一种多模式AC/DC控制芯片的设计

根据QR、PWM、PFM模式及绿色模式在特定负载下才具有高效率的特点,提出了一种多模式工作的准谐振反激式AC/DC控制芯片设计方案.通过分别控制导通时间与开关周期,并根据负载的轻重情况,芯片自动切换成4种工作模式.通过芯片内部的多模式功能,克服了准谐振模式在轻载及待机状态下效率较低的问题.整个芯片基于1.5μm BCD(Bipolar-CMOS-DMOS)工艺设计.SpecterS的仿真结果表明:在全负载下实现模式的自动切换,具有较高的转换效率,适合使用于负载变化范围较大的AC/DC变换器.

Design of Multi-Mode Quasi-Resonant AC/DC Controller

QR(Quasi-Resonant) mode,PWM(Pulse Width Modulation) mode,PFM(Pulse Frequency Modulation) mode,and green mode have high converting efficiency only in the specific load condition.Taking advantage of this feature,the paper proposes a multi-mode quasi-resonant flyback AC/DC controller.By controlling the conduction time and switching frequency separately,chip can switch mode to fit the particular load condition.The low efficiency problem in light load or standby condition of QR mode is overcome by this multi-mode function.The whole chip is designed and simulated by spectreS in 1.5um BCD(Bipolar-CMOS-DMOS) process.The simulation result shows that automatic mode switching is achieved,and AC/DC converter's efficiency is comparatively high.This controller suits AC/DC converter which could be used in wide range load condition.