| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide an integrated circuit which can detect the light irradiated for the purpose of unauthorized use more certainly than the conventional semiconductor integrated circuit in order to limit the operation of a protected circuit. <P>SOLUTION: The integrated circuit includes a first photo diode 1 which is arranged in parallel with and inversely connected to a first protected circuit, and is so configured as to limit the operation of the first protected circuit according to the cathode potential of the first photo diode 1. The integrated circuit comprises a first electric resistance 3 with one end connected to the cathode of the first photo diode and the other end connected to the power supply potential side; a first Schmitt circuit which has a first threshold voltage and a second threshold voltage higher than the first one for a falling and a rising cathode potential, respectively, and outputs a predetermined potential when the falling cathode potential is lower than the first threshold voltage or the rising cathode potential is lower than the second threshold voltage; and a control circuit which limits the operation of the first protected circuit when the first Schmitt circuit 2 outputs the predetermined potential. <P>COPYRIGHT: (C)2007,JPO&INPIT</p> |
