DESCRIPTION
The LT®3491 is a fixed frequency step-up DC/DC converter specifically designed to drive up to six white LEDs in series from a Li-Ion cell. Series connection of the LEDs provides identical LED currents resulting in uniform brightness and eliminating the need for ballast resistors. The device features a unique high side LED current sense that enables the part to function as a “one wire current source;” one side of the LED string can be returned to ground anywhere, allowing a simpler one wire LED connection. Traditional LED drivers use a grounded resistor to sense LED current, requiring a 2-wire connection to the LED string.

FEATURES
■ Drives Up to Six White LEDs from a 3V Supply
■ High Side Sense Allows “One Wire Current Source”
■ Internal Schottky Diode
■ One Pin Dimming and Shutdown
■ 27V Open LED Protection
■ 2.3MHz Switching Frequency
■ ±5% Reference Accuracy
■ VIN Range: 2.5V to 12V
■ Requires Only 1µF Output Capacitor
■ Wide 300:1 True Color PWMTM Dimming Range
■ 8-Lead SC70 Package
■ Low Profile 6-Lead DFN Package
   (2mm × 2mm × 0.75mm)

APPLICATIONS
■ Cellular Phones
■ PDAs, Handheld Computers
■ Digital Cameras
■ MP3 Players
■ GPS Receivers