A Universal Protection Controller for Li-ion Battery Charger

A universal protection controller for Li-ion battery charger is proposed in this paper. First, an in-depth analysis on Li-ion battery charger protection has been made, then a detailed system description was given, and finally test results were presented. This IC provides battery thermal protection, due time termination, bad cell detection, automatic recharge and state indication, which are usually neglected in conventional charger design. Furthermore, a new approach has been introduced to implement the battery thermal control unit for the system. With the battery thermal protection module, the charge current could be set according to a typical, not the worst-case, ambient temperature, which helps to accelerate the charging process. A novel oscillator without comparator is designed to generate the system clock. The protection controller IC was fabricated in 1.5 ¿m BCD (Bipolar CMOS DMOS) technology. The proposed functions of the IC were verified by simulation and measurement.