2SK3757 MOSFET — Specifications & Equivalents

About the 2SK3757

The 2SK3757 is an N-channel MOSFET with a drain–source voltage (V_DS) rating of 450 V, a continuous drain current (I_D) of 2 A and an on-resistance (R_DS(on)) of 2.45 Ω. It can dissipate up to 30 W and is rated to a junction temperature of 150 °C. It is supplied in the TO220SIS package.

At a glance

• Type: N-channel MOSFET
• Max drain–source voltage (V_DS): 450 V
• Max continuous drain current (I_D): 2 A
• On-resistance (R_DS(on)): 2.45 Ω
• Power dissipation (P_D): 30 W
• Max junction temperature (T_J): 150 °C
• Package: TO220SIS
• Manufacturer: Multi-source (JIS registered part number)

Typical applications

With its 450 V drain–source rating the 2SK3757 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.

On-resistance of 2.45 Ω is relatively high, so this part is better suited to low duty-cycle or low-current switching than to continuous high-current conduction.

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 a rise time of 15 ns and an output capacitance (C_oss) of 45 pF, which together with the gate drive determines switching loss and the practical upper frequency limit.

Choosing a replacement for the 2SK3757

A drop-in substitute for the 2SK3757 must be the same N-channel type and offer a drain–source rating of at least 450 V, a continuous drain current rating of at least 2 A and an on-resistance no higher than 2.45 Ω if efficiency and heat matter.

Mechanically, check the replacement against the TO220SIS footprint and confirm the pin order — parts sharing a package outline do not always share a pinout.

Because 2SK3757 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 2SK3757?

The 2SK3757 is an N-channel MOSFET (metal-oxide-semiconductor field-effect transistor). It is rated for 450 V drain-source and 2 A continuous drain current.

What is the maximum voltage of the 2SK3757?

The 2SK3757 has a maximum drain-source voltage (Vds) of 450 V. Treat this as an absolute maximum and design with margin, especially when switching inductive loads.

How much current can the 2SK3757 handle?

It is rated for 2 A of continuous drain current, with power dissipation limited to 30 W. Real-world capability depends on your heatsinking and ambient temperature.

What is the on-resistance of the 2SK3757?

On-resistance (Rds(on)) is 2.45 Ω. Multiply by the square of your load current to estimate conduction loss.

What package does the 2SK3757 come in?

It is listed in TO220SIS. Verify the pinout of the specific variant, as one outline can carry different pin assignments.

What can I use to replace the 2SK3757?

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.