1N90 MOSFET — Specifications & Equivalents

About the 1N90

The 1N90 is a MOSFET with a drain–source voltage (V_DS) rating of 900 V and a continuous drain current (I_D) of 1 A. It can dissipate up to 40 W and is rated to a junction temperature of 150 °C. It is available in TO-220, TO-262, TO-251, TO-252, TO-220F and TO-220F1 packages, so confirm the pinout of the exact variant you order.

At a glance

• Type: MOSFET
• Max drain–source voltage (V_DS): 900 V
• Max continuous drain current (I_D): 1 A
• Power dissipation (P_D): 40 W
• Max junction temperature (T_J): 150 °C
• Package: TO-220, TO-262, TO-251, TO-252, TO-220F, TO-220F1

Typical applications

With its 900 V drain–source rating the 1N90 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.

At 1 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 ±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 22 pF, which together with the gate drive determines switching loss and the practical upper frequency limit.

Choosing a replacement for the 1N90

A drop-in substitute for the 1N90 should match its polarity and offer a drain–source rating of at least 900 V and a continuous drain current rating of at least 1 A.

Mechanically, check the replacement against the TO-220, TO-262, TO-251, TO-252, TO-220F and TO-220F1 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 1N90?

The 1N90 is a MOSFET (metal-oxide-semiconductor field-effect transistor). It is rated for 900 V drain-source and 1 A continuous drain current.

What is the maximum voltage of the 1N90?

The 1N90 has a maximum drain-source voltage (Vds) of 900 V. Treat this as an absolute maximum and design with margin, especially when switching inductive loads.

How much current can the 1N90 handle?

It is rated for 1 A of continuous drain current, with power dissipation limited to 40 W. Real-world capability depends on your heatsinking and ambient temperature.

What package does the 1N90 come in?

It is listed in TO-220, TO-262, TO-251, TO-252, TO-220F and TO-220F1. Verify the pinout of the specific variant, as one outline can carry different pin assignments.

What can I use to replace the 1N90?

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.