为提高PFM开关电源控制电路的抗电磁干扰能力,分析了PFM模式开关电源控制电路的抗电磁干扰原理,提出了随机载波频率调制技术和相应的电路实现方法;列举了几种电源系统抗电磁干扰设计技术,包括ESD保护结构的抗EMI设计方法、电源上干扰的去除方法和基于电压检测电路的抗干扰设计方法.将以上抗干扰设计技术应用在PFM模式开关电源控制电路SX1618中,采用1 μm 40 V高压工艺设计,通过进行流片和封装,并将之应用在实际的开关电源中,其传导EMI通过了相应标准的测试.%To improve Anti-electromagnetic interference level,the principle of anti-EMI for PFM SMPS IC is analyzed, and the Random Carrier Frequency Modulation(RCFM) technology is given,the implementation of RCFM circuit is proposed.Several anti-EMI technologies for power supply are listed,which include anti-EMI design for ESD structure, the method for EMI removing from power supply and anti-EMI design by using voltage detection. RCFM and other anti-EMI technologies are applied to PFM controller SX1618,which is implemented in 1 μm 40 V high voltage process,and the test result shows that the anti-EMI performance is good.
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