Current-Mode Synthetic Control Technique for High-Efficiency DC-DC Boost Converters Over a Wide Load Range

Abstract

This paper proposes a current-mode synthetic control (CSC) technique for the design of boost converters to overcome the difficulty in designing a current-ripple hysteresis boost converter and to maintain high conversion efficiency over a wide load range. The CSC technique has a high accuracy because of the additional voltage path through the error amplifier. A smooth load transient response is maintained when the operation transits from continuous conduction mode with a nearly constant switching frequency to discontinuous conduction mode with a load-dependent switching frequency. Generally, ripple performance, light-load efficiency, and switching frequency are traded off in the design of hysteresis control regulator. In this paper, a balance among the load-dependent switching frequencies at light loads results in high power conversion efficiency compared with conventional pulsewidth modulation converter and attains compact ripple performance. The experimental results show that the output voltage ripple can be kept <50 mV over a wide load current range from 10 to 400 mA, where as power conversion efficiency is maintained at 78% at a load current of 10 mA when the switching frequency is decreased from 5 to 2 MHz.