Stepping motor drive device and method

摘要

A reference signal generation unit integrates a staircase signal, to produce reference signal VCTA whose waveform has no abrupt changes in level and which shows a current limit value. A PWM reference signal generation unit generates a PWM reference signal. A supply current measurement unit measures a supply current to a coil. A PWM control unit compares reference signal VCTA with the measurement value of the supply current measurement unit in each period of the PWM reference signal, and sets each transistor in a bridge rectification circuit in a conducting state or a nonconducting state according to the comparison result. In this way, the supply current to the coil is controlled to approach the current limit value shown by reference signal VCTA.