| 摘要 |
<p>PURPOSE:To reduce the size of a circuit, the number of external parts and the number of terminal and to attain cost reduction by changing the operation speed of a CPU by one oscillation circuit. CONSTITUTION:The microcomputer consists of an oscillation circuit 1 using a crystal resonator, a CPU 2 and other peripheral circuit 3. The crystal control oscillation circuit 1 changes the capacity of a gate by switching the selection of a capacitor 11 with a small capacity and a capacitor 12 with a large capacity by a switching circuit 8 based upon a signal inputted from the CPU 2 to a control input terminal 10 to change an oscillation mode. Thereby, the operation speed of the CPU 2 can be switched by changing the frequency of a clock outputted from a clock signal output terminal to the CPU 2. Since the operation speed of the CPU 2 can be switched only by an oscillation circuit, the size of the circuit can be reduced, the number of external parts and the number of terminals can be also reduced and cost reduction can be attained.</p> |
