Current-Controlled Output Driver for Directly Coupled Loads

Driving loads such as electric motors, relay coils, and solenoids requires a relatively large initial pull-in or start-up current from a driver in order to initiate operation of the load. To maintain continuous operation, the hold or running operating current required for a load may be 20% or less of the initial pull-in or startup current. The problem is that a standard driver circuit acting as a switch continues to provide the same current throughout operation, wasting energy, and must be large enough to provide the large current continuously.