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降压调节器使驱动高亮度LED容易
“垃圾输入，垃圾输出”不只是适用于计算机编程。LED产生的光的质量直接关系到驱动器的电压和电流的质量，这使得驱动电路和发射器一样重要。对于低亮度LED，线性调节器通常可以完成这项工作。高亮度应用提出更严格的性能规格，促使工程师选择更先进的解决方案，如开关稳压器，开关电容转换器或反激式转换器。在这个组中，降压开关降压开关通常是首选，因为它们简单、高效且易于稳定。当适当地指定和设计成一个系统时，降压调节器可以提供令人印象深刻的成本/效益性能。
LED是直接带隙半导体，其输出随电压的变化而非线性变化（图1）。阈值电压，或正向电压（VF），从设备到设备的任何类型的LED略有不同。即使是单个设备，VF也会随温度和年龄的变化而漂移。相反，作为驱动电流函数的输出对于任何设备都是线性的，所以用恒流源驱动led提供最佳性能。
Figure 1： LED current varies nonlinearly with respect to voltage. （Courtesy： RECOM）
Drive circuitry is often an afterthought， especially for lighTIng designers. Focusing on the illuminaTIon aspects of the design and leaving the power aspects for the end may compromise performance and manufacturability.
“［Designers］ want to make their fixture look a certain way and generate a certain amount of light，” says Alex Craig， applicaTIon systems engineer for lighTIng， Fairchild Semiconductor. “As a result， they might put six LEDs in parallel， but six LEDs in parallel are likely not as efficient as six LEDs in series.” Smart engineers take a holistic design approach by developing an efficient lighting configuration that lends itself to common power topologies.
