Patent ID: 7843674
Filing Date: 2010-11-30
Classification: H02H,H02M,H02P

Abstract:
1. A motor drive circuit comprising: a current passage control circuit configured to perform ON/OFF control of a drive transistor connected to a motor coil to pass current through the motor coil; an overcurrent state detection circuit configured to detect whether or not current passing through the drive transistor is in an overcurrent state where the current exceeds a predetermined threshold value; a charging and discharging circuit configured to start charging a capacitor in response to detecting the overcurrent state by the overcurrent state detection circuit and subsequently discharge the capacitor in response to not detecting the overcurrent state; and an overcurrent protection control circuit configured to stop the ON/OFF control of the drive transistor performed by the current passage control circuit to turn off the drive transistor, for an elapsed charging period for a charging voltage of the capacitor at a predetermined voltage to exceed a threshold voltage, and determine whether or not to perform such an overcurrent protection control as to turn off the drive transistor by detection of the overcurrent state, after the charging period has elapsed.