55 V, 31 A N-channel — the TO-220FP workhorse
The IRFIZ44NPBF: The TO-220-3 Full Pack (TO-220AB Full-Pak) isolates the tab electrically, so no insulating washer or pad is needed between the device and the heatsink — a practical advantage in assembled-through-hole designs where the heatsink shares a chassis ground.
24 mOhm on-resistance — conduction loss ceiling
Maximum Rds(on) is 24 mOhm at 17 A drain current with 10 V gate drive. The 45 W power dissipation limit at the case (Tc) means the thermal design must keep the junction below 175 °C under worst-case load. Gate charge totals 65 nC at 10 V. The 1300 pF input capacitance at 25 V drain bias means the driver's peak current capability sets the rise and fall times.
Through-hole full-pack — heatsink without the washer
The TO-220-3 Full Pack (TO-220AB Full-Pak) uses a fully moulded plastic body that isolates the mounting tab. No separate insulating pad or bushing is required when bolting to a heatsink, which simplifies assembly and reduces thermal interface resistance.