Patent ID: 7863840
Filing Date: 2011-01-04
Classification: H02P

Abstract:
1. A motor driving circuit comprising: a synchronous rectification driving circuit configured to turn on and off a first source side transistor and a second sink side transistor as well as a second source side transistor and a first sink side transistor in a complementary manner, turn on and off the first and second sink side transistors based on a PWM signal, and turn on the first or second source side transistor kept in an off-state when the first or second sink side transistor is turned off by the PWM signal, to carry out synchronous rectification, when energizing a driving coil connected between a first connection point at which the first source side transistor and the first sink side transistor are connected in series and a second connection point at which the second source side transistor and the second sink side transistor are connected in series; a backflow detecting resistor connected to electrodes of the first and second sink side transistors, the electrodes being on an opposite side of the first and second sink side transistors to the first and second connection points; a backflow detecting comparator configured to output a comparison signal indicating a result of comparison between a voltage of a first terminal of the backflow detecting resistor and a voltage of a second terminal of the backflow detecting resistor, the first terminal being on a side of the electrodes and the second terminal being on an opposite side of the backflow detecting resistor to the first terminal; and a backflow prevention circuit configured to prohibit the synchronous rectification for a predetermined period when the comparison signal indicates that the voltage of the second terminal is higher than the voltage of the first terminal.