A 6 A monolithic switch-mode solenoid driver

A monolithic intelligent-power switch-mode integrated circuit designed specifically for use as a solenoid driver is described. It uses pulsewidth modulation (PWM) techniques to provide a pull-in current of 6 A and a hold-in current of 3 A. The device has internal control, self-protection, and diagnostic capabilities. It uses a bipolar IC process with an isolated vertical PNP transistor option. The five interface pins are load and diagnostic outputs, the current supply (V/sub BATT/), and ground. In addition, a transistor-transistor-logic (TTL) level compatible input activates the device, and for the first 12 ms a high current is allowed to flow into the load from V/sub BATT/ to turn on the solenoid. The initial current is maintained in the range of 4 to 6 A using PWM of the high-side driver. Current rises in the inductive solenoid, and upon reaching 6 A the drive from V/sub BATT/ is removed. The recycle mode through the ground path is initiated, allowing the current to decay gradually to about 4 A, at which point the V/sub BATT/ drive is reapplied, and the cycle is repeated. Following this initial pull-in time, current thresholds are allowed to reduce, and the device switches between 2 and 3 A for the hold-in period.<>