An Automotive 12 V-to-1.2 V Integrated Switched-Capacitor DC-DC Converter for Improved Load Transient Response

This letter presents a 12 V-to-1.2 V switched-capacitor dc-dc converter, which has a voltage conversion ratio of 1/10 with an input voltage of 12 V, for automotive applications. The power stage comprises an 8-phase ladder converter and a 16-phase 3-to-1 converter. All power switches are designed using 5-V isolated CMOS transistors. To improve the load transient response, the bias current for the charge pump of the 3-to-1 converter is adjusted via a dynamic amplifier. The charge pump for the ladder converter is assisted by the feedback loop of the 3-to-1 converter so that it responds fast to the light-to-heavy load transition. The proposed phase-shedding control reduces the overshoot when the load current increases. The proposed work is fabricated in a 180-nm BCD process. For a load step of 60 mA, the light-to-heavy and heavy-to-light responses are improved by 47.28% and 52.50%, respectively. The maximum end-to-end efficiency is measured as 57.80%.