Patent ID: 6479954
Filing Date: 2002-11-12
Classification: G11B,H02P,H03F

Abstract:
A system for controlling and driving an actuator comprising:a current sensing resistance to be connected in series with the actuator; a pair of power stages connected to said current sensing resistance and to the actuator for driving the actuator in a bridge configuration; an operational amplifier for monitoring current forced in a winding of the actuator; and a control circuit connected between an output of said operational amplifier and said pair of power stages; said operational amplifier comprising a first differential input stage having a noninverting input coupled to a reference voltage and an inverting input coupled to the output of said operational amplifier for forming a transconductance feedback loop, and a second differential input stage connected in parallel to said first differential input stage and having a noninverting input and an inverting input respectively switchable between terminals of said current sensing resistance during a driving phase, and outputs of said pair of power stages during a phase of momentary interruption of the driving for sensing a zero-crossing of the back electromotive force (BEMF).