There are no side effects besides heat, at least not that are better expressed as other characteristics. \$\endgroup\$ Aug 29 at 1:19
  • \$\begingroup\$ MOSFET power and current as listed in datasheets ratings are pretty much imaginary laboratory test conditions. I ignore them. Calculate it yourself based on your conduction and switching losses. \$\endgroup\$
    – DKNguyen
    Aug 29 at 1:34
  • \$\begingroup\$ Do you need to make a distinction between pulse power and continuous power? The former is given in the SOA graph, and for us and ms pulses can be very large. The latter is given by the heatsink capability, and can be several orders of magnitude less than pulse capability. \$\endgroup\$
    – Neil_UK
    Aug 29 at 7:13

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