Patent ID: 6690559
Filing Date: 2004-02-10
Classification: H02J

Abstract:
A charge/discharge type power supply, comprising:a chargeable and dischargeable secondary battery having a positive and negative terminals; a switching element being connected in series to said secondary battery; an external connection positive terminal and an external connection negative terminal which are connected to a charger or a load, said external connection positive terminal being connected to said positive terminal of said secondary battery, and said external connection negative terminal being connected to said negative terminal of said secondary battery through said switching element; and a charge/discharge control circuit being connected in parallel with said secondary battery and having an over-current detection terminal being connected to said external connection negative terminal, wherein said charge/discharge control circuit monitors a voltage across said secondary battery, a voltage across said switching element and a voltage between said external connection positive terminal and said external connection negative terminal to control the on/off operation of said switching element; wherein said switching element is a MOS transistor having a source, a drain, a gate and a body that are separated from each other, and diodes are inserted between the body and the source of said MOS transistor and between the body and the drain thereof so as to be oppositely directed.