Patent ID: 6055149
Filing Date: 2000-04-25
Classification: H01L,H03K

Abstract:
A thermally protected power device comprising:a semiconductor substrate;a field effect transistor formed on the semiconductor substrate and having a source, drain and gate;a voltage dropping resistor formed on the semiconductor substrate and connected to the gate of the field effect transistor;a thermal limiting bipolar transistor formed on the semiconductor substrate and having a base, collector and emitter, wherein the collector is connected to the voltage dropping resistor and gate of the field effect transistor; anda voltage divider circuit formed on the semiconductor substrate and having an output connected to the base of the thermal limiting bipolar transistor for receiving a temperature stable reference voltage from a temperature stable voltage source external to the semiconductor substrate and dividing the voltage down, wherein as the temperature rises within the semiconductor substrate, the Vbe of the thermal limiting bipolar transistor drops and switches on to pull the gate voltage down and limit current through the field effect transistor.