A Light-Load-Efficient 11/1 Switched-Capacitor DC-DC Converter With 94.7% Efficiency While Delivering 100 mW at 3.3 V

Abstract

This paper demonstrates a 2-phase 11/1 switched-capacitor (SC) DC-DC converter that provides an output voltage $V_{OUT}$ of 3.3 V from an input voltage $V_{IN}$ in the range of 37.4 V–39 V . SC converters, unlike their inductive buck counterparts, do not rely on the pulse-width modulation (PWM) duty cycle to set the voltage conversion ratio (VCR) as this is determined by the SC converter topology. Consequently, SC DC-DC converters do not require a very low duty cycle, resulting in a short $t_{on}$ for the full-input-voltage-rated high-side switch and significant driver power consumption. Instead, a two-phase SC converter is found to be an excellent candidate for high-ratio voltage conversion as it maintains a 50% duty cycle and exchanges few components of high voltage rating with more that are rated for lower voltage.