可集成于AC-DC转换器的带修调高性能振荡器

提出了一种适用于反激式AC-DC芯片的高效、可修调振荡器电路。相对于传统的振荡器,增加了一块模式控制电路,通过检测负载反馈端电压,可灵活选择两种不同的工作模式,产生不同频率,从而实现芯片在所有负载下都可以保持较高的工作效率。修调电路可以对主电容充放电电流进行调节,实现频率抖动,从而减小EMI的影响。利用华润上华0.8μm 40V高压BCD工艺,对提出的电路进行仿真验证。结果表明,所有负载下变换器转换效率均可达到85%,负载变化时,频率可变范围为22～66kHz,修调电路实现4%的频率抖动。

A High-Performance Oscillator with Trimming for AC-DC Converter

A high-performance oscillator with trimming for flyback AC-DC converters was proposed,in which a mode control circuit was used,compared to conventional oscillators.By checking voltage at load feedback port,two operation modes could be chosen to generate different frequencies,which made the AC-DC converter IC work efficiently at all loads.The trimming circuit could achieve frequency jitter to reduce effects of EMI by regulating charge and discharge current.The circuit was designed and simulated based on 0.8 μm 40 V BCD process.Simulation results indicated that the converter achieved an efficiency up to 85% at all loads,and a variable frequency range from 22 kHz to 66 kHz for different loads,and the trimming circuit achieved a frequency jitter up to 4%.