摘要
针对伪固定频率自适应导通时间控制器频率特性差与输出纹波大的问题,提出了一种新颖的内部补偿改进方案。一方面通过在内部导通时钟电路中加入校正补偿方案,提高了系统开关频率的稳定性;另一方面在每次高端功率管导通时,在基准上开始叠加与开关周期呈正比的斜坡补偿信号,并在同步续流管关断时,使叠加信号复位,降低了输出反馈端对纹波的要求。该设计方案已在一款基于0.5μm BCD工艺的单片DC-DC控制器芯片中得到验证,测试结果显示,系统工作频率稳定在400kHz,随输入输出电压变化小于5%。负载电流从0～6A的突变中,输出电压的上升与下降沿的跳变小于70mV,且稳定后的纹波小于20mV。
A novel and improved compensation of the internal circuit is proposed to reduce the output voltage ripple and the frequency shift of an adaptive on-time and pseudo fixed frequency controller.One method is the calibration of the internal adaptive on-time controller to enhance the stability of the switch frequency.And another,when the upper power device is on,the slope signals proportional to the switch cycle are added to the reference voltage,and then reset the slope signals on the moment the rectifier device is off to reduce the required ripple at the feedback point.With the above two technology of compensation,the characteristics of the ripple and the frequency are improved.The proposed circuit is fabricated in a single DC-DC controller based on 0.5um BCD process.The test results show that the fixed system switch frequency is 400kHz within 5% changed.Also,the rising and falling overshoot are less than 70mV with the output current from 0 to 6A,and the ripple is less than 20mV in the normal operation.
出处
《电工技术学报》
EI
CSCD
北大核心
2011年第9期190-195,共6页
Transactions of China Electrotechnical Society
基金
国防预研基金资助项目(51308010610)
