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STMicroelectronics STN3N40K3

STN3N40K3 MOSFET, N-Channel 400V 1.8A SOT-223, Active

MPNSTN3N40K3
End of Life

STMicroelectronics SuperMESH3™ STN3N40K3, N-Channel MOSFET, 400V Vdss, 1.8A Id, 3.4Ohm Rds(on) @ 600mA/10V, SOT-223, -55°C to 150°C.

$0.85Ref. price · indicative, final on quote
STMicroelectronics STN3N40K3 datasheet (PDF)
PackagingTO-261-4, TO-261AA
RoHSROHS3 Compliant
SeriesSuperMESH3™
Independent supplier — new & surplus stockAuthenticity-screened · ESD-safe packingListing updated Jul 2026

Specifications

STN3N40K3 specifications
ParameterValue
SeriesSuperMESH3™
FET typeN-Channel
MountingSurface Mount
Drain to source voltage400 V
Drive voltage (Max rds on, min rds on)10V
Current - continuous drain (Id) @ 25°C1.8A (Tc)
Power dissipation3.3W (Ta)
Operating temperature-55°C ~ 150°C (TJ)
PackageTape & Reel (TR); Cut Tape (CT)
Vgs±30V
TechnologyMOSFET (Metal Oxide)
CaseTO-261-4, TO-261AA
Vgs(th) (Max) @ id4.5V @ 50µA
Rds on (Max) @ id, vgs3.4Ohm @ 600mA, 10V
Gate charge (Qg) (Max) @ vgs11 nC @ 10 V
Input capacitance (Ciss) (Max) @ vds165 pF @ 50 V

Product details

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.

Frequently asked questions

What are the specifications of STN3N40K3?

It is an N-channel MOSFET rated for 400 V drain-source voltage, 1.8 A continuous drain current at case temperature, 3.4 Ohm maximum on-resistance at 600 mA and 10 V gate drive, 11 nC gate charge at 10 V, and 165 pF input capacitance at 50 V. It operates from -55°C to 150°C junction temperature and comes in a SOT-223 package.

Can I use STN3N40K3 to replace a failed MOSFET in a power supply?

If the original MOSFET is an N-channel device rated for at least 400 V and 1.8 A in a SOT-223 or similar footprint, this part is a candidate. Verify the gate drive voltage — it needs 10 V to achieve the rated Rds(on). Also check the gate threshold (4.5 V max) and the pinout of the SOT-223 package against the original.