2SK3843 MOSFET — Specifications & Equivalents

About the 2SK3843

The 2SK3843 is an N-channel MOSFET with a drain–source voltage (V_DS) rating of 40 V, a continuous drain current (I_D) of 75 A and an on-resistance (R_DS(on)) of 0.0035 Ω. It can dissipate up to 125 W and is rated to a junction temperature of 150 °C. It is available in SC97 and TFP packages, so confirm the pinout of the exact variant you order.

At a glance

• Type: N-channel MOSFET
• Max drain–source voltage (V_DS): 40 V
• Max continuous drain current (I_D): 75 A
• On-resistance (R_DS(on)): 0.0035 Ω
• Power dissipation (P_D): 125 W
• Max junction temperature (T_J): 150 °C
• Package: SC97, TFP
• Manufacturer: Multi-source (JIS registered part number)

Typical applications

With its 40 V drain–source rating the 2SK3843 sits in the low-voltage class of switching MOSFETs, typically found in 12 V and 24 V automotive and industrial rails, synchronous buck converters, load switching and reverse-polarity protection and H-bridges for small motors.

The 75 A current rating puts it in high-current territory, where conduction loss (I² × R_DS(on)) and thermal design usually matter more than switching loss. Budget for adequate copper area and a heatsink.

The low 0.0035 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.

Switching behaviour is characterised by a rise time of 12 ns and an output capacitance (C_oss) of 1350 pF, which together with the gate drive determines switching loss and the practical upper frequency limit.

Choosing a replacement for the 2SK3843

A drop-in substitute for the 2SK3843 must be the same N-channel type and offer a drain–source rating of at least 40 V, a continuous drain current rating of at least 75 A and an on-resistance no higher than 0.0035 Ω if efficiency and heat matter.

Mechanically, check the replacement against the SC97 and TFP footprint and confirm the pin order — parts sharing a package outline do not always share a pinout.

Because 2SK3843 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 2SK3843?

The 2SK3843 is an N-channel MOSFET (metal-oxide-semiconductor field-effect transistor). It is rated for 40 V drain-source and 75 A continuous drain current.

What is the maximum voltage of the 2SK3843?

The 2SK3843 has a maximum drain-source voltage (Vds) of 40 V. Treat this as an absolute maximum and design with margin, especially when switching inductive loads.

How much current can the 2SK3843 handle?

It is rated for 75 A of continuous drain current, with power dissipation limited to 125 W. Real-world capability depends on your heatsinking and ambient temperature.

What is the on-resistance of the 2SK3843?

On-resistance (Rds(on)) is 0.0035 Ω. Multiply by the square of your load current to estimate conduction loss.

What package does the 2SK3843 come in?

It is listed in SC97 and TFP. Verify the pinout of the specific variant, as one outline can carry different pin assignments.

What can I use to replace the 2SK3843?

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.