| 摘要 |
PURPOSE:To prevent generation of a drift and to reduce the cost by outputting a mute signal when the count of an up-down counter reaches the predetermined 1st value and interrupting the mute signal when the count reaches the predetermined 2nd value corresponding to the synchronous period. CONSTITUTION:When the count of an up-down counter at an asynchronous period reaches N, a signal starting the muting is outputted from a flip-flop circuit 15. Then after the mute signal is outputted, the mute signal is outputted until the count content of the up-down counter 14 subjected to down-count at the synchronous period agrees with 0, and the mute signal is interrupted when the content is coincident with 0. Even when the synchronous/asynchronous state takes place respectively in a short time, the muting is not applied excessive ly, noises on the acoustic feeling are reduced, and when the circuit is integrated, for example, generation of drift is prevented and the cost is reduced.
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