The STMicroelectronics STFILED524 is an N-Channel power MOSFET built with standard metal-oxide semiconductor technology.
The 525 V drain-source rating puts this MOSFET squarely into high-voltage offline applications — think flyback converters, PFC stages, or auxiliary supplies in industrial power systems. The 4 A continuous current at 25°C is the headline number, but real-world current depends on your switching frequency and heatsinking; the 20 W maximum power dissipation (Tc) is the hard ceiling. The 2.6 Ohm Rds(on) at 10 V gate drive is moderate — expect conduction losses around 2.6 W at 1 A, so plan for a heatsink or forced air if you run near the current limit. The through-hole I2PAKFP package is a field-service-friendly choice — no hot-air station needed, just a soldering iron and a screwdriver for the heatsink mount.