INDUCTIVE LOAD DRIVER CIRCUIT EFFECTING SLOW HOLD CURRENT DECAY AND FAST TURN OFF CURRENT DECAY

摘要

ABSTRACTAn inductive load driver circuit comprising firstand second switch means and high and low impedance loadcurrent decay means. For the duration of a load actuationsignal the first switch means are responsive to themagnitude of the load current to complete and interrupta first current path to the load to cycle the load currentbetween first and second levels. The second switchmeans are enabled for the duration of the load actuationsignal to complete a second current path to the loadwhen the first switch means interrupts the first currentpath. When completed the second current path comprisesthe low impedance decay means allowing the load currentto decay slowly from the first current level to the secondlevel to provide during such slow decay a load currentsufficient to maintain actuation of the inductive load.The end of the load actuation signal disables the secondswitch means to interrupt the second current path andthereby require the load current to decay rapidly throughthe high impedance decay means. In one embodiment,the second switch means comprise an SCR disabled bya final momentarily turn ON of the first switch means.