A novel universal battery charger for NiCd, NiMH, Li-Ion and Li-Polymer

A universal monolithic battery charger is presented, capable of automatically detecting the number and type of battery cells, NiCd, NiMH, Li-Ion and Li-Polymer. Different charging modes are supported from constant-current voltage-limited to constant-voltage current-limited with a wide range of charging rates, current or voltage limitations. A novel control using continuous and switched loops regulates the current and voltage concurrently during the various phases of the charging process. In addition, various end-of-charge detections are available, namely the detection of residual charging current for Lithium batteries, peak voltage for Nickel batteries, and safety detections including under and over voltage and temperature, and time-out detection. The charger IC is implemented in a 5V, 0.5mum triple-metal standard CMOS process, requiring 8 pins and a total silicon area of 3mm(2). Three external resistors and a charging transistor complete the charger.