Patent ID: 9018883
Filing Date: 2015-04-28
Classification: H02P

Abstract:
1. A motor drive circuit comprising: a first output terminal connected to a first end of a motor coil; a second output terminal connected to a second end of the motor coil; an H bridge circuit including: a first switch element having a first end connected to a power supply and a second end connected to the first output terminal, a second switch element having a first end connected to ground and a second end connected to the first output terminal, a third switch element having a first end connected to the power supply and a second end connected to the second output terminal, a fourth switch element having a first end connected to ground and a second end connected to the second output terminal, a PWM control circuit controlling the output current flowing into the motor coil by controlling the first to fourth switch elements; a signal control circuit that is supplied with first and second voltage signals from the first and second output terminals, and outputs the first voltage signal and the second voltage signal in accordance with an operating mode, wherein, in a first operating mode, the first voltage signal is output through a first signal terminal and power supply voltage is output through a second signal terminal; and, in a second operating mode, the power supply voltage is output through the first signal terminal and the second voltage signal is output through the second signal terminal; and an electric current detecting comparator that compares the signal output through the first signal terminal with a first reference voltage and supplies a comparison result signal to the PWM control circuit; and a zero point detecting comparator that compares the signal output through the second signal terminal with a second reference voltage and supplies a comparison result signal to the PWM control circuit, wherein the PWM control circuit controls the first to fourth switch elements based on the comparison result signals.