光电耦合器是DC/DC电源的关键器件,光电耦合器低频噪声的随机增大是该类电源主要失效模式之一。目前,国内尚未形成光电耦合器低频噪声的有效测试方法,更未建立相关标准。文章详细分析了光电耦合器低频噪声特性及产生机理,提出了其低频噪声测试的偏置电路、测试设备和测试方法。针对用于DC/DC电源的典型光电耦合器(4N47)的实测结果表明,该方法能够准确测试光电耦合器的低频噪声,为DC/DC电源用光电耦合器的系统适用性和典型故障提供了一种有效的评估方法。 Optocouplers are the key components of DC / DC power supply. The random increase of low frequency noise of optocouplers is one of the main failure modes of this type of power supply. At present, the domestic has not yet formed an effective test method of low-frequency noise optocoupler, but did not establish the relevant standards. In this paper, the low frequency noise characteristic and mechanism of optocoupler are analyzed in detail. The bias circuit, test equipment and test method of low frequency noise test are proposed. The experimental results of a typical optocoupler (4N47) for DC / DC power supply show that this method can accurately test the low frequency noise of optocouplers and provide the system applicability and typical fault of optocoupler for DC / DC power supply An effective assessment method.