800 V N-channel MOSFET for offline power stages
It is built with ST's MDmesh™ technology, a multi-drain mesh layout that reduces on-resistance per unit area for high-voltage switching. The TO-251 (IPAK) through-hole package saves board height compared to a full TO-220, making it a fit for compact PSU modules and adapter designs where vertical clearance is tight.
If a pin-compatible drop-in replacement is needed, the STP7NM80 (same die in a TO-220 package) is a common cross-shop candidate, though the package difference (TO-220 vs TO-251) changes the board footprint and thermal interface. No official ST successor order code is listed for the TO-251 variant.
Key ratings that drive the selection
The 800 V Vdss rating is the headline spec — it allows the MOSFET to block the rectified DC bus in universal-input offline supplies (up to 400 V nominal) with healthy margin for switching transients. The 1.05 Ohm Rds(on) at 10 V gate drive means conduction losses will be noticeable at currents above 2 A; for a 6.5 A rated device, the actual operating point in a typical flyback will be 1–3 A, where the dissipation is manageable with the TO-251's junction-to-case thermal resistance. Gate charge is 18 nC at 10 V, a moderate figure that keeps driver losses low in high-frequency switching (60–100 kHz range). Input capacitance is 620 pF at 25 V drain-source, which is low enough that the gate drive power requirement is modest — a benefit in self-biased or low-power controller designs.