| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a terminal for inputting an external clock while suppressing an increase in the number of terminals of a semiconductor device. <P>SOLUTION: A crystal oscillation circuit 2 produces an internal clock A3 based on a vibration frequency of a crystal oscillator X. An input terminal IN is input with a use information signal (an area A1a) showing use information of the external clock and an input signal A1 comprising the external clock (an area A1b). A memory circuit 3 retains and outputs the use information signal input in the input terminal, when a reset signal As is input in a reset terminal RST. A selection circuit 4 inputs the internal clock and the external clock input in the input terminal IN and outputs one of them according to the use information signal output from the memory circuit 3. This constitution can use the input terminal IN as the terminal for inputting the both of the external clock and the use information signal so as to suppress the increase in the number of the terminals. <P>COPYRIGHT: (C)2004,JPO</p> |
