LT3518
Full-Featured LED Driver
with 2.3A Switch Current
FEATURES
DESCRIPTION
The LT®3518 is a current mode DC/DC converter with an
internal 2.3A, 45V switch specifically designed to drive
LEDs. The LT3518 operates as a LED driver in boost, buck
mode and buck-boost mode. It combines a traditional
voltage loop and a unique current loop to operate as a
constant-current source or constant-voltage source. Pro-
grammableswitchingfrequencyallowsoptimizationofthe
externalcomponentsforefficiencyorcomponentsize.The
switching frequency of the LT3518 can be synchronized
to an external clock signal. The LED current is externally
programmable with a 100mV sense resistor. The external
PWM input provides 3000:1 LED dimming. The CTRL pin
provides further 10:1 dimming ratio.
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3000:1 True Color PWM™ Dimming Ratio
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2.3A, 45V Internal Switch
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100mV High Side Current Sense
Open LED Protection
Adjustable Frequency: 250kHz to 2.5MHz
Wide Input Voltage Range:
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Operation from 3V to 30V
Transient Protection to 40V
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Operates in Boost, Buck Mode and Buck-Boost Mode
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Gate Driver for PMOS LED Disconnect*
Constant-Current and Constant-Voltage Regulation
CTRL Pin Provides 10:1 Analog Dimming
Low Shutdown Current: <1μA
Available in (4mm × 4mm) 16-Lead QFN and 16-Pin
TSSOP Packages
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The LT3518 is available in the tiny footprint 16-Lead QFN
(4mm×4mm)andthe16-PinTSSOPpackage.TheLT3518
provides a complete solution for both constant-voltage
and constant-current applications.
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. True Color
PWM is a trademark of Linear Technology Corporation. Patent Pending. All other trademarks are
the property of their respective owners. *Patents Pending.
APPLICATIONS
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Display Backlighting
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Automotive and Avionic Lighting
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Illumination
Scanners
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TYPICAL APPLICATION
1.5A Buck Mode LED Driver
Efficiency
100
10μF
68mΩ
M1
CTRL = V
REF
PV
IN
24V
90
2.2μF
1.5A
15μH
80
70
ISP
ISN TG
V
IN
V
SW
IN
3.3V
2.2μF
SHDN
LT3518
V
60
50
40
CTRL
PWM
FB
REF
PWM
SS
SYNC
TGEN V
R
T
GND
V
REF
C
16.9k
1MHz
0
20
40
60
80
100
0.1μF
0.1μF
PWM DUTY CYCLE (%)
3518 TA01a
3518 TA01b
3518fb
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