550 V, 8 A, 800 mOhm — what this MDmesh II MOSFET does
The STP8NM50: Its 550 V drain-source breakdown and 8 A continuous current rating place it in offline power supplies, PFC stages, flyback converters, and auxiliary bias rails.
ST officially lists the STP8NM50 as obsolete. It is no longer in production and has no direct successor published in ST's current portfolio.
Rds(on), gate charge, and the switching trade-off
At 8 A continuous drain (the 25°C case rating), the device dissipates over 50 W in conduction alone — that is half the 100 W package limit, so the TO-220 must be bolted to a heatsink with good thermal interface. Gate charge of 13 nC at 10 V is low for a 550 V part, which helps keep switching losses in check; the input capacitance of 415 pF at 25 V drain-source is consistent with a device optimised for moderate-frequency hard-switching rather than very-high-frequency resonant topologies. The ±30 V maximum gate-source rating gives margin for gate-drive overshoot in noisy environments.