400 V N-channel in a compact SOT-223
The STMicroelectronics STN3N40K3 is an N-channel power MOSFET from the SuperMESH3™ series, rated for 400 V drain-source voltage and 1.8 A continuous drain current at case temperature. It comes in a surface-mount SOT-223 package (TO-261-4), making it a fit for space-constrained offline power supplies, auxiliary converters, and LED lighting drivers where board area is tight. The 3.4 Ohm maximum on-resistance at 600 mA and 10 V gate drive gives a reasonable conduction loss for a part this size. The 11 nC gate charge at 10 V means a small-signal MOSFET driver or a PWM controller output can switch it without a dedicated driver stage. Operating junction temperature spans -55°C to 150°C, so the part is at home in avionics, downhole instrumentation, or outdoor telecom gear where the ambient can swing wide. The 165 pF input capacitance at 50 V drain-source keeps switching losses moderate in the 50-150 kHz range typical of flyback converters.
Lifecycle and sourcing
The STN3N40K3 is listed as Active with ROHS3 compliance.