A Linear Lithium Battery Charger

The application of lithium-ion battery, greatly facilitate the people’s daily lifeand scientific research in order to adapt to the needs of the people and marketlithium-ion battery with the times changing their look, and continuously improve theability of the service of humanity.Lithium relative to other types of batteries (such asnickel cadmium, nickel metal hydride) has a light weight, small size and energydensity features, more in-depth study of lithium-ion batteries also have a greatsignificance.This article from the lithium battery chemistry characteristics and work principle,through to the rechargeable battery characteristics and principle of knowledge,completed a lithium ion battery charger IC Design of linear. The lithium-ion batterycharger via the PROG pin to set the size of the charging current, the maximumcurrent can reach more than800mA, and can also change the external circuit to theUSB port of the computer and other charge. Chip internal use of three stage chargingmode for battery charging, namely: the battery from discharge state when theprecharge phase, the constant current charging stage and the constant voltagecharging stage. The main advantage of this charging method is able to obtain a shortercharging time and high charging efficiency.The charger IC discussed in this thesis,is designed to charge single celllithium-ion batteries. Thanks to the built-in power tube and the substrate voltageselect circuit, without the need for external MOSFET, the detection resistor and theisolating diode.To decease the power loss and money cost,the IC was design usingstandard CMOS technigue while the power transistor was integrated into the chip,andfew external components are needed in application. The chip can also monitor thecharging current, with automatic charging cycle characteristics, and has a twoindicator pin indicating end of charge state and input voltage state.The structure andprinciple of each module also are presented, and one by one to achieve the simulation.The circuit is simulated via Cadence Spectre based on0.6um CMOS process,whose results demonstrate the excellent performance of the Li battery chargerIC described in this thesis.