STF11N65K3 MOSFET — Specifications & Equivalents

About the STF11N65K3

The STF11N65K3 is a MOSFET with a drain–source voltage (V_DS) rating of 650 V and a continuous drain current (I_D) of 11 A. It can dissipate up to 35 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): 11 A
• Power dissipation (P_D): 35 W
• Max junction temperature (T_J): 150 °C
• Package: TO220FP
• Manufacturer: Commonly produced by STMicroelectronics

Typical applications

With its 650 V drain–source rating the STF11N65K3 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 125 pF, which together with the gate drive determines switching loss and the practical upper frequency limit.

Choosing a replacement for the STF11N65K3

A drop-in substitute for the STF11N65K3 should match its polarity and offer a drain–source rating of at least 650 V and a continuous drain current rating of at least 11 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 STF11N65K3?

The STF11N65K3 is a MOSFET (metal-oxide-semiconductor field-effect transistor). It is rated for 650 V drain-source and 11 A continuous drain current.

What is the maximum voltage of the STF11N65K3?

The STF11N65K3 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 STF11N65K3 handle?

It is rated for 11 A of continuous drain current, with power dissipation limited to 35 W. Real-world capability depends on your heatsinking and ambient temperature.

What package does the STF11N65K3 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 STF11N65K3?

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.