Solenoid driver control circuit with initial boost voltage

A solenoid driver control circuit comprising:

• a control signal input terminal for receiving a control signal;
• current sense means for providing a current sense signal indicative of current flowing through a solenoid;
• solenoid driver means having a first operable state such that current can flow through said solenoid from a power source terminal and a second operable state lo such that current effectively cannot flow from said power source terminal through said solenoid;
• threshold comparator means for comparing at least one received reference threshold input signal with said current sense signal and for providing an output signal in response thereto to control said solenoid driver means and implement at least maximum limits for said solenoid current;
• pull-in current means for responding to said control signal by initially providing, for an initial pull-in period of time, at least a predetermined maximum first reference threshold to said comparator means corresponding to a maximum current limit for said solenoid current during said pull-in period of time;
• holding current means for providing, for a hold time after said pull-in period of time, at least a predetermined maximum second reference threshold to said comparator means corresponding to a maximum current limit for said solenoid current during said hold time, said hold maximum current limit being lower than said pull-in maximum current limit;
• battery circuit means for connection between a battery and said power source terminal to selectively provide a nominal voltage at said power source terminal;
• and
• boost means coupled to said power source terminal to selectively provide a boost voltage substantially in excess of said nominal voltage at said power source terminal;
• wherein the improvement comprises boost control means coupled to said boost means and said control terminal for providing, in response to said control signal, said boost voltage to said power source terminal during said pull-in period and for terminating providing said boost voltage at said power source terminal prior to termination of said pull-in time and at a predetermined time after boost voltage is applied to said power source terminal, said nominal voltage then being provided to said power source terminal during a remaining portion of said pull-in time.

A solenoid driver control circuit comprising:

• a control signal input terminal for receiving a control signal;
• current sense means for providing a current sense signal indicative of current flowing through a solenoid;
• solenoid driver means having a first operable state such that current can flow through said solenoid from a power source terminal at which voltage is applied and a second operable state such that current effectively cannot flow from said power source terminal through said solenoid;
• threshold comparator means for comparing at least one received reference threshold input signal with said current sense signal and for providing an output signal in response thereto to control said solenoid driver means and implement at least maximum limits for said solenoid current;
• pull-in current means for responding to said control signal by initially providing, for an initial predetermined pull-in period of time, at least a predetermined maximum first reference threshold to said comparator means corresponding to a maximum current limit for said solenoid current during said pull-in period of time;
• and
• holding current means for providing, for a hold time after said pull-in period of time, at least a predetermined maximum second reference threshold to said comparator means corresponding to a maximum current limit for said solenoid current during said hold time, said hold maximum current limit being lower than said pull-in maximum current limit;
• and
• wherein the improvement comprises control means coupled to said threshold comparator means for effectively extending said initial predetermined pull-in period of time in response to detecting failure of said sensed solenoid current to achieve said pull-in maximum current limit within a predetermined time after initiation of solenoid current flow during said pull-in period.