| 摘要 |
PURPOSE:To use only one external control signal and to avoid the output control from being released simply by providing plural control signal detection circuits and a synthesis circuit synthesizing each control signal and outputting an output control signal and outputting a channel only able to detect the control signal. CONSTITUTION:Control signal detection circuits 3-6 detect a control signal of each channel from an inputted control signal. When the channel control signal is able to be detected, a high level is outputted to the same channel synchronized with an audio input signal subject to time division multiplex and when not able to be detected, a low level is outputted. Then an audio input signal is outputted as it is as the audio output signal when the output control signal A in the output control circuit 1 is at a high level and no output is outputted when the output control signal A is at a low level. Thus, one external control signal is enough and the output control cannot be released easily. |
