General Description

The RT9271 is a step-up DC/DC converter specifically designed to drive white LEDs with a constant current. The device can drive one to three LEDs in series from a Li-Ion cell. Series connection of the LEDs providesidentical LED currents resulting in uniform brightness and eliminating the need for ballast resistors. The RT9271 switches at 1.1 MHz, allowing the use of tiny external components. The input and output capacitor can be as small as 1uF, saving space and cost versus alternative solutions. A low 0.25V feedback voltage minimizes power loss in the current

setting resistor for better efficiency.

Features

Inherently Matched LED Current

Up to 80mA Output Current @ VOUT< 12V

High Efficiency : 85% Typical

Drives Up to Three LEDs from 2.8V Supply

20V Internal Switch

Fast 1.1 MHz Switching Frequency

Uses Tiny 1 mm Height Inductors

Requires Only 1uF Output Capacitor

Low Profile SOT-23-6 Package

Optional 15V Over Voltage Protection

RoHS Compliant and 100% Lead (Pb)-Free



Applications

Mobile Phone

Digital Still Camera

PDAs, Handheld Computers

MP3 Players

GPS Receivers