Driving Solenoid with current controlled PWM

[Rudolfo]

Interesting to see how a 5V coild can be used on 12V or 24V by using current controlled PWM rathern then normal valtage controlled one, or how to drive bistable relays, valves or lifting magnets in the application: Flexible and Low Power Driving of Solenoid Coils - http://ichaus.biz/wp8_whitepaper_en . 

[SL4P]

One technique used for both a rapid 'pull-in action' as well as saving power dissipation... is to drive the relay/coil/solenoid at rated voltage for some initial period - say 50ms - then drop back to the specified hold-in voltage (or equivalent PWM) as long as the PWM doesn't make the core resonate.  Turn the supply back to 0% to release.