| 摘要 |
<p>PURPOSE:To prevent a microcomputer from generating malfunction by stopping the operation of the microcomputer only for a sufficient long period for normally operating the microcomputer without using a switched oscillation clock when a 1st or 2nd oscillation clock is switched. CONSTITUTION:A switching circuit 1 switches and outputs an oscillation clock (a) outputted from an oscillation circuit A or an oscillation clock (b) outputted from an oscillation circuit B. At the time of switching the oscillation clock (a) or (b), a trigger circuit 6 to which an oscillation clock selecting signal SE LECT is added generates a trigger signal (d). The passage of an output from the circuit 1 through a gate circuit 5 is inhibited by the trigger signal or permitted by the output of the circuit 1 and the detecting result of a detecting circuit 7 and the microcomputer is driven based upon the output of the gate circuit 5. Consequently, the microcomputer can be prevented from generating malfunction.</p> |
