選擇脫機(jī)LED驅(qū)動(dòng)拓?fù)涞奶魬?zhàn)

　　LED陣列的驅(qū)動(dòng)要求與總體設(shè)計(jì)標(biāo)準(zhǔn)相差很大。您選擇的驅(qū)動(dòng)拓?fù)湟彩侨绱恕?/p>

　　當(dāng)考慮將交流輸入電壓恒定調(diào)節(jié)電流源的LED負(fù)載LED驅(qū)動(dòng)器的拓?fù)浣Y(jié)構(gòu)，有助于觀(guān)三總功率級(jí)LED應(yīng)用：低功耗應(yīng)用需要小于20瓦的輸入，例如，光條，r-lamps，和白熾燈；中功率下的光和l-light應(yīng)用50瓦的輸入；大功率標(biāo)志或路燈照明要求高于50瓦的輸入。設(shè)計(jì)者在這三種功率范圍內(nèi)面臨不同的挑戰(zhàn)，從成本、空間到LED驅(qū)動(dòng)程序、效率、設(shè)計(jì)復(fù)雜度、功率因數(shù)、平均故障時(shí)間和可靠性，但其中只有一些挑戰(zhàn)。建議在這三個(gè)基本功率范圍內(nèi)的基本拓?fù)湟詽M(mǎn)足設(shè)計(jì)挑戰(zhàn)。

　　The low-power solutions targeting small lamp sizes require small design volumes to fit the LED driver， consistent light radiation by controlling the current through the LED， efficiency， and low cost. In order to be compliant with Energy Star Program Requirements for Luminaires， the light fixture must have a power factor ≥0.7 for residential applications and ≥0.9 for commercial applications for input power greater than five watts.1 If isolation from the LED driver is not required， a buck regulator topology is the lowest BOM and therefore a low cost solution to consider. Figure 1 is a non-isolated buck topology example which also includes power factor correction and dimming capability. There is only one magnetic component， which is a simple inductor and a single MOSFET/diode pair for buck power conversion. This topology choice is best selected when the input voltage is larger than the output voltage required from the LED load.