55 V, 20 A automotive N-channel HEXFET — what the ratings mean for the BOM
The Infineon AUIRFR4105 is an automotive-grade N-channel HEXFET MOSFET rated for 55 V drain-source breakdown and 20 A continuous switching current. It is built on the HEXFET trench technology, delivering a maximum on-resistance of 45 mOhm at 16 A with a 10 V gate drive — the operating point you will design around for a motor-drive output stage, a DC-DC converter primary switch, or a high-side load switch in an automotive ECU. The 34 nC total gate charge at 10 V keeps switching losses moderate for a 20 A device; a standard automotive gate driver IC (e.g., the AUIRS212x family) handles the drive without excessive cross-conduction delay.
Junction temperature range — under-hood and high-side capability
Junction temperature range is -55°C to 175°C. Power dissipation is 68 W.
Gate drive voltage — ±20 V Vgs rating
Maximum gate-source voltage is ±20 V. Threshold voltage is 4 V at 250 µA.
Package and mounting — surface-mount D-Pak
Surface-mount package (D-Pak / TO-252) suited for automated assembly on an automotive PCB. The tab is the drain terminal; ensure the copper footprint and thermal vias are sized for the 68 W dissipation if the part runs near its current limit.
Lifecycle and sourcing — active production, no LTB risk
The AUIRFR4105 carries an Active lifecycle status from Infineon. It remains a valid BOM line for new designs and production builds with no last-time-buy window in effect.