This circuit is basically switch mode current regulator with 2 modes (In-rush and Holding). In-rush current occurs in the first 64 ms of each on/off cycle with the rise time dependent on thecoil's resistance and inductance. The Hold-current is a partition of the In-rush current fixed by the ratio between V 1 and V2. A control pin is provided for enabling and disabling the gate control output for the external power MOS. The MOS transistor must be chosen according to the supply voltage range and the current flowing through the solenoid.