| 摘要 |
PURPOSE:To reduce the thermal loss of a DC motor by PWM-controlling one of two semiconductor elements for deciding the rotating direction of the motor, and always holding the other element in a conductive state. CONSTITUTION:When a command signal level is higher than a threshold value V1, the output of a comparator 2 becomes an H level, and a transistor Q2 becomes a conductive state. At this time, a comparator 8 supplies the output of H level to a transistor Q3 only during a time when the command signal level is higher than that of a positive triangular wave output from a triangular wave generator 7. When a command signal level is lower than a threshold value -V2, the output of a comparator 3 becomes an H level to conduct a transistor Q1 and supplies the output of H level to a transistor Q4 only during a time when the command signal level is lower than the level of the negative triangular wave.
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