Used In Portable Products, High Efficiency Synchronous Rectifier Boost Converter Design

In today's electronic market, protable applications as the major parts of comsumer electronics are gaining more and more chances to develop, making the power management products of comsumer electronics superior to those of communications, becoming the major parts of the whole power management products. The research of power management of protable applications is becoming a hot-pot. In this background, first, the future development of the portable applications was analysised; and then, the key points of the power management IC of the portable applications were summarized: high efficiency, low power losses, small size, wide input voltage range and low cost, etc;then the design principles of the power management IC of the portable applications were summarized; finally,a hign efficiency synchronous Boost converter applied to protable applications was designed,Which could achieve over 90% efficiency during input volage range from 2V to 5V. The highest efficiency is more than 96%. Combining the merits of the voltage feedback and voltage feedforward, the system achieved excellent line-regulation (0.08%) and load-regulation (0.71%).This power management IC could be used in all kinds of portable applications such as: MP3/MP4 player, smart Cell Phone, Personal Digital Assistant (PDA), and Portable Media Player (PMP) etc.During the circuit design, the design objects were first proposed based on the key points of the portable applications power management IC; then the system stage design principles and circuit stage design principles met the requirement of the portable applications power management IC were summarized; at last, the power stage, control loop and stability of the feedback loop were designed and analysised respectively. During the design process, the theory of efficiency, line-regulation, load-reguation improvement were achieved by the small single models of synchronous power stage and voltage feedforward control mode.The sub-circuit, including bandgap voltage reference, trans-conductance ampilifier, synchronous control and zero-crossing and anti-ringing block, referenced in the system stage design,were designed in detail and simulated with process corners. The function of the whole circuit were simulated and verified by all the sub-circuits combined together, and met the orginal design object well.