Automotive power switching with the AUIRFR4104
The AUIRFR4104 is an automotive-grade N-channel HEXFET MOSFET rated for 40 V drain-source and 42 A continuous switching current. The 175 °C maximum junction temperature gives headroom above the 125 °C under-hood ambient — the die can absorb transient thermal spikes from stalled motor starts or short-circuit events without immediate derating.
The ±20 V Vgs absolute maximum means the gate can tolerate 12 V battery transients and 24 V nominal rails without external clamping — but a 15 V zener across gate-source is still good practice for inductive-load flyback events.
Package and board integration
Surface-mount D-Pak (TO-252AA) package, supplied in bulk tube. The exposed drain pad on the bottom requires a copper land and thermal vias to the PCB ground plane — the 140 W power dissipation rating assumes the pad is soldered to a 1-inch-square copper area on a 2 oz board.