Research on Improving the Efficiency of Heavy Load DC-DC Converters through Adaptive On-Resistance

Abstract

To address the issue of low conversion efficiency in DC-DC Boost converters under heavy load, this paper utilizes a technique of adaptive on-resistance control for power MOSFETs. By setting different drive voltages in different load ranges, the on-resistance of power MOSFETs is reduced, addressing the issue of significant conduction loss at heavy loads. In addition, using pulse skipping modulation (PSM) and partially turning off power MOSFETs can improve the system’s conversion efficiency at light loads. Based on 0.18μm BCD technology, specific verification of this method was completed in an actual chip. The results show that with an input voltage of 3.7V, output voltage of 5V, and operating frequency of 1.5MHz within a wide load range from 10mA to 900mA, the system can adaptively adjust the on-resistance of power MOSFETs. This increases efficiency from 83% to 91.7% when the load current equals 900mA and achieves efficiencies above 90% across the entire load range, with a peak efficiency reaching 96.5%.