What this N-channel STripFET III is and what it handles
The STMicroelectronics STD60N55F3 is a 55 V, 80 A N-channel power MOSFET from the STripFET™ III series, built with a planar stripe layout that keeps the on-resistance low at 8.5 mOhm maximum when driven with 10 V on the gate and 32 A through the drain. It's housed in the common DPAK (TO-252) surface-mount package, a three-lead tabbed part that solders down to a PCB pad with a decent thermal pour underneath to pull the heat out. The junction temperature range runs from -55°C to 175°C, so it's comfortable in engine-bay or industrial environments where the ambient climbs.
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Rework and layout notes for the DPAK
The DPAK (TO-252) is a rework-friendly package if you've got a hot-air station and a bit of practice. The tab also carries the drain current, so the solder joint there is both electrical and thermal.