FEATURES
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LT3591
White LED Driver with
Integrated Schottky in
3mm
×
2mm DFN
DESCRIPTION
The LT
®
3591 is a fixed frequency step-up DC/DC converter
specifically designed to drive up to ten 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.
The high switching frequency allows the use of tiny induc-
tors and capacitors. A single pin performs both shutdown
and accurate LED dimming control. Few external compo-
nents are needed: open-LED protection and the Schottky
diode are all contained inside a low profile 3mm
×
2mm
DFN package.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
True Color PWM is a trademark of Linear Technology Corporation. All other trademarks are
the property of their respective owners.
Drives Up to Ten White LEDs from a 3V Supply
High Side Sense Allows “One Wire Current Source”
Internal Schottky Diode
One Pin Dimming and Shutdown
80:1 True Color PWM
TM
Dimming Range
42V Open LED Protection
1MHz Switching Frequency
±5% Reference Accuracy
V
IN
Range: 2.5V to 12V
Requires Only 2.2µF Output Capacitor
Low Profile 8-Lead DFN Package
(3mm
×
2mm
×
0.75mm)
APPLICATIONS
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Cellular Phones
PDAs, Handheld Computers
Digital Cameras
MP3 Players
GPS Receivers
TYPICAL APPLICATION
Li-Ion Driver for Ten White LEDs
SHUTDOWN AND
DIMMING CONTROL
CTRL
EFFICIENCY (%)
V
IN
3V TO 5V
22µH
SW
GND
1µF
V
IN
LT3591
LED
2.2µF
60
CAP
R
SENSE
10Ω
80
Conversion Efficiency
V
IN
= 3.6V
10 LEDs
75
70
65
55
0
5
10
LED CURRENT (mA)
15
20
3591 TA01b
3591 TA01a
3591f
1
LINEAR [ LINEAR INTEGRATED SYSTEMS ]
