| 摘要 |
In an IC card of dual-way type which is used in common as a non-contact/contact operation card, an isolation transistor is provided between a power supply voltage terminal and a contact power supply circuit. Non-contact/contact judging and switching unit 6 turns OFF, when it is detected that the IC card is operated in a non-contact operation mode, an isolation transistor to isolate between the power supply voltage terminal and contact power supply circuit. Accordingly, when the power supply voltage terminal is terminated with a ground terminal during the non-contact operation mode, erroneous operation of the IC card can surely be prevented. Since the power supply voltage terminal becomes equal to a reference potential in this case, monitoring of voltage of the power supply voltage terminal can be prevented and security of the IC card can also be improved remarkably.
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