| 摘要 |
PURPOSE:To suppress influences to data processing in a device when the clock of a system designated by a system selecting signal is set to a discontinued state, by performing autonomous system switching and, at the same time, outputting signals indicating the autonomous switching for a fixed time. CONSTITUTION:Data, frame pulses, and clocks of two systems are respectively received and either system of them is selected in accordance with the designation of system selecting signals inputted from the outside. When it is detected that the clock of the system designated by the system selecting signals becomes to a discontinued state in accordance with the output signals of clock discontinuation monitoring circuits 2 and 3 which monitor the discontinued states of the clocks of two systems and the system selecting signals at the time of clock selection, autonomous switching is performed by sending instruction signals for selecting the data, frame pulse, and clock of another system and, at the same time, signals indicating that the autonomous switching is performed are outputted for a fixed time. Therefore, bad influences to data processing in a device can be prevented.
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