Low Rds(on) for high-current switching
The AUIRFU8405 is an N-Channel HEXFET MOSFET from Infineon, rated for 40 V drain-source and 100 A continuous switching current. The 1.98 mOhm maximum on-resistance at 90 A and 10 V gate drive means conduction losses stay low even at high load — the part dissipates 163 W at the package limit, so the real thermal ceiling is set by the heatsink and ambient, not the die.
Gate drive and switching budget
Gate threshold voltage is 3.9 V maximum at 100 µA drain current, so a 5 V logic-level drive turns it on fully. The total gate charge of 155 nC at 10 V sets the driver current needed for a target switching frequency — a 100 kHz PWM cycle drawing 155 nC per transition requires an average gate current of 15.5 mA from the driver, well within a standard gate-driver IC's capability. The ±20 V maximum gate-source rating gives headroom for gate-drive overshoot in hard-switching topologies, but the 0.0052 µF input capacitance means the driver must source and sink enough peak current to charge and discharge that capacitance within the dead-time budget.
The IPAK (TO-251) through-hole package suits boards where a screw or clip heatsink mounts directly to the tab — common in power supplies and DC-DC converters where the tab is the primary thermal path.