Semiconductor integrated circuit device and IC card equipped with the same having transistor switch for disconnecting contact power during contactless mode

摘要

There is a need for turning off a transistor in a power supply switch circuit irrespective of relative potential relationship between a contact power supply terminal and an internal power supply line and making it possible to decrease an on-resistance of an MOS transistor without increasing the size of the MOS transistor constituting the power supply switch circuit. The power supply switch circuit is comprised of two PMOS transistors whose gate terminals connect with two pull-up circuits. A charge pump circuit generates a negative voltage and is connected to a pull-down circuit. The pull-down circuit is connected to the gate terminals in common. During a contactless operation, the pull-up circuit short-circuits one gate terminal to a contact power supply terminal VDD and the other gate terminal to an internal power supply line VDDA. During a contact operation, the pull-up circuit supplies both gate terminals with a negative voltage from the charge pump circuit.