| 摘要 |
PURPOSE:To output a clock synchronously with a normal external clock of other system even when one system of the external clock is lost in the clock system using a VCO. CONSTITUTION:Clock units 1, 2 for systems 0, 1 are provided respectively with a VCO 12 and an OSC8 operated synchronously with external clocks a, b and stop outputs when the external clock of its own system only is lost, and when both external clocks a, b are lost, the OSC8 is selected. A clock selection unit 3 selects an output of the clock units 1, 2 and outputs the selected output and monitors the clock after the selection. |
