| 摘要 |
PURPOSE:To easily attain frequency switching with simple constitution, by generating a sawtooth wave continuously with an input signal, and outputting a sawtooth wave signal when the repetitive number reaches a desired number. CONSTITUTION:When an FG signal is inputted via a wave shaping circuit 4, a pulse generating circuit 14 closes a gate circuit 16. In charging/discharging to a time constant circuit 15 at the same time, a sawtooth wave is repetitively outputted to a terminal voltage V1. The number of reqetitions is counted at a circuit 14 and when the number reaches a desired number, the circuit 16 is opened. As a result, the feedback path is closed and the voltage V1 increases up to the saturation voltage. The voltage V1 is outputted through the circuit 16 only when a gate signal G is H level to be a trapezoidal signal TRAP. When the control system is closed, a sampling pulse C comes to the center of slope of the signal TRAP. In switching the count value like this manner, the control frequency can easily and accurately be switched without the increase in externally mounted circuits. |
