AN026

AN026 The Charger Design with SEPIC Converter Introduction Recently, the hand-held devices become more and more popular, such as Personal Digital Assistant (PDA), CD workman, digital camera etc… need a great quantity battery for normal operation. Considering the economic effect, the battery chargers for recycle rechargeable battery, like NiMH or NiCd, are extremely important. In this article will introduce the design idea of charger circuit at first. Then directed against the characteristics of rechargeable battery and use AIC1781 to design a charge protector only for NiMH/NiCd battery. Design Idea of Battery Charger I’ll give an example to illustrate the relationship between rechargeable battery and battery charger. Assume that the battery is a cup, and regards the constant current, which from charger, as the water pour into the cup. The more water pour into the cup, the more volumes will be in the cup. Contrast with the battery and charger, the more current flow into the battery...