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I'v been searching mosfet for high power load project (DC 110V 100 Amp) and I found Fairchild FDL100N50F (TO-264) with maximum Power Dissipation 2500W. According to data sheet, the Max SOA DC (continuous not pulse) at 100v is around 20A, my question is, considering the package/dimension is it really safe to apply 100v at 20 amp, do I really need mosfet in SOT-227 package such as IXFN82N60P which surprisingly (for me) has less maximum Power Dissipation @ 1040 W.

Thankyou for your answer, and pardon my english

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Question is, can you keep the FET within it's SOA range ?

The package by itself does not matter ! What matters is, can you keep the FET's junction below a certain temperature so that it stays in the SOA ? It is always easier to spread the load between as many FETs as possible to keep things cool.

Also, these FETs are made for switching, so Rds is either as high or as low as possible. They might perform terrible when you try to keep them at a predetermined Rds because of their high K (Ids / Vgs). Note how that K I just mentioned is not mentioned in the datasheet (for the Fairchild one anyway) !!!!

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The datasheet says it is (just) safe. If you believe the datasheet, it is. The anecodotal evidence I have is that SOA curves for MOSFETs are calculated and may be in error on the wrong side, so I would not be surprised if the MOSFET failed catastrophically under those conditions.

Also, 2500W is kind of a theoretical maximum with the case held at 25°C. Unless you're running chilled water through the heatsink (feasible, but expensive- about a 1HP chiller) you're unlikely to achieve that with 2500W flowing out of the case.

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