Motor drive circuit and motor drive system using the circuit thereof

A motor drive system, comprising,

• a Hall element for determining the phase of the rotor in a single phase DC motor;
• the single phase DC motor;
• a motor drive circuit including an amplifier which receives output signals of said Hall element and outputs the same after amplification,
• a drive signal generating circuit which receives the amplified signals of said amplifier, generates first and second pulses each having a duty of about 50% of which phases differ by about 180.degree. and outputs the same,
• a first drive circuit connected to a first terminal of said single phase DC motor, and
• a second drive circuit connected to a second terminal of said single phase DC motor;
• said first and second drive circuits each including a first transistor circuit which supplies a current to said single phase DC motor,
• a second transistor circuit which sinks a current from said single phase DC motor, and
• a diode which bypasses a current flown out from said single phase Dc motor toward a power source line side, whereby said first and second drive circuits alternately serve as a current flow out side and as a current sink side in response to the first and second pulses to drive said single phase DC motor;
• and
• wherein said amplifier, said drive signal generating circuit and said first and second drive circuits are integrated into one IC, the bypassing diodes toward the power source line side being respectively inserted between the first terminal and the power source line and between the second terminal and the power source line, and the combination thereof being mounted on an electric device.