SEMICONDUCTOR DEVICE AND IC CARD

摘要

In an IC card having an internal circuit LG1 operating from an internal power supply (VSS, VDD) formed of an external AC signal received through an antenna, voltage of the internal power supply may be varied through operation thereof. An inventive voltage control circuit REG comprises a voltage controlled current source VCCS, and a working current detection circuit PWR which detects a current larger than a specified current I1 flowing through the voltage controlled current source when the internal circuit is not operating and outputs an enable signal SIG1. When the internal circuit operates upon receiving the enable signal, a current component I1 being consumed in that internal circuit is reduced from a current flowing through the voltage controlled current source. Since variation of current in the internal power supply is prevented as a whole, output voltage thereof is held at a substantially constant level.