| 摘要 |
PURPOSE: To provide the clock generating device which selects a clock generating circuit in an oscillation state out of plural clock generating circuits at the time of actuation, and evades a defect in the operation of a system due to an oscillation defect, etc., and supplies a clock safely. CONSTITUTION: This clock generating device has plural clock detecting means 16 and 20 which includes plural clock generating circuits 1 and 2, counters 13 and 17, and storage means 15 and 19, and input clocks from the clock generating circuits 1 and 2 and output select signals 27 and 28 when a predetermined count value is reached, a selecting means 12 which selectively outputs the clocks 3 and 4 outputted from the clock generating circuits 1 and 2 on the basis of the select signals 27 and 28 outputted from the clock detecting means 16 and 20, and a control circuit 10 which stops the oscillation detecting operation of the clock detecting means 16 or 20 on the basis of the select signal that is outputted first. |
