RT9271
White LED Step-Up Converter in Tiny Package
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 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.
Features
Inherently Matched LED Current
Up to 80mA Output Current @ V
OUT
< 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
Ordering Information
RT9271
Package Type
B : SOT-23-5
E : SOT-23-6
Operating Temperature Range
P : Pb Free with Commercial Standard
G : Green (Halogen Free with Commer-
cial Standard)
Pin Configurations
(TOP VIEW)
VCC
5
1
LX
2
GND
EN
4
3
FB
VCC OVP
6
1
LX
5
2
GND
EN
4
3
FB
Note :
RichTek Pb-free and Green products are :
RoHS compliant and compatible with the current require-
ments of IPC/JEDEC J-STD-020.
Suitable for use in SnPb or Pb-free soldering processes.
100% matte tin (Sn) plating.
SOT-23-5
SOT-23-6
Marking Information
For marking information, contact our sales representative
directly or through a RichTek distributor located in your
area, otherwise visit our website for detail.
Note
: There is no pin1 indicator on top mark for
SOT-23-6
type, and pin1 will be lower left pin when reading top mark
from left to right.
DS9271-13 March 2007
www.richtek.com
1
RICHTEK [ RICHTEK TECHNOLOGY CORPORATION ]
