Patent ID: 6316902
Filing Date: 2001-11-13
Classification: H02P

Abstract:
A drive circuit for a step motor, comprising:switching means for passing electric current to the step motor, said switching means including a p-channel switching device and an n-channel switching device, for bipolar driving the step motor;phase signal generating means for generating a p-channel phase signal and an n-channel phase signal in accordance with driving pulse signals;driving means for generating a p-channel driving signal and an n-channel driving signal in accordance with the n-channel phase signal and the p-channel phase signal generated by said phase signal generating means, wherein the p-channel driving signal and the n-channel driving signal are applied to the p-channel switching device and the n-channel switching device, respectively;detecting means for detecting electric current flowing through the step motor; andpulse width modulating (PWM) means for generating a PWM signal based on the electric current detected by said detecting means,wherein the PWM signal is added to the n-channel phase signal and the p-channel phase signal, thereby controlling the electric current flowing through the step motor using the p-channel switching device and the n-channel switching device, so that the electric current is adjusted to a predetermined value.