LT3518
Full-Featured LED Driver
with 2.3A Switch Current
FEATURES
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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-
grammable switching frequency allows optimization of the
external components for efficiency or component size. 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.
The LT3518 is available in the tiny footprint 16-Lead QFN
(4mm
×
4mm) and the 16-Pin TSSOP package. The LT3518
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.
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3000:1 True Color PWM™ Dimming Ratio
2.3A, 45V Internal Switch
100mV High Side Current Sense
Open LED Protection
Adjustable Frequency: 250kHz to 2.5MHz
Wide Input Voltage Range:
Operation from 3V to 30V
Transient Protection to 40V
Operates in Boost, Buck Mode and Buck-Boost Mode
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
APPLICATIONS
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Display Backlighting
Automotive and Avionic Lighting
Illumination
Scanners
TYPICAL APPLICATION
1.5A Buck Mode LED Driver
Efficiency
PV
IN
24V
68mΩ
2.2μF
ISP
V
IN
SHDN
LT3518
V
REF
PWM
CTRL
PWM
FB
SS
50
40
0.1μF
3518 TA01a
M1
10μF
100
CTRL = V
REF
90
1.5A
15μH
EFFICIENCY (%)
16.9k
1MHz
ISN
TG
SW
80
70
60
V
IN
3.3V
2.2μF
R
T
SYNC
TGEN V
REF
V
C
GND
0.1μF
0
20
40
60
80
PWM DUTY CYCLE (%)
100
3518 TA01b
3518fb
1
LINER [ LINEAR TECHNOLOGY ]
