RT9271

Features:

• Inherently Matched LED Current
• High Efficiency: 85% Typical
• Drives Up to Four LEDs from 2.8V Supply
• 20V Internal Switch
• Fast 1.1 MHz Switching Frequency
• Uses Tiny 1 mm Tall Inductors
• Requires Only 1uF Output Capacitor
• Low Profile SOT-26 Package
• Optional 15V Over Voltage Protection




Application

• Mobile Phone
• Digital Still Camera
• PDAs, Handheld Computers
• MP3 Players
• GPS Receivers




Pinout






Specifications

Input Supply Voltage......... −0.3V to 7V
SW ................... −0.3V to 21V
The Other Pins ............ −0.3V to 21V
Operating Temperature Range .. 0°C to 70°C
Junction Temperature Range .. 0°C to 125°C
Storage Temperature Range ..−65°C to 150°C




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 provides identical 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.
The RT9271 is available in low profile SOT-23-6 package.