Design of Hybrid Dual-Path DC-DC Converter with Wide Input Voltage Efficiency Improvement

Type-IV dual-path step-down (T4 DPSD) converter is proposed with conversion efficiency improvement over wide input voltage. The proposed T4 DPSD converter adopts inductor and flying capacitor as power conversion elements, reducing power loss caused by large DCR in conventional Buck converter. Furthermore, the voltage stress of power devices and inductor current ripple are relieved. Thus switching loss and conductance loss are optimized simultaneously. Compared to previously proposed DPSD converters, the proposed T4 DPSD converter features negative voltage switching node. High-swing bootstrap (HSB) gate driver circuit with enhanced PSRR (Power Supply Rejection Ratio) is designed to charge bootstrap capacitor to adequate voltage, even if at lowest input voltage. Consequently, the full load efficiency at 5A is improved from 85% to 89.3%. And the peak conversion efficiency is 95.6% when input voltage is 2.7V to 4.2V with output voltage of 1.2V.