Patent ID: 8569992

Claim:
A stepper motor controller for controlling one or more stepper motors, wherein the stepper motor controller has individual driver terminals and a common driver terminal, the stepper motor controller comprising: control circuitry having control outputs; individual driver pulse width modulation (PWM) circuitry having individual driver PWM outputs and modulation control inputs coupled to respective said control outputs; a group of individual drivers, each individual driver in the group having an individual driver input coupled to a respective one of the individual driver PWM outputs, and an individual driver output coupled to one of the individual driver terminals of the controller; common driver PWM circuitry having a common driver PWM output; and a common driver having a common driver input coupled to the common driver PWM output, and a common driver output coupled to the common driver terminal of the controller, wherein when one or more stepper motor field coils are connected between respective individual driver terminals and the common driver terminal, individual PWM driver currents are supplied to the stepper motor field coils from the individual driver terminals, and a common PWM driver current is supplied to the stepper motor field coils from the common driver terminal.