Motor drive circuit, motor drive method, and motor drive system

A motor drive system that controls a driving of a motor, comprising:

• a power source terminal to which a power source is connected between the power source terminal and a ground;
• a diode that has an anode connected to the power source terminal and a cathode connected to a power supply terminal;
• a smoothing capacitor that has one end connected to the cathode of the diode and the other end connected to the ground;
• a voltage scaling circuit that adjusts a voltage of the power source terminal and outputs a scaled voltage to a power source cutoff detection terminal;
• and
• a motor drive circuit that controls driving of the motor using power input from the power source via the power supply terminal to which the one end of the smoothing capacitor is connected, wherein the motor drive circuit comprises:
• a power source cutoff detection circuit that detects a voltage input through a power source cutoff detection terminal electrically connected to a power source terminal, detects that the power source has been cut off based on a detection result, and outputs a power source cutoff detection signal;
• a voltage detection circuit that detects the supply voltage of the power supply terminal, and
• outputs a voltage detection signal based on a detection result;
• a driver circuit that includes a first half bridge, a second half bridge, and a third half bridge connected in parallel between the power supply terminal and a ground terminal, the motor driver circuit supplying a drive current to the motor to rotate the motor, while the driver circuit controlling a coil current flowing through a coil of the motor to brake the motor;
• an overcurrent detection circuit that detects the coil current flowing through the coil of the motor through the driver circuit during a short-brake operation of the motor, detects that the coil current is equal to or greater than a preset threshold current, and outputs an overcurrent detection signal;
• and
• a control circuit that controls the operation of the motor by controlling the driver circuit based on the power source cutoff detection signal, the overcurrent detection signal, and the voltage detection signal.

A motor drive method that a drive of a motor is controlled by a motor drive circuit that uses power input from a power source through a power supply terminal to which one end of a smoothing capacitor is connected,

• wherein the motor drive circuit comprises:
• a power source cutoff detection circuit that detects a voltage input through a power source cutoff detection terminal electrically connected to a power source terminal, detects that the power source has been cut off based on a detection result, and outputs a power source cutoff detection signal;
• a voltage detection circuit that detects the supply voltage of the power supply terminal, and outputs a voltage detection signal based on a detection result;
• a driver circuit that includes a first half bridge, a second half bridge, and a third half bridge connected in parallel between the power supply terminal and a ground terminal, the motor driver circuit supplying a drive current to the motor to rotate the motor, while the driver circuit controlling a coil current flowing through a coil of the motor to brake the motor;
• an overcurrent detection circuit that detects the coil current flowing through the coil of the motor through the driver circuit during a short-brake operation of the motor, detects that the coil current is equal to or greater than a preset threshold current, and outputs an overcurrent detection signal;
• and
• a control circuit that controls the operation of the motor by controlling the driver circuit based on the power source cutoff detection signal, the overcurrent detection signal, and the voltage detection signal.