Research Of Synchronous Rectification BUCK DC-DC Controller With Novel Lossless Current Sensing

Power supply and Power Management Integrated Circuits are essential part of every portable device, providing regulated voltages to various subsystems. With the rapid development of So C, more devices are being packaged on a single chip, thus requiring the power supply to provide high current and low output voltage capability. The widely used conventional res current sensing results the power efficiency degradation of the DC-DC converter especially in high load current application.A current-mode synchronous rectification BUCK DC-DC controller with novel lossless current sensing is presented in this dissertation. The proposed controller is capable of sensing the inductor peak current with DCR sensing, it can provide higher efficiency for applications of high output currents. The maximum current sense threshold of the proposed sensing is programmable for 30 m V, or 50 m V or 75 m V, which making the choice of sensing schemes is a design trade-off between accuracy, cost, and power consumption. The proposed lossless DCR sensing reduces the node of loop system and its circuit structure is simple, which can accelerate the system transient response, and the proposed circuits would improve several points of efficiency compared to the resistor sensing. The temperature compensation circuit will provide correction of the maximum load capability over temperature. The proposed controller enhances the precision of the load voltage regulation in low voltage, high current applications by defferential remote sensing scheme.The dissertation firstly introduces the development background and significance of Power Management Integrated Circuits, and then introduces the latest research status and development trend of PMICs. Secondly, the dissertation comprehensively and thoroughly analyzes the theoretical knowledge of BUCK DC-DC converter, and the conduction loss in low voltage, high current applications. Then, the dissertation presents the proposed system architecture, and mainly focuses on the existing approaches for current sensing and the proposed lossless current sensing. Next, the dissertation presents the design and analysis of the basis and pivotal modules of the controller, and gives the simulation results of its electrical characteristics. Finally, the dissertation introduces the topology of the proposed controller system, and gives the systematic simulation and systematic functional verification.The results of systematic simulation shows that the proposed controlled work properly, the pivotal function and parameters meet the design requirements. The functions of DCR sensing and differential remote sensing work properly. The system has good line and load transient response and high efficiency, and improves several points of efficiency compared to the resistor sensing.