The IC automatically senses the DC input supply and battery insertion or removal. Heavily discharged batteries are initially charged at a C/5 rate before a fast charge is applied. Fast charge is terminated using the V detection method. Backup termination consists of a programmable timer and battery overvoltage detector. An optional external NTC thermistor can be used for temperature-based qualification of charging. An optional programmable recharge feature automatically recharges batteries after discharge. Manual shutdown is accomplished with the SHDN pin, while removing input power automatically puts the LTC4060 into sleep mode. During shutdown or sleep mode, battery drain is <1A.