平衡低亮度led系统的复杂性、效率和成本

　　平衡低亮度led系统的复杂性、效率和成本

　　固态照明占据了头条新闻。然而，低功耗LED仍然是该部门的工作母机，功能从简单的指示灯用于便携式设备的背光显示。虽然这种LED设备已经很好地建立，开发适销对路的产品需要彻底了解技术和所涉及的权衡。

　　该系统的一个重要组成部分是驱动电路。权衡影响决定使用一个简单的电阻电源，线性稳压器，或额外的复杂的开关稳压器（见图1）。

　　Figure 1： Used with an adjustable power supply， the BCR 320 family of linear regulators can drive 0.5-W LEDs with a power dissipation of just 1 W. （Image courtesy of Infineon）。

　　The optimal driver circuitry choice depends on the requirements—and balancing the design complexity， efficiency， and cost.

　　Basic current， light， and cooling needs

　　By definition， LEDs are light emitting diodes. That is， the current into the LED must be regulated to avoid failure. One popular technique to regulate current is to design a resistor into the driver. The LED driver also controls both LED output quality and luminous flux—and extends the life of the system.

　　Temperature management is also vital to consistent color and lighting because output wavelength varies with temperature. Also， as with most electronics， elevated temperature reduces life expectancy. Incandescent bulbs radiate heat off of the glass bulb， but LEDs generate most of their heat off the back side of the chip， limiting cooling options to less efficient conductive cooling. As a result， designing drivers for low heat dissipation is important not just for high-efficiency applications， but also for those requiring extreme reliability.