A high energy efficiency PSM/PWM dual-mode for DC-DC converter in portable applications

Based on the Energy Conservation Rule, an Unideal Energy Balance (UEB) model of a DC-DC converter in Discontinuous Conduction Mode (DCM) is built and the energy efficiency of the power converter is studied. A high energy efficiency PSM/PWM dual-mode for DC-DC converter is proposed in this paper after compared the energy efficiencies of the converter in Pulse Skip Modulation (PSM) mode and Pulse Width Modulation (PWM) mode separately. According to the real time value of energy efficiency, PSM mode is adopted for light loads, while, PWM mode is used for moderate or heavy loads in the proposed PSM/PWM dual-mode, that make the converter keep high energy efficiency in the whole variable loads range. The real time value of energy efficiency is easy to be calculated by the DSP/CPU in the System on Chip (SoC) of a portable appliance and transferred through the data interface I²C.