Patent ID: 8330406

Claim:
A motor drive circuit comprising: a first power supply line and a second power supply line that are connected to a power supply, and a ground line that is not the first power supply line or the second power supply line; an H-bridge circuit comprising a first source transistor, a first sink transistor, a second source transistor and a second sink transistor, the first source transistor and the first sink transistor being connected in series, the second source transistor and the second sink transistor being connected in series, each of the first and second source transistors and the first and second sink transistors being connected to a corresponding regeneration diode, the first power supply line being connected to an input electrode of the first source transistor and an input electrode of the second source transistor, and a motor coil being connected between an output electrode of the first source transistor and an output electrode of the second source transistor; and a control circuit connected to the second power supply line and controlling the H-bridge circuit so that the first source transistor and the second sink transistor are turned on and off together so as to complement turning on and off of the second source transistor and the first sink transistor and so that the first and second source transistors are not turned on regardless of a voltage on the first power supply line when a voltage on the second power supply line is smaller than a predetermined voltage, wherein the second power supply line is connected to a current mirror circuit which is coupled to the first source transistor and the first sink transistor of the H-bridge.