2021 MOSFET — Specifications & Equivalents

About the 2021

The 2021 is a MOSFET with a drain–source voltage (V_DS) rating of 20 V and a continuous drain current (I_D) of 0.55 A. It can dissipate up to 0.31 W and is rated to a junction temperature of 150 °C. It is supplied in the SOT323 package.

At a glance

• Type: MOSFET
• Max drain–source voltage (V_DS): 20 V
• Max continuous drain current (I_D): 0.55 A
• Power dissipation (P_D): 0.31 W
• Max junction temperature (T_J): 150 °C
• Package: SOT323

Typical applications

With its 20 V drain–source rating the 2021 sits in the very-low-voltage class of switching MOSFETs, typically found in battery protection and power-path switching, point-of-load converters and logic-level load switching in portable devices.

At 0.55 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 ±6 V maximum; exceeding it punctures the gate oxide and destroys the device permanently.

Choosing a replacement for the 2021

A drop-in substitute for the 2021 should match its polarity and offer a drain–source rating of at least 20 V and a continuous drain current rating of at least 0.55 A.

Mechanically, check the replacement against the SOT323 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 2021?

The 2021 is a MOSFET (metal-oxide-semiconductor field-effect transistor). It is rated for 20 V drain-source and 0.55 A continuous drain current.

What is the maximum voltage of the 2021?

The 2021 has a maximum drain-source voltage (Vds) of 20 V. Treat this as an absolute maximum and design with margin, especially when switching inductive loads.

How much current can the 2021 handle?

It is rated for 0.55 A of continuous drain current, with power dissipation limited to 0.31 W. Real-world capability depends on your heatsinking and ambient temperature.

What package does the 2021 come in?

It is listed in SOT323. Verify the pinout of the specific variant, as one outline can carry different pin assignments.

What can I use to replace the 2021?

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.