2SK944 MOSFET — Specifications & Equivalents
Manufacturer: Multi-source (JIS registered part number)
About the 2SK944
The 2SK944 is an N-channel MOSFET with a drain–source voltage (VDS) rating of 250 V, a continuous drain current (ID) of 22 A and an on-resistance (RDS(on)) of 0.15 Ω. It can dissipate up to 150 W and is rated to a junction temperature of 150 °C. It is supplied in the TO3PN package.
At a glance
- Type: N-channel MOSFET
- Max drain–source voltage (VDS): 250 V
- Max continuous drain current (ID): 22 A
- On-resistance (RDS(on)): 0.15 Ω
- Power dissipation (PD): 150 W
- Max junction temperature (TJ): 150 °C
- Package: TO3PN
- Manufacturer: Multi-source (JIS registered part number)
Typical applications
With its 250 V drain–source rating the 2SK944 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 ±20 V maximum; exceeding it punctures the gate oxide and destroys the device permanently.
Switching behaviour is characterised by a rise time of 25 ns and an output capacitance (Coss) of 800 pF, which together with the gate drive determines switching loss and the practical upper frequency limit.
Choosing a replacement for the 2SK944
A drop-in substitute for the 2SK944 must be the same N-channel type and offer a drain–source rating of at least 250 V, a continuous drain current rating of at least 22 A and an on-resistance no higher than 0.15 Ω if efficiency and heat matter.
Mechanically, check the replacement against the TO3PN footprint and confirm the pin order — parts sharing a package outline do not always share a pinout.
Because 2SK944 is a JIS-registered part number rather than one vendor's proprietary series, it is produced by several manufacturers. Datasheet figures vary slightly between them, so check the datasheet of the brand you actually buy — this also makes like-for-like sourcing easier.
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 2SK944?
The 2SK944 is an N-channel MOSFET (metal-oxide-semiconductor field-effect transistor). It is rated for 250 V drain-source and 22 A continuous drain current.
What is the maximum voltage of the 2SK944?
The 2SK944 has a maximum drain-source voltage (Vds) of 250 V. Treat this as an absolute maximum and design with margin, especially when switching inductive loads.
How much current can the 2SK944 handle?
It is rated for 22 A of continuous drain current, with power dissipation limited to 150 W. Real-world capability depends on your heatsinking and ambient temperature.
What is the on-resistance of the 2SK944?
On-resistance (Rds(on)) is 0.15 Ω. Multiply by the square of your load current to estimate conduction loss.
What package does the 2SK944 come in?
It is listed in TO3PN. Verify the pinout of the specific variant, as one outline can carry different pin assignments.
What can I use to replace the 2SK944?
No verified equivalents are listed yet. Choose a part of the same polarity that meets or exceeds every rating above and shares a compatible package and pinout.
Key Specifications
| Type | MOSFET |
|---|---|
| Channel Type | N -Channel |
| Drain-Source Voltage (Vds) | 250 V |
| Gate-Source Voltage (Vgs) | 20 V |
| Drain Current (Id) | 22 A |
| Drain-Source On-Resistance (Rds) | 0.15 |
| Rise Time (tr) | 25 nS |
| Output Capacitance (Coss) | 800 pF |
| Junction Temperature (Tj) | 150 °C |
| Package | TO3PN |
| Power Dissipation (Pd) | 150 W |
Equivalent & Replacement Parts
No verified equivalents are listed for 2SK944 yet.