150 V, 78 A HEXFET — the conduction-loss benchmark
The IRFP4321PBF is an N-channel HEXFET power MOSFET from Infineon's established HEXFET series, housed in a through-hole TO-247AC package. It is designed for high-current switching applications where low on-resistance and ruggedness matter — think motor drives, DC-DC converters, battery isolation switches, and industrial power supplies.
Gate charge and switching speed — what 110 nC means for the driver
Total gate charge is 110 nC at a 10 V gate drive. Input capacitance is 4460 pF at 25 V Vds.
Thermal budget and mounting — the TO-247AC reality
Maximum power dissipation is 310 W at the case temperature. That number assumes an ideal heatsink at 25°C case — real-world derating is governed by the junction-to-case thermal resistance implicit in that figure. The through-hole TO-247AC package requires a heatsink with a mounting hole for the M3 screw through the tab.