升压和开关稳压器驱动高亮度LED

　　升压和开关稳压器驱动高亮度LED

　　在这三部分关于发光二极管（LED）驱动程序的第一部分中，我们讨论了降压型升压开关稳压器、开关电容变换器和反激变换器。该系列产品首先从低亮度LED系统的复杂性、效率和成本平衡入手，并继续使用降压调节器驱动高亮度LED。最后一部分是关于驾驶性能。

　　从LED获得最佳性能需要正确的驱动程序。线性稳压器为低功率LED提供了一种简单而经济的解决方案。然而，它们将系统功率的很大一部分消耗在热量上，使它们成为大功率LED的一个不良选择。开关稳压器提供了更有效的解决方案。降压（降压）开关稳压器是一个很好的开始，但只有当LED驱动电压低于电源。当LED需要更高或不同的电压时，升压（升压）或降压开关稳压器提供更好的选择。

　　发光二极管的光输出随电压的变化呈非线性变化。更复杂的是，正向电压（VF）也随着温度和年龄的增加而漂移。幸运的是，LED输出与电流近似线性。恒流驱动程序提供最好的结果，尤其是在当前匹配能力增强的情况下。

　　LEDs can be linked together in series or in parallel， but neither configuration is always better. The best choice varies from case to case， depending on the parameters of the devices and the needs of the application. When wired in series， LEDs in a string continue to operate even if one or more fail by short circuiting. The series configuration also provides current matching， which ensures consistent output. On the downside， series connections require higher voltages， which limit driver options and increases regulatory requirements. Also if an LED fails open， the entire string goes dark.

　　The alternative， parallel configuration operates with lower voltages. However， it does not provide current matching， which is important to consider， given the random device-to-device variation among LEDs that can cause inconsistent light output between LEDs.