| 摘要 |
<P>PROBLEM TO BE SOLVED: To self-oscillate at a required frequency by using a data string divided for every fixed cycle by a SOF (Start of Frame) packet or the like without using a vibrator. <P>SOLUTION: A semiconductor integrated circuit has an external interface circuit, and the external interface circuit has a clock generation circuit (100) which inputs and outputs the data string divided for every fixed cycle and generates a synchronizing clock signal for use in synchronization of data input/output. The clock generation circuit has a self-oscillation circuit (120) being the oscillation source of the synchronizing clock signal and a control circuit (110) for finely adjusting the oscillation frequency of the self-oscillation circuit, and the control circuit detects delimitations of the fixed cycle in the data string and measures intervals of delimitations on the basis of the oscillation output of the self-oscillation circuit and controls the oscillation output of the self-oscillation circuit in such a direction that a measured value coincides with a target value. Thus self-oscillation at a required frequency is made possible by using a data string divided for every fixed cycle by the SOF packet or the like without using a vibrator. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
