2N4003K MOSFET — Specifications & Equivalents

About the 2N4003K

The 2N4003K is a MOSFET with a drain–source voltage (V_DS) rating of 30 V and a continuous drain current (I_D) of 0.5 A. It can dissipate up to 0.69 W and is rated to a junction temperature of 150 °C. It is supplied in the SOT23 package.

At a glance

• Type: MOSFET
• Max drain–source voltage (V_DS): 30 V
• Max continuous drain current (I_D): 0.5 A
• Power dissipation (P_D): 0.69 W
• Max junction temperature (T_J): 150 °C
• Package: SOT23
• Manufacturer: Multi-source (JEDEC registered part number)

Typical applications

With its 30 V drain–source rating the 2N4003K 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.

At 0.5 A it is aimed at small-signal and light-load switching rather than power conversion.

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 an output capacitance (C_oss) of 19.7 pF, which together with the gate drive determines switching loss and the practical upper frequency limit.

Choosing a replacement for the 2N4003K

A drop-in substitute for the 2N4003K should match its polarity and offer a drain–source rating of at least 30 V and a continuous drain current rating of at least 0.5 A.

Mechanically, check the replacement against the SOT23 footprint and confirm the pin order — parts sharing a package outline do not always share a pinout.

Because 2N4003K is a JEDEC-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 2N4003K?

The 2N4003K is a MOSFET (metal-oxide-semiconductor field-effect transistor). It is rated for 30 V drain-source and 0.5 A continuous drain current.

What is the maximum voltage of the 2N4003K?

The 2N4003K has a maximum drain-source voltage (Vds) of 30 V. Treat this as an absolute maximum and design with margin, especially when switching inductive loads.

How much current can the 2N4003K handle?

It is rated for 0.5 A of continuous drain current, with power dissipation limited to 0.69 W. Real-world capability depends on your heatsinking and ambient temperature.

What package does the 2N4003K come in?

It is listed in SOT23. Verify the pinout of the specific variant, as one outline can carry different pin assignments.

What can I use to replace the 2N4003K?

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.