本文提出了一款高效率、宽输入电压的边界导通模式反激变换器结构。为了防止负载切换过程中芯片过压和欠压,提出了一种由电流调节电路(CRC)与自适应频率控制电路(AFCC)组成的新型模式切换环路,实现了芯片在不同模式之间的平滑切换,提高了负载的瞬态响应和转换效率;通过在环路中引入电流调节控制技术,减小了低纹波突发模式(LRBM)下的原边充电电流和输出最小负载电流,从而减小轻负载下的开关频率,降低功耗。基于0.18 μm BCD工艺,实现了电路设计和版图设计,芯片面积为1.48×2.5 mm²。仿真结果表明,变换器在输入电压为3~32 V、输出电压为5 V时,轻、重负载切换过程中的输出电压瞬态响应最大变化为6%,峰值转换效率为88.6%。

This paper presents a high-efficiency wide input voltage boundary conduction mode flyback converter.To prevent chip overshoot and undervoltage during load switching,a new mode switching loop composed of current regulating circuit (CRC) and adaptive frequency control circuit (AFCC) is proposed.This configuration facilitates smooth transition between different modes,enhancing the transient response of load and the conversion efficiency of chip.Additionally,the current regulation control technology is introduced into the loop to reduce the charge current on the primary side in low ripple burst mode which lowers the minimum load current on the secondary side,thereby reducing switching frequency under light loads and power consumption.Based on the 0.18 μm BCD process,the circuit design and layout design are realized,and the chip area is 1.48×2.5 mm².The simulation results show that under input voltage ranging from 3~32 V and output voltageat 5 V, the maximum change of the transient response of the output voltage is 6% and the peak conversion efficiency reaches 88.6%.