混合电源中线性稳压器噪声的理解

　　混合电源中线性稳压器噪声的理解

　　在许多应用中，工程师团队的开关DC-DC电压转换器（“开关稳压器”）与低辍学线性稳压器（LDO）。这样的混合电源是一个很好的方法，以最大限度地提高电池寿命，同时保持无噪声电压供应适合电池供电的产品与敏感的模拟电路。

　　然而，“无噪音”只是相对而言的，因为即使是最好的LDO产生一些噪声。许多工程师认为在LDO的输出噪声是一个简单的电源抑制比（PSRR）功能。当使用一个开关稳压器系列，PSRR的确是一个很好的衡量LDO处理电压和电流纹波的开关稳压器的输出–但比不应该是唯一的标准时，LDO的选择。

　　The LDO has several sources of internal noise generated from its internal components and， worse still， some of this is frequency dependent. It is this combination of PSRR and internal noise that determines the stability of the LDO’s output.

　　This article explains how combining a switching regulator with an LDO can be a good solution for connected， wireless portable products， then leads on to explain why it is important that an engineer analyze the LDO’s datasheet to ensure that its overall noise from the power supply remains within the end-product specification.