APL501J [Microchip]

What is a Linear MOSFET?
A MOSFET specifically designed to be more robust than a standard MOSFET when operated with both high voltage and high current near DC conditions (>100 msecs).
The Problem with SMPS MOSFETs
MOSFETs optimized for high-frequency SMPS applications have poor high voltage DC SOA. Most SMPS-type MOSFETs overstate SOA capability at high voltage on the datasheets. Above ~30V and DC conditions, SOA drops faster than is indicated by Power Dissipation (PD) limited operation. For pulsed loads (t <10 ms), there is generally no problem using a standard MOSFET.
Technology Innovation
Introduced in 1999, Microchip modified its proprietary patented self-aligned metal gate MOSFET technology for enhanced performance in high voltage, linear applications. These linear MOSFETs typically provide 1.5–2.0 times the DC SOA capability at high voltage compared to other MOSFET technologies optimized for switching applications.

High Current and > 200 V > 100 msec

Used as a variable power resistor

Soft start application (limit surge currents)

Linear amplifier circuit

Active loads above 200 volts such as DC dynamic loads for testing power supplies, batteries, fuel cells, etc.

High voltage, high current constant current sources.