Integrierte Schaltung und Methode zur programmierten Thermalabschaltung für Starkstromgeräte

A thermal control circuit for an integrated power transistor comprises a current generator, controlled by a turn on signal, a sensing resistance in series to the power transistor, a current limiter acting when the voltage drop on the sensing resistance overcomes a certain value, a current amplifier coupled to the output node of the controlled current generator, outputting a drive current that is injected on a control node of the power transistor, and a soft thermal shut down circuit whose conduction state is enhanced as the temperature increases for reducing the drive current. The circuit controls the voltage on the power transistor in a more effective manner than known devices because the current amplifier has a variable gain controlled by the state of conduction of the soft thermal shut down circuit. The improvement substantially consists in reducing progressively the gain of the current amplifier as the temperature of the integrated circuit increases, until a thermal equilibrium is reached.