Design Support

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White LEDs are quickly becoming the light of choice for backlighting of small color displays because of their falling costs, longer life, and smaller size. The problem this presents is that the white LED has a high voltage drop (3.1 V to 4.0 V depending on manufacturer) as compared to the monochrome displays' green LED with a voltage drop of 1.8 V to 2.7 V. Whereas the green LED can be powered directly from the commonly used Li-Ion battery, with a linear regulator, and a ballast resistor, the white LED used for backlight or frontlight purposes will requires the battery voltage be boosted.