The STD2N95K5: The 950 V drain-source rating provides headroom for ringing spikes during hard-switching transitions. That 5 Ohm figure at the operating point means conduction losses of 5 W at full rated current — the DPAK package with the exposed tab on the primary-side copper pour handles that dissipation if the board has adequate airflow or a heatsink. The low Qg also reduces the cross-conduction interval during the Miller plateau, which helps keep switching losses in check at frequencies up to 100 kHz or so.
Thermal and switching — the numbers that shape the layout
Maximum power dissipation is 45 W at the case with the tab soldered to a large copper area. Input capacitance is 105 pF at 100 V drain — a low figure that keeps the gate-drive energy per cycle small. That also means the switching node rings less at turn-off, so the snubber network can be a simple RC across the drain-source without over-damping the waveform. The threshold voltage is 5 V maximum at 100 µA drain current.
Package and sourcing — DPAK footprint, active production
The STD2N95K5 comes in a TO-252-3 DPAK package, surface-mount with two leads and a tab. The base product number is STD2N95.