Power line connection circuit and power line switch IC for the same

Claim 1

A power line connection circuit for controlling a connection of a power supply line to a load circuit, comprising: a MOS transistor connecting said power supply line to said load circuit, the conductance of said MOS transistor being changeable by applying a signal to a gate of said MOS transistor; voltage conversion means for converting a voltage of said power supply line and applying the converted voltage to said gate of said MOS transistor; and clamp means for limiting, and simultaneously, for allowing said converted voltage output from said voltage conversion means to be less than or equal to a sum of a predetermined voltage plus the voltage of said power supply line; wherein said voltage conversion means is a charge-pump circuit and said clamp means includes a constant voltage drop circuit, connected to said charge pump and said gate of said MOS transistor at a first end; a first transistor, connected to a second end of said constant voltage drop circuit and ground, conductance of said first transistor controlled by a connection to the power supply; and a second transistor connected to said second end of said constant voltage drop circuit and ground, conductance of said second transistor controlled by a connection to said MOS transistor.