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LT3491 Datasheet, PDF (1/16 Pages) Linear Technology – White LED Driver with Integrated Schottky in SC70 and 2mm × 2mm DFN | |||
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LT3491
White LED Driver with
Integrated Schottky in SC70
and 2mm à 2mm DFN
FEATURES
DESCRIPTIO
â Drives Up to Six White LEDs from a 3V Supply
â High Side Sense Allows âOne Wire Current Sourceâ
â Internal Schottky Diode
â One Pin Dimming and Shutdown
â 27V Open LED Protection
â 2.3MHz Switching Frequency
â ±5% Reference Accuracy
â VIN Range: 2.5V to 12V
â Requires Only 1µF Output Capacitor
â Wide 300:1 True Color PWMTM Dimming Range
â 8-Lead SC70 Package
â Low Profile 6-Lead DFN Package
(2mm à 2mm à 0.75mm)
U
APPLICATIO S
â Cellular Phones
â PDAs, Handheld Computers
â Digital Cameras
â MP3 Players
â GPS Receivers
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 âone wire current source;â 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.
The 2.3MHz switching frequency allows the use of tiny
inductors and capacitors. A single pin performs both
shutdown and accurate LED dimming control. Few exter-
nal components are needed: open-LED protection and the
Schottky diode are all contained inside the tiny SC70 and
2mm à 2mm DFN packages. With such a high level of
integration, the LT3491 provides a high efficiency LED
driver solution in the smallest of spaces.
, LTC, LT and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
TYPICAL APPLICATIO
VIN
3V TO 5V
Li-Ion Driver for Four White LEDs
SHUTDOWN AND
DIMMING CONTROL
L1
10µH
C1
1µF
CTRL
VIN
CAP
LT3491
SW
LED
GND
RSENSE
10â¦
C2
1µF
C1: TAIYO YUDEN LMK212BJ105MD
C2: TAIYO YUDEN GMK316BJ105ML
L1: MURATA LQH32CN100
3491 TA01a
Efficiency
80
VIN = 3.6V
75 4 LEDs
70
65
60
55
50
45
40
0
5
10
15
20
LED CURRENT (mA)
3491 TA01b
3491fa
1
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