800 V N-channel MOSFET for offline power conversion
The STF3LN80K5 is an 800 V N-channel power MOSFET from ST's MDmesh K5 series, built on a planar technology that balances on-resistance and switching losses for medium-power offline converters.
Gate drive and switching behaviour
Minimum gate threshold of 5 V at 100 µA drain current means the part is fully enhanced with a standard 10 V gate drive, but it will not turn on cleanly with 5 V logic-level signals — the recommended drive voltage for achieving the specified on-resistance is 10 V. Input capacitance measures 102 pF at 100 V drain-source, which keeps the Miller plateau short and supports clean switching edges in hard-switched topologies.
Thermal and package reality for the BOM
Maximum power dissipation is 20 W at case temperature, but the TO-220FP (Full Pack) isolates the back tab — that same plastic overmould limits thermal transfer to the heatsink compared to a standard TO-220 with a metal tab. For continuous operation above a few watts, a properly greased and clamped heatsink is mandatory, and the thermal resistance junction-to-case should be derated from the datasheet curve.
RoHS and REACH compliance is standard for this ST product family, consistent with the lead-free plating and halogen-free mould compound used in the TO-220FP package.