AP1521 Datasheet | Anachip

Features - Inherently Matched LED Current - Drives Up to Four LEDs from a 3.2V Supply - Drives Up to Six LEDs from a 5V Supply - High Efficiency: 84% Typical - Fast 1MHz Switching Frequency - 36V Rugged Bipolar Switch - Low Profile SOT23-5 Pb-Free Packaging - Applications - Cellular Phones - PDAs, Hand-held puters - Digital Cameras - MP3 Players - GPS Receivers - Pin Assignments Top View VIN SHDN SW VSS FB SOT23-5L - General Description The AP1521 is a step-up DC/DC converter specifically designed to drive white LEDs with a constant current. The device can drive two, three or four LEDs in series from a Li-Ion cell. Series connection of the LEDs provides identical LED currents resulting in uniform brightness and eliminates the need for ballast resistors. The AP1521 switches at 1MHz that allows the use of tiny external ponents. A low 300m V feedback voltage minimizes power loss in the current setting resistor for better efficiency. -...