Patent ID: 7719283

Claim:
A switching circuit, comprising: a capacitor; a combination battery, having a plurality of unit cells connected in series, each of the unit cells containing battery; a plurality of change-over switches, sequentially connecting both ends of the each of the unit cells to the capacitor, wherein each of the change-over switches has two semiconductor switches connected in series so that the source-drain directions thereof are oriented opposite to each other; a first logic circuit, outputting a control signal for designating an on-off of at least one of semiconductor switches; and a level shift circuit including a semiconductor switch, and when the semiconductor switch is open, level shifting a voltage of the control signal so that the level shifted control signal has a voltage higher than the control signal and feeding the level-shifted control signal to a gate of the at least one of the semiconductor switches; wherein a voltage is applied to the at least one of the semiconductor switches by a first cell of the plurality of unit cells, and a voltage of the level shifted control signal is applied to the gate of the at least one of the semiconductor switches by the first cell and a second cell of the plurality of unit cells, which is connected in series to the first cell.