AF5121

AF5121 Fixed Frequency White LED Step-Up Converter Features  Inherently Matched LED Current  High Efficiency:82%  Drives Up to Six LEDs from 2.2V Supply  20V Over Voltage Protection  Fast 1.4MHz Switching Frequency  Requires Only 1μF Output Capacitors  SOT-23-6 Package Applications  Communication equipment  White LED Backlight Display for PDA  Pocket PC  Handheld Devices  Cellular Phones  White LED display backlighting General Description The AF5121 is a step-up DC/DC converter specifically designed to drive up to 6 series white LEDs with constant current. Series connection of the LEDs provides identical LED currents resulting in uniform brightness and eliminates the need for ballast resistors. The AF5121 switches at 1.4MHz, allowing the use of tiny external components. A low 0.25V feedback voltage minimizes power loss in the current setting resistor for high efficiency. The OVP pin monitors the output voltage and turns off the converter wh...