Patent ID: 6879128

Claim:
A motor driver circuit comprising: An H-switch circuit arranged for connection with each phase of a multi-phase step motor; a switch driver interconnected with said H-switch and a bridge control circuit; a set point generator connecting with said bridge control circuit and said H-switch circuit for removal of excess phase current from said multi-phase step motor; a step input to said set point generator for providing a set point current value to said set point generator; a pair of operational amplifiers and a pair of comparators interconnected together and with said bridge control circuit, said operational amplifiers being connected with said H-switch in feed back circuit arrangement; a phase current sensing resistor connecting with inputs to said operational amplifiers for providing a sensing current value to said operational amplifiers; an output of one of said comparators connects with said bridge control circuit to provide a forward current to said bridge control circuit and; an output of another of said comparators connects with said bridge control circuit to provide a reverse current to said bridge control circuit; whereby current in each phase of said multi-phase step motor is monitored and excess current above said set point current value is reduced thereby bringing current in said each phase down to said set point current value.