轻载高效Buck转换器设计及其纹波控制方案  

Design of Light Load High Efficiency Buck Converter and Ripple Control Method

作　　者：杨林才[1] 冯全源[1] 

机构地区：[1]西南交通大学微电子研究所,成都610031

出　　处：《微电子学》2014年第4期430-433,437,共5页Microelectronics

基　　金：国家自然科学基金重大项目(60990320;60990323);国家自然科学基金面上项目(61271090);国家高技术研究发展计划(863计划)重大项目(2012AA012305);四川省科技支撑计划项目(2012GZ0101)

摘　　要：提出了一种峰值电流模式PWM下的轻载高效Buck DC-DC控制方案。该方案根据负载大小来自适应调节开关频率和电感电流峰值,实现宽负载范围内高的转换效率和对输出纹波的控制。把误差信号与负载自适应的门限相比较,以判定转换器工作模式。在轻载模式下,通过循环开启或者关闭振荡器来降低转换器的开关频率,降低开关损耗。详细推导了在保持输出电压纹波不变的情况下,负载自适应门限与负载大小之间的关系,并在典型应用下得到二者呈线性关系的结论。采用0.5μm BCD工艺进行仿真,结果显示,在输入电压12 V,输出电压3.3 V下，轻载时最高有94．2％的转换效率，在负载从10mA到500mA变化时，轻载模式纹波为120～140mV，与理论分析的控制纹波130mV较为符合。A buck DC-DC control method based on peak current PWM mode was proposed with improved light load efficiency. This method adjusted switching frequency and peak inductor current adaptively according to load current conditions, keeping high efficiency within wide load current range and controlling output ripple. Through error signal compared with load adaptive threshold, the converter could select different operations. Under the light load operation, the oscillator was turned on or off circularly to reduce switching frequency and switching loss. Relation between load adaptive threshold and load current was derived detailedly under keeping output tipple fixed. Consequently, they were linear relation in typical application. Based on 0.5 pm BCD process, the simulation results showed that under the condition of 12 V input and 3.3 V output, the maximum light-load efficiency could be up to 94.2%. From l0 mA to 500 mA load range, light-load tipples vary from 120 mV to 140 mV, which approximately fit the 130 mV calculation of ripple control.

关 键 词：DC-DC 轻载高效 负载自适应 纹波控制 电感电流峰值 

分 类 号：TN433[电子电信—微电子学与固体电子学]