Buck regulator controls white LED with optical feedback

摘要

There is much interest in LED-based lighting due to the availability of high-power, high-efficiency white—and other-color—LEDs (Reference 1). Because an LED is a current-controlled device, typical control circuits regulate the current through the LED to maintain uniform intensity. To optimize available power, users often operate the LEDs with a switching-converter circuit—either a buck or a boost converter—depending on the input-dc voltage.