| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a card detection circuit capable of detecting the insertion of a card by means of a simple circuit arrangement, while decreasing the current consumed during the detection. <P>SOLUTION: A switch closes upon the insertion of a card into a card socket 2 and the level of a level signal 101 of an L1 terminal varies from high (H) to low (L) level. The card detection circuit includes an insertion detection circuit 12 which outputs a pulsed insertion signal 102 when the level of the level signal varies; a holding circuit 13 which receives the input of the insertion signal 102 and outputs a switching signal 103 of (L) level self-held on the output side thereof; and a switch 15 which releases the ground of an L2 terminal when the switching signal 103 becomes (L). A reset pulse 106 is inputted from the outside and the switching signal 103 held in the holding circuit 13 is temporarily restored to (H). Upon removal of the card, the self-holding is automatically released to return to the initial state. During insertion of the card a current flowing in a pull-up resistance 11 is eliminated. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
