25N40A MOSFET — Specifications & Equivalents
About the 25N40A
The 25N40A is a MOSFET with a drain–source voltage (VDS) rating of 400 V and a continuous drain current (ID) of 25 A. It can dissipate up to 278 W and is rated to a junction temperature of 150 °C. It is supplied in the TO-3PN package.
At a glance
- Type: MOSFET
- Max drain–source voltage (VDS): 400 V
- Max continuous drain current (ID): 25 A
- Power dissipation (PD): 278 W
- Max junction temperature (TJ): 150 °C
- Package: TO-3PN
Typical applications
With its 400 V drain–source rating the 25N40A sits in the medium-high-voltage class of switching MOSFETs, typically found in telecom and industrial DC rails, boost and flyback converters, LED and backlight drivers and power-factor-correction stages. Common where the bus sits well above 100 V but below rectified mains.
Gate drive and switching notes
Keep gate–source voltage within the ±30 V maximum; exceeding it punctures the gate oxide and destroys the device permanently.
Switching behaviour is characterised by an output capacitance (Coss) of 390 pF, which together with the gate drive determines switching loss and the practical upper frequency limit.
Choosing a replacement for the 25N40A
A drop-in substitute for the 25N40A should match its polarity and offer a drain–source rating of at least 400 V and a continuous drain current rating of at least 25 A.
Mechanically, check the replacement against the TO-3PN footprint and confirm the pin order — parts sharing a package outline do not always share a pinout.
Where the application switches inductive loads or runs near the voltage limit, keep extra headroom rather than choosing a part that only just meets the original numbers.
Frequently asked questions
What is the 25N40A?
The 25N40A is a MOSFET (metal-oxide-semiconductor field-effect transistor). It is rated for 400 V drain-source and 25 A continuous drain current.
What is the maximum voltage of the 25N40A?
The 25N40A has a maximum drain-source voltage (Vds) of 400 V. Treat this as an absolute maximum and design with margin, especially when switching inductive loads.
How much current can the 25N40A handle?
It is rated for 25 A of continuous drain current, with power dissipation limited to 278 W. Real-world capability depends on your heatsinking and ambient temperature.
What package does the 25N40A come in?
It is listed in TO-3PN. Verify the pinout of the specific variant, as one outline can carry different pin assignments.
What can I use to replace the 25N40A?
This page lists 17 candidate equivalents matched on electrical ratings and package. Any replacement should meet or exceed the original voltage, current and dissipation figures and use a compatible drive level.
Key Specifications
| Pd ⓘ - Maximum Power Dissipation | 278 W |
|---|---|
| |Vds|ⓘ - Maximum Drain-Source Voltage | 400 V |
| |Vgs|ⓘ - Maximum Gate-Source Voltage | 30 V |
| |Id| ⓘ - Maximum Drain Current | 25 A |
| Tj ⓘ - Maximum Junction Temperature | 150 °C |
| Cossⓘ - Output Capacitance | 390 pF |
| Package | TO-3PN |
| INCHANGE Semiconductorisc N-Channel MOSFET Transistor 25N40AFEATURESDrain Current I = 25A@ T =25D CDrain Source Voltage | V = 400V(Min)DSSStatic Drain-Source On-Resistance: R = 0.2(Max)DS(on)Fast Switching100% avalanche testedMinimum Lot-to-Lot variations for robust device performanceand reliable operation.APPLICATIONSSwitch mode power suppl |
| SSH25N40AAdvanced Power MOSFETFEATURESBVDSS = 400 V Avalanche Rugged TechnologyRDS(on) = 0.2 Rugged Gate Oxide Technology Lower Input CapacitanceID = 25 A Improved Gate Charge Extended Safe Operating AreaTO-3P Lower Leakage Current | 10 A (Max.) @ VDS = 400V Low RDS(ON) : 0.162 (Typ.)1231.Gate 2. Drain 3. SourceAbsolute Maximum RatingsSymbol C |