| 摘要 |
<p>PURPOSE:To prevent the consumption of the power supply of a system even if an IC card is connected to the system and at the same time a high potential is supplied to a signal terminal by providing a semiconductor switch which is turned on and electrified only when it is backed up by a battery in place of a pull-down resistance into the IC card. CONSTITUTION:A semiconductor switch 6 is turned on with the output signal of a power control circuit 1 in a battery back-up state, and the potential of a signal terminal 5 goes to a ground potential. Thus a CMOS semiconductor integrated circuit 2 which is backed up by a battery never internally consumes the useless power. Meanwhile the switch 6 is turned off with the output signal of the circuit 1 when an IC card is connected to a system. As a result, the system power supply is never consumed even if a high potential is set at the terminal 5.</p> |
