| 摘要 |
PROBLEM TO BE SOLVED: To prevent internal data from being destroyed when supply voltage is lowered by stopping the operation of a CPU when the supply voltage to an IC is lowered beyond a prescribed value and starting the operation of the CPU by an external reset signal. SOLUTION: When the supply voltage 5 to an IC card 4 is decreased, the CPU performs an abnormal operation such as a runaway, etc. Therefore, a voltage value slightly higher than the minimum operating voltage is set as the prescribed value of the supply voltage 5 in anticipation of safety. The prescribed value is always compared with the supply voltage 5 by a voltage reduction detecting means 1, and the supply voltage 5 is set in a monitored state during that time. When the fact that the supply voltage 5 is lowered beyond the prescribed value is detected by the voltage reduction detecting means 1, a voltage reduction signal is outputted to a CPU control means 2. The CPU control means 2 inputs the voltage reduction signal, and stops the operation of the CPU 3, and starts the operation of the CPU 3 by the external reset signal 7. In this way, the internal data is prevented from being destroyed. |
