K2543-FP MOSFET — Specifications & Equivalents

About the K2543-FP

The K2543-FP is a MOSFET with a drain–source voltage (V_DS) rating of 650 V and a continuous drain current (I_D) of 12 A. It can dissipate up to 34 W and is rated to a junction temperature of 150 °C. It is supplied in the TO220FP package.

At a glance

• Type: MOSFET
• Max drain–source voltage (V_DS): 650 V
• Max continuous drain current (I_D): 12 A
• Power dissipation (P_D): 34 W
• Max junction temperature (T_J): 150 °C
• Package: TO220FP

Typical applications

With its 650 V drain–source rating the K2543-FP sits in the high-voltage (offline) class of switching MOSFETs, typically found in primary-side switching in offline SMPS (flyback, forward and quasi-resonant), active PFC boost stages, half-bridge and full-bridge inverters, induction heating and electronic ballasts and BLDC and AC motor drives. The rating leaves usable margin above the ~325 V DC bus obtained by rectifying 230 VAC mains, which is why this class dominates offline power supplies.

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 an output capacitance (C_oss) of 300 pF, which together with the gate drive determines switching loss and the practical upper frequency limit.

Choosing a replacement for the K2543-FP

A drop-in substitute for the K2543-FP should match its polarity and offer a drain–source rating of at least 650 V and a continuous drain current rating of at least 12 A.

Mechanically, check the replacement against the TO220FP footprint and confirm the pin order — parts sharing a package outline do not always share a pinout.

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 K2543-FP?

The K2543-FP is a MOSFET (metal-oxide-semiconductor field-effect transistor). It is rated for 650 V drain-source and 12 A continuous drain current.

What is the maximum voltage of the K2543-FP?

The K2543-FP has a maximum drain-source voltage (Vds) of 650 V. Treat this as an absolute maximum and design with margin, especially when switching inductive loads.

How much current can the K2543-FP handle?

It is rated for 12 A of continuous drain current, with power dissipation limited to 34 W. Real-world capability depends on your heatsinking and ambient temperature.

What package does the K2543-FP come in?

It is listed in TO220FP. Verify the pinout of the specific variant, as one outline can carry different pin assignments.

What can I use to replace the K2543-FP?

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.