驱动高电压、高亮度LED

　　驱动高电压、高亮度LED

　　hvhb发光二极管，当驱动在PFC升压配置，具有小尺寸、高功率因数、效率高、成本低的优点，且复杂度低，CFL照明解决方案提供具有竞争力的替代。

　　作为消费者，公司，甚至国家寻找低成本、高效节能的照明光源，发光二极管（LED），和紧凑型荧光灯（CFL）已成为主要的替代品。这两种解决方案都是可行的，但差别很大。CFL照明设备价格低廉，但开启速度较慢，表现出较差的调光性能。另一方面，LED具有“抓拍”的特性和暗淡的效果，但由于成本的采用而变得缓慢。

　　半导体制造商继续创造新的LED驱动组件，以降低系统复杂性和成本。与此同时，LED生产商们正在大力提高高亮度LED的效率（发光效率），以减少所需的LED数量，并减少调节它们所需的功率。

　　One such innovation is the introduction of high-voltage， high-brightness （HVHB） LEDs. These LEDs require a much higher voltage to start current flow and， therefore， light emission. These new LEDs present new challenges and opportunities. While originally designed to be self-driven directly off of an AC line， factors such as low efficiency， low power factor， and the inability to dim limit the number of applications they can serve.

　　In Figure 1 we see the problems in driving these LEDs directly off of the AC line. In an effort to meet the entire voltage range （90 to 135 Vac or 207 to 253 Vac）， the forward voltage drop （Vf） must be at the lowest AC voltage or lower. This means that when the voltage is at the upper limit of the scale， the voltage falls across the current-limiting resistor. This creates a loss and greatly reduces efficiency. This also creates heat， which may limit the life of the LED.