Страница 23.
Rated output power; PO = 200W.
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Power Mos
The Mosfet breakdown voltage is imposed; Bvdss ≥ Vout + Dvout + margin = 500V. The Rdson is selected taking
in to account the conduction power dissipation.
The formula for calculation is: Pon_max = Iqrms
2 · Rdon
i.e. considering Ron(t) = 0.7Ω the Pon_max = 2.15 · 0.7 = 3.3W.
Adding the switching (and the capacitive) losses we can estimate 8W to 10W total power dissipation.

Обсуждаемый мосфет - 0.22Ома.
И нафига их два ставить?