一种具有750mA输出电流,双模式PWM/PFM控制的高效率直流-直流降压转换器  

A 750mA,Dual-Mode PWM/PFM Step-Down DC-DC Converter with High Efficiency

作　　者：陈东坡[1] 何乐年[1] 严晓浪[1] 

机构地区：[1]浙江大学超大规模集成电路研究所,杭州310027

出　　处：《Journal of Semiconductors》2008年第8期1614-1619,共6页半导体学报（英文版）

基　　金：浙江省重点科技计划资助项目(批准号:2007C21021)~~

摘　　要：提出了一种输出电流可达750mA,脉宽调制（PWM）和变频调制（PFM）双模式控制的,高效率、高稳定性直流-直流降压转换器.该转换器在负载电流大于80mA时,采用开关频率为1MHz的PWM工作模式;在负载电流小于80mA时,采用开关频率减小和静态电流降低的PFM工作模式,实现了在整个负载电流变化范围（0.02~750mA）内,转换器均保持高效率.而且采用一种快速响应的电压模式控制结构,达到了优异的线性和负载调整特性.芯片采用CSMC公司0.5μm CMOS 2P3M混合信号工艺物理实现.测试结果表明,该电路可根据负载的变化在PWM和PFM模式下自动切换.最大转换效率达96.5%;当负载电流为0.02mA时,转换效率大于55%.该芯片特别适合电池供电的移动系统使用.A 750mA output current, high stability, high efficiency step-down DC-DC converter with pulse-width modulation and pulse-frequency modulation modes is presented. Under nominal load current （〉80mA）,the converter operates in PWM mode with a fixed switching frequency of 1MHz. At light load current （〈80mA）,the converter enters PFM mode operation with reduced switching frequency and less quiescent current. Therefore, the converter achieves the highest efficiency over the entire load current range from 0.02 to 750mA. Moreover,an advanced fast response voltage mode control scheme achieves superior line and load regulation. The chip was implemented using a CSMC 0.5μm CMOS 2P3M mix-signal process. Simulation results indicate that the converter can automatically switch between PWM-mode and PFM-mode according to the load current. The maximum conversion efficiency is up to 96.5% and it is more than 55% at 0.02mA of load current. The proposed chip is especially suitable for portable systems powered by batteries.

关 键 词：DC-DC转换器 降压转换器 脉宽调制 变频调制 高效率 

分 类 号：TM46[电气工程—电器]