As portable devices have been widely spread in nowadays, PMIC with a high efficiency in wide load range have been the main design focus. In this paper, an accurate bang-bang zero-current detector to prevent reverse inductor current and a triple mode switched inductor-capacitor buck converter to extend load range are presented. The proposed converter sustains minimum power conversion efficiency of 85% in the output load range from 100uA to 300mA. The chip was fabricated in a 0.18um CMOS process.