| 摘要 |
PROBLEM TO BE SOLVED: To suppress the vibration noise of a motor and the drive efficiency from lowering. SOLUTION: When a voltage V2 is between voltage values V4 and V5, a comparator 17 compares a sawtooth signal C with a reference voltage V2. When the ambient temperature rises and the voltage V2 drops below the voltage V4, the comparator 17 compares the sawtooth signal C with a reference voltage V4. The reference voltage V4 limits the contraction width of a first comparison signal D to an interval T3, and since the end and start of driving currents IL1, IL2 can be prevented for overlapping, drive efficiency of motor can be prevented from lowering. When the ambient temperature decreases and the voltage V2 becomes higher than the voltage V5, the comparator 17 compares a sawtooth signal C with a reference voltage V5. By setting the reference voltage V5 is set at a value for rotating the motor, the motor can be rotated at a speed corresponding to the ambient temperature at all times. The motor drive circuit can be provided as a one chip integrated circuit. |
