Falling LED Cost Yields Virtual Device Efficiency Gains

LED systems have traditionally run below the LED datasheet efficiencies. In addition to power conversion losses, LED efficiency drops as they are driven harder, and also as they run hotter. The former phenomenon, called “droop,” follows a cube law (and is currently ascribed to a phenomenon known as indirect Auger recombination). A cutting-edge LED, when driven at its nameplate power rating, might output only 60 percent of its nameplate efficiency rating, which is often specified at reduced drive level. In a case recently brought to the attention of Greentech Media, a special-application LED lamp that used only passive fin-cooling showed a 30 percent increase in output when customers started pointing fans at the units.