Voltage Multiplier LED Driver Circuit

Published:2013/9/15 21:42:00 Author:lynne | Keyword: Voltage Multiplier LED Driver Circuit | From:SeekIC

A voltage multiplier is applied as a high source impedance, 36V, 300mA, 12W LED driver. The high source impedance is ideal for driving power LEDs because it accommodates variations in LED junction voltage so that there is minimal change in LED current and brightness. The cascade multiplier is essentially a charge pump that is similar to the popular off-line capacitor limited LED drivers, but offers a substantially higher load current capacity as well as transformer isolation. Note that this circuit topology and application is new to the world. LEDs are essentially constant voltage devices. Unfortunately, LEDs vary in voltage due to manufacturing variations and temperature. Thus the “constant voltage” is not constant at all—this leads to variations in current when devices are paralleled and also presents a problem when operated from constant voltage power sources—and a serious problem when powered via automotive systems that range from 11 to 14.5V.



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