| 摘要 |
<p>PURPOSE:To prevent a fuse from being carelessly disconnected by impressing a cutting voltage to an input terminal and impressing a supply voltage to a terminal of an IC card when an input pulse is impressed to the input terminal. CONSTITUTION:An IC card power supply voltage (VDD) impressed to a terminal 18 at the time of operation turns on FETs 32, 26 and turns off a switching transistor(TR). When the VDD does not exist and voltage VPP is high, an FET 22 is on, so that an FET 24 is turned on. The FET 24 holds the gate of the switching TR 12 again at a potential level close to the earth level, so that the TR 12 is turned off. When the voltages VPP, VDD and an input pulse exist, FETs 23, 25 are connected, so that the FETs 24, 26 are turned off. When the VPP exists, an FET 31 is turned on and a voltage almost equal to the VPP is impressed to the gate of the TR 12. Thereby, the TR 12 is turned on, the VPP is impressed to the fuse 10 and the fuse 10 is disconnected.</p> |
