The AUIRFSL8403 is an N-channel power MOSFET from Infineon's HEXFET® series, rated for 40 V drain-source and 123 A continuous switching current. The 3.3 mOhm maximum on-resistance at 70 A, 10 V gate drive is the figure that governs conduction losses in a high-current rail. The TO-262 through-hole package (I2PAK variant) suits designs where the heatsink mounts directly to the PCB or chassis — the tab is the drain, and the three pins are gate and source. Bulk packaging means it ships loose in tubes or trays, not taped for automated placement.
Gate drive and switching characteristics
Gate threshold voltage is 3.9 V maximum at 100 µA drain current — this sets the minimum gate drive for the device to start conducting. The total gate charge is 93 nC at 10 V, which determines the driver current needed to hit a target switching frequency; a 93 nC gate at 50 kHz draws about 4.65 mA from the gate driver, well within a standard driver's capability. The ±20 V gate-source rating provides margin against ringing on the gate node in a hard-switching topology — a snubber or gate resistor is still advisable if the layout has more than 10 nH of parasitic inductance in the gate loop.