Thermal protection circuit for the die of a transistor

摘要

A thermal protection circuit for the die of a transistor having a heat sink in which a signal proportional to the dissipative input current and a signal proportional to the dissipative applied voltage of the transistor are multiplied to produce a signal representative of the applied power to the transistor. This representative applied power signal is transformed into a simulated differential in temperature between the die of the transistor and its heat sink. Simultaneously, the temperature of the heat sink is determined and this temperature is added to the simulated differential in temperature between the die of the transistor and the heat sink to determine a sensed die temperature. A control responsive to this sensed die temperature reduces the applied power to the transistor.