Motor-driving circuit and wire-bonding apparatus

A motor-driving circuit for driving a motor including;

• a rotor having a rotatable shaft with a permanent magnet attached thereto for generating magnetic flux;
• and
• a stator including an iron core, three-phase windings wound around their on core to form Y-connection windings, and three leads connected to and extending from the windings;
• said motor-driving circuit comprising:
• short-circuiting means for short-circuiting two of the three leads to each other;
• rotational position-detecting means for detecting a rotational position of the motor and outputting current position information;
• and
• control means for supplying an exciting current to the short-circuit leads and the remaining lead to control the shaft of the rotor to move to a designated rotational position within a narrow angular range, said exciting current having a value corresponding to a difference between the current position information from the rotational position-detecting means and externally input positional information which represents the designated rotational position within the narrow angular range.