用于LED驱动器的扩频振荡器的设计与实现

Design and Implementation of Frequency Extension Oscillator for LED Driver

摘要:

为了解决传统LED驱动器引入的电磁干扰(EMI)问题,提出了一种具有扩频功能的片内振荡器。该电路采用频率扩展技术对时钟进行频率调制,可有效抑制电磁干扰,并具有固定频率模式(FFM)和扩频模式(FEM)两种工作模式,且固定频率时温度漂移小。采用0.18μm BCD进行了工艺仿真,结果表明:扩频模式下,振荡器的中心频率为558kHz,扩频范围为6.09%,频率抖动周期为57.8μs,EMI能量降幅高达12dB,显著降低了电磁干扰,适用于对电磁兼容(EMC)性能要求很高的特定LED驱动器中。?更多还原

Abstract:

An oscillator with the function of frequency extension was proposed to suppress the electromagnetic interference(EMI) problem in LED driver. With the clock frequency modulated by frequency extension technology, EMI can be restrained effectively, and two working modes of frequency-extension mode(FEM)and fixed frequency mode(FFM)can be choosen, which drifts little across temperature. Process simulations based on 0.18μm BCD show that the clock was extended 6.09% up and down the central frequency of 558kHz in a period of 57.8μs, and EMI power reduces by 12dB. Due to its inhibition of EMI, the circuit was suitable for LED driver power supply that requires higher electromagnetic compatibility.