2SK3918 MOSFET — Specifications & Equivalents

About the 2SK3918

The 2SK3918 is an N-channel MOSFET with a drain–source voltage (V_DS) rating of 25 V, a continuous drain current (I_D) of 48 A and an on-resistance (R_DS(on)) of 0.0075 Ω. It can dissipate up to 29 W and is rated to a junction temperature of 150 °C. It is available in TO251 and TO252 packages, so confirm the pinout of the exact variant you order.

At a glance

• Type: N-channel MOSFET
• Max drain–source voltage (V_DS): 25 V
• Max continuous drain current (I_D): 48 A
• On-resistance (R_DS(on)): 0.0075 Ω
• Power dissipation (P_D): 29 W
• Max junction temperature (T_J): 150 °C
• Package: TO251, TO252
• Manufacturer: Multi-source (JIS registered part number)

Typical applications

With its 25 V drain–source rating the 2SK3918 sits in the very-low-voltage class of switching MOSFETs, typically found in battery protection and power-path switching, point-of-load converters and logic-level load switching in portable devices.

The low 0.0075 Ω on-resistance keeps conduction loss down, which suits synchronous rectification and continuous high-current paths.

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.

Total gate charge (Q_g) of 28 nC sets the drive current required: average gate current is roughly Q_g × switching frequency, so faster switching needs a stronger driver.

Switching behaviour is characterised by a rise time of 14 ns and an output capacitance (C_oss) of 310 pF, which together with the gate drive determines switching loss and the practical upper frequency limit.

Choosing a replacement for the 2SK3918

A drop-in substitute for the 2SK3918 must be the same N-channel type and offer a drain–source rating of at least 25 V, a continuous drain current rating of at least 48 A and an on-resistance no higher than 0.0075 Ω if efficiency and heat matter.

Mechanically, check the replacement against the TO251 and TO252 footprint and confirm the pin order — parts sharing a package outline do not always share a pinout.

Because 2SK3918 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 2SK3918?

The 2SK3918 is an N-channel MOSFET (metal-oxide-semiconductor field-effect transistor). It is rated for 25 V drain-source and 48 A continuous drain current.

What is the maximum voltage of the 2SK3918?

The 2SK3918 has a maximum drain-source voltage (Vds) of 25 V. Treat this as an absolute maximum and design with margin, especially when switching inductive loads.

How much current can the 2SK3918 handle?

It is rated for 48 A of continuous drain current, with power dissipation limited to 29 W. Real-world capability depends on your heatsinking and ambient temperature.

What is the on-resistance of the 2SK3918?

On-resistance (Rds(on)) is 0.0075 Ω. Multiply by the square of your load current to estimate conduction loss.

What package does the 2SK3918 come in?

It is listed in TO251 and TO252. Verify the pinout of the specific variant, as one outline can carry different pin assignments.

What can I use to replace the 2SK3918?

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.