Reverse Bias Over-Current Protection for Power Field-Effect Transistors
Original Publication Date: 1986-Jul-01
Included in the Prior Art Database: 2005-Mar-09
This article describes a method for protecting a power field-effect transistor when the built-in parasitic diode is turned on. Power field-effect transistors (FETs) contain a built-in parasitic diode which is formed at the time of initial device fabrication. The diode is of opposite polarity relative to normal direction of current flow for which the device is designed. This article describes a method for protecting the FET when the parasitic diode is turned on. The circuitry disclosed herein is of significant use in power supply shunt regulator functions where there is a possibility of reverse bias currents feeding in through an output which can occur when multiple power supplies are used. It also has application where inductive loads (solenoids, relays, electric motors) are switched.