30 V, 4.1 mOhm — the conduction loss floor
The IRFH8324TRPBF is an N-channel enhancement-mode MOSFET from Infineon's HEXFET® family, rated at 30 V drain-to-source and 4.1 mOhm typical on-resistance at 20 A with 10 V gate drive. That Rds(on) figure defines the steady-state conduction loss in a synchronous buck or load switch — at 20 A the dissipation is under 1.7 W, which the 3.6 W (Ta) / 54 W (Tc) power rating can handle with a reasonable copper pad on the PQFN (5x6) footprint.
Current rating split: 23 A at Ta vs 90 A at Tc
The dual current rating — 23 A continuous at 25 °C ambient (Ta) and 90 A at the case (Tc) — tells the thermal story. The Ta number applies when the part is free-air on a standard PCB without a dedicated heatsink; the Tc number assumes the PQFN's exposed pad is soldered to a large copper plane or an external heatsink.
Gate drive and switching budget
Total gate charge is 31 nC at 10 V, with a drive voltage range of 4.5 V to 10 V for the specified Rds(on). At 100 kHz switching, the average gate drive current is 3.1 mA — a standard gate driver IC handles that easily. The 2380 pF input capacitance at 10 V drain bias sets the switching loss term; a 10-ohm gate resistor gives a ~24 ns rise time, fast enough for most mid-frequency converters without excessive ringing.