600 V N-channel in a TO-220 — where it fits
The STP3NK60Z is a 600 V, 2.4 A N-channel MOSFET from ST's SuperMESH™ series, built in standard TO-220-3 through-hole. It targets offline switching applications — flyback converters, auxiliary power supplies, and PFC stages — where the 600 V drain-source rating provides adequate derating for universal-input rectified DC (up to 400 V nominal).
Gate charge and capacitance — switching efficiency
With a typical gate charge of 11.8 nC at 10 V and input capacitance of 311 pF at 25 V drain bias, this MOSFET is designed for moderate-frequency switching — think 60–100 kHz in a flyback or 40–70 kHz in a PFC boost. The low Qg means the gate driver sees a light reactive load, reducing driver losses and allowing smaller bootstrap capacitors. The Ciss figure also helps keep switching edges clean; expect dV/dt slew rates that are manageable without aggressive snubbing in a well-laid-out board.
The STP3NK60Z carries a lifecycle status of Not Recommended for New Design (NRND). There is no official L* successor listed in the record, so the replacement decision falls to parametric fit: a comparable 600 V N-channel with similar or lower Rds(on) and Qg, such as the STx3NK60Z family siblings, is the natural cross-shop.
The TO-220 package with its metal tab allows straightforward heatsinking — a simple clip-on or screw-mounted heatsink keeps the junction within limits at the 45 W maximum dissipation. Through-hole mounting suits point-to-point wiring on prototype boards or production runs where wave soldering is the primary assembly method.