Motor control circuit, motor control integrated circuit, and method for controllably driving motor

A motor control circuit for supplying a drive voltage to a brushless direct current (DC) motor via a motor drive unit, the motor control circuit comprising:

• a current-zero point detector configured to detect a voltage corresponding to a drive current that flows through a coil of the brushless DC motor, and detect a timing at which the drive current becomes zero;
• a position-detecting signal generator configured to output a reference position detecting signal based on a Hall signal that is generated by a Hall element;
• a phase adjuster configured to adjust a phase of a targeted position detecting signal that is present after a subsequent cycle of the reference position detecting signal based on (i) the timing at which the drive current detected by the current-zero point detector becomes zero and (ii) the reference position detecting signal;
• and
• a drive controller configured to control a timing at which the drive voltage varies such that the timing of the drive voltage varying matches a timing at which the phase of the targeted position detecting signal changes, and to output the drive voltage,
• wherein the current-zero point detector is configured to be electrically coupled to the motor drive unit, and is configured to be electrically coupled to a first terminal of a resistor, a second terminal of the resistor being grounded,
• wherein the current-zero point detector is configured to detect a timing at which a level of a detected voltage corresponding to the drive current changes from either zero or a negative level to a positive level, to detect a zero point of the drive current,
• wherein the current-zero point detector is configured to receive two signals,
• wherein the current-zero point detector includes
• a voltage comparison circuit;
• a switch coupled to an input terminal of the voltage comparison circuit, and being configured to set an input voltage of the voltage comparison circuit to a voltage corresponding to the detected voltage or a ground voltage, based on an on-off status of each of the two signals;
• and
• a latching unit configured to output a state notification signal indicating a state of the drive current, based on a comparison result by the voltage comparison circuit,
• wherein the voltage comparison circuit includes
• a capacitor to which the input voltage is applied;
• an inverter coupled to a subsequent stage of the capacitor;
• and
• a switch configured to short-circuit the inverter according to a state of each of the two types of signals, during a time period in which the ground voltage is applied to the voltage comparison circuit, and
• wherein the voltage comparison circuit is configured to compare the ground voltage with the detected voltage, and output a comparison result.