INDUCTIVE LOAD DRIVER PROTECTION CIRCUITS HAVING MINIMAL POWER DISSIPATION

摘要

A driver circuit for inductive loads is desired which is capable of delivering large amounts of average current but has only minimal power dissipation requirements, is self-protecting and suitable for being embodied in monolithic integrated form. The driver circuit includes an output transistor (58) having an emitter coupled to a current sensor (60) and a collector adapted to be coupled to the electrical load (56). A comparator (72) senses the magnitude of a current sensor signal and applies trigger signals to a time delay circuit (82) which is connected between the output of the comparator (80) and the control terminal (87) of a control circuit for the protected transistor (58). The rise time of the voltage across the current sensor (60) depends on the inductance, for instance, of the load (56). The time delay circuit (82) enables the control circuit to disable the output transistor (58) for a predetermined time duration in response to the threshold voltage of the comparator (72) being exceeded by the sensor voltage. At other times, the protected transistor (58) is saturated by the control circuit so that power is delivered to the load. The driver circuit is useful in automotive applications.