40 V, 75 A N-channel in D2PAK — conduction loss floor
The AUIRF1404S is an Infineon HEXFET N-channel MOSFET rated 40 V drain-source with a continuous drain current of 75 A. The headline on-resistance is 4 mOhm maximum at 95 A drain current and 10 V gate drive — this is the conduction loss floor at 25 °C junction; actual Rds(on) rises with temperature per the normalised curve, so budget headroom in the thermal path for a 175 °C junction ceiling.
Gate charge — 200 nC at 10 V
Total gate charge Qg is 200 nC at 10 V. For a 100 kHz switching frequency, the average gate-drive current is 20 mA; the peak current from the driver must be sized to charge 200 nC within the desired switching interval — a 2 A driver delivers a 100 ns rise time. The ±20 V Vgs rating gives margin for gate overdrive in noisy power stages.