The through-hole TO-220-3 package makes it a practical choice for power supplies, DC-DC converters, motor drives, and automotive load switching where you need to bolt it to a heatsink and run wires.
Key ratings for the BOM decision
The 30 V drain-source rating means this part lives in the low-voltage domain — 12 V and 24 V buses, battery circuits, point-of-load regulators. It is not for 48 V or higher rails. The 45 A continuous current is the headline number at 25°C case; real-world current is derated by the thermal curve, and the 70 W power dissipation limit is the practical ceiling with adequate heatsinking. The part also specifies drive at 4.5 V for logic-level gate signals, but the on-resistance will be higher — check the typical curve. Gate charge is 17 nC at 5 V, which keeps switching losses manageable for moderate-frequency PWM. That 175°C max junction is higher than many logic-level MOSFETs, giving thermal headroom if you are running near the current limit in a hot enclosure.
The STP45NF3LL is listed as obsolete. No last-time-buy window exists; this is strictly a broker-channel part now.
Field-service note: the TO-220 is your friend
The TO-220-3 through-hole package is a field-service win. No hot-air station needed — a soldering iron and a desoldering pump or wick gets it swapped on site. The tab is the drain, so orientation is straightforward with the pinout from the datasheet.