Current limited, thermally protected, power device

Abstract

A thermally protected power device is disclosed and includes a semiconductor package having at least five pins. One of the pins comprises a ground pin for connecting to a ground connection, and another one of the five pins comprises a power pin for connecting to a source of a temperature stable reference voltage. A field effect transistor is formed within the semiconductor package and has a source, drain and gate connected to three of the output pins and forms respective source, drain and gate pins. A parasitic bipolar transistor is formed within the package and has a base, collector and emitter. The collector is connected to the gate of the field effect transistor. A voltage divider circuit is formed within the semiconductor package and connected to the power pin, the ground pin and the base of the thermal limiting bipolar transistor for receiving a temperature stable reference voltage obtained from a temperature stable voltage source connected to the power pin, and dividing the voltage down close to the Vbe of the thermal limiting bipolar transistor. As the temperature rises within the semiconductor package, the Vbe of the thermal limiting bipolar transistor drops and switches on to pull gate voltage down and limit current passing through the field effect transistor.