80 A continuous drain, 8.5 mΩ Rds(on) — what it means for a switching design
The STMicroelectronics STD65N55F3 is an N-channel STripFET power MOSFET rated for 55 V drain-source breakdown and 80 A continuous drain current at a 25°C case temperature.
The 175°C maximum junction is the ceiling; the 110 W power dissipation rating assumes the case is held at 25°C, so real-world derating curves from the datasheet are the reference for any design that runs the junction above 100°C. The 4 V maximum gate threshold at 250 µA drain current means the device turns on fully with a standard 10 V gate drive, but the threshold window is wide enough that logic-level drive at 5 V may not guarantee full enhancement across temperature.
DPAK footprint and sourcing
The STD65N55F3 comes in a surface-mount DPAK (TO-252-3) package with two leads and a tab that serves as the drain connection and primary thermal path.