Fast Charging and High Ef ficiency Switching-Based Charger With Continuous Built-In Resistance Detection and Automatic Energy Deliver Control for Portable Electronics Tzu-Chi Huang, Ruei-Hong Peng, Tsu-Wei Tsai , Student Member , IEEE,K e - H o r n g C h e n, Senior Member , IEEE

Abstract

The continuous built-in res istance detection (CBIRD) is proposed in the switching-bas ed charger system to achieve fast charging. Corresponding to buil t-in resistance (BIR) variation of Li-ion battery and charging current limitation from input energy, the CBIRD dynamically adjusts the transition voltage at the constant current (CC) mode. As a result, the transition timing from CC mode to the constant voltage (CV) mode can be postponed. Rated large charging current and extended period in CC mode effectively reduce charging time. Besides, the proposed automatic energy deliver control (AEDC) technique considers both loading system and battery status simultaneously to manage charging current according to the loading system’s requirement and input supply energy for high ef ficiency charging. The pro- posed switching-based charger system was fabricated in 0.25 µm CMOS process and occupied 3 mm 2 silicon area. The charger system can save up to 40% of charging time. The charger system achieves 87% of peak power ef ficiency at a rated 1 A charging current.