650 V, 18 A, 155 mOhm — what these ratings mean for your switching load
The TK155E65Z,S1X: The 650 V drain-to-source breakdown voltage places it comfortably in the 400–600 V bus range common to PFC stages, flyback converters, and two-switch forward topologies — the voltage headroom above a 400 V rail covers switching transients and line surges without avalanche stress.
Total gate charge is 29 nC at 10 V, and input capacitance measures 1635 pF at 300 V drain bias. For a 100 kHz hard-switched converter, the gate driver must supply an average current of about 2.9 mA just to charge the gate — well within a standard 1 A driver, but the peak current at turn-on is set by the driver's source impedance and the gate resistance. The 29 nC figure also lets you estimate switching losses: each transition dissipates roughly 0.5 × Vds × Id × (tr + tf), and the gate charge determines how fast the Miller plateau is traversed.
TO-220 package — thermal and mechanical fit
The through-hole TO-220-3 package (supplier device package TO-220) dissipates up to 150 W at the case, but the real thermal limit depends on the heatsink and mounting torque. The 150 W figure is the absolute-maximum rating at Tc=25 °C; derate linearly above that case temperature per the datasheet's thermal resistance curve.