Patent ID: 8339092

Claim:
An integrated circuit having drive circuitry to drive the windings of a two phase stepper motor, the integrated circuit comprising means to make a measurement using the back electromotive force generated across the windings of the two phase stepper motor during the rotation of a rotor of the two phase stepper motor, wherein the measurement means comprises a two phase stepper motor driver circuit having a plurality of input/output terminals and a plurality of driver terminals, the two phase stepper motor driver circuit comprising first and second driver circuits for coupling to a first winding and third and fourth driver circuits for coupling to a second winding, wherein the first driver circuit has a first input/output terminal coupled for receiving a first signal and a first driver terminal for coupling to the first winding, the second driver circuit has a second input/output terminal coupled for receiving a second signal and a second driver terminal for coupling to the first winding, and wherein the third driver circuit has a third input/output terminal coupled for receiving a third signal and a third driver terminal for coupling to the second winding and the fourth driver circuit has a fourth input/output terminal coupled for receiving a fourth signal and a fourth driver terminal for coupling to the second winding, the measurement suitable for use as a two phase stepper motor control feedback signal, wherein the integrated circuit comprises: a first switch having a control terminal, a common terminal, and first and second conduction terminals; an amplifier having first and second inputs and an output, the first input of the amplifier coupled to the common terminal of the first switch; a second switch having a control terminal, a common terminal, and first and second conduction terminals, wherein the common terminal of the second switch is coupled to the second input of the amplifier; a third switch having a control terminal and first and second conduction terminals, the first conduction terminal coupled to the output of the amplifier; a first capacitor having first and second terminals, the first terminal coupled to the second conduction terminal of the third switch; and an output pin through which the two phase stepper motor control feedback signal is available as an analog output signal.