Charge control circuit

Claim 1

A charge control circuit comprising: an excess charge detecting circuit and a charge changeover circuit of a secondary battery operated by an electromotive force of a power device, said excess charge detecting circuit being connected between a first line connected to both a positive terminal of said power device and a positive terminal of said secondary battery and a second line connected to a negative terminal of said power device, said excess charge detecting circuit comprising a first stage having a source of a first P channel MOSFET connected to the first line, a gate thereof connected to a negative terminal of the secondary battery and a drain thereof connected to both a drain and a gate of a first N channel MOSFET connected to the second line, a second stage having a source of a second N channel MOSFET connected to the second line, a gate thereof connected to the drain of the first N channel MOSFET and a drain thereof connected to the first line by way of a resistor, and a third stage having a source of a second P channel MOSFET connected to the first line, a gate thereof connected to the drain of the second N channel MOSFET, a drain thereof connected to a drain of a third N channel MOSFET, a gate of the third N channel MOSFET connected to the drain of the first N channel MOSFET and a source of the third N channel MOSFET connected to the second line.