中文摘要：

设计了一种不连续导通模式（DCM）下高效反激式转换器的控制方案。该方案通过电压检测（VS）端电感检测功率MOS管的导通状态,通过控制电路对VS信号进行采样和保持,采样值输入至降频电路产生降频电流,降低振荡器的工作频率,从而减少功率MOS管的开关损耗,提高转换器的工作效率。在不同的输出负载下,VS的采样值产生不同大小的降频电流不同程度降低振荡器的工作频率,实现对系统的脉冲频率调制和脉冲宽度调制的结合控制。本电路采用0.5μm BiCMOS工艺,利用Hspice和Cadence软件对设计的电路进行仿真。仿真结果表明,转换器的效率高达86%,在0.1 A轻载情况下效率也达到了72.1%,较高的工作效率满足设计要求。

英文摘要：

A control scheme for the high efficient fly-back converter under the discontinuous conduction mode（ DCM） was designed. The scheme uses the voltage sense（ VS） pin to detect the conduction state of the power MOS transistor,by control the circuit to sample and hold the VS signal,the frequency reduction circuit generates a current under logic control with the sample values input,which can reduce the operating frequency of the oscillator and the switching losses of the power MOS transistor to improve the efficiency of the converter. Under different output loads,different currents generated by the VS sampling voltages reduce the operating frequency of the oscillator at different levels,and finally a combination control of the pulse frequency modulation and pulse width modulation is achieved. Based on0. 5 μm BiCMOS process,the circuit of the converter was simulated using Hspice and Cadence software.The simulation results show that the efficiency of the converter is up to 86%,and at a light load of100 mA the efficiency reaches 72. 1%,thus the high operating efficiency meets the design requirements.