7.3 mOhm Rds(on) at 45 A — the conduction-loss anchor
The IRFB7546PBF is an Infineon HEXFET in the StrongIRFET series, an N-channel MOSFET rated for 60 V drain-to-source with a continuous drain current of 75 A at 25 °C case temperature. The 7.3 mOhm maximum on-resistance at Vgs=10 V and 45 A sets the conduction loss floor — at 45 A the dissipation is roughly 15 W, which the 99 W package limit can handle with a proper heatsink. The drive voltage range (6 V to 10 V for rated Rds(on)) means it works with 5 V logic through a gate driver, but for the lowest resistance the gate needs the full 10 V rail.
Gate charge and switching speed
Total gate charge is 87 nC at Vgs=10 V, with an input capacitance of 3000 pF at Vds=25 V. For a 100 kHz switching frequency, the average gate-drive current needed is about 8.7 mA — well within a standard MOSFET driver. The 3000 pF Ciss means the driver must supply a peak current of roughly 1.5 A to hit a 50 ns rise time; a weak gate-drive source will stretch the switching edges and increase crossover loss.
175 °C junction — motor drive and power supply duty
In a motor-drive or DC-DC converter, the 99 W dissipation ceiling at case temperature 25 °C must be derated above that point — a typical TO-220 in still air has an RthJA around 62 °C/W, so without a heatsink the usable power is under 2.5 W at 25 °C ambient. The 3.7 V maximum gate threshold at 100 µA drain current means the device is fully off below 3.7 V, which is a standard logic-level threshold for 5 V systems.
ROHS3 compliant. The TO-220AB through-hole package is a standard 3-lead form factor — the same footprint as any TO-220 N-channel, making it a drop-in for existing layouts that use that package.