LT3517
Full-Featured LED Driver
with 1.5A Switch Current
FEATURES
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DESCRIPTION
The LT
®
3517 is a current mode DC/DC converter with an
internal 1.5A, 45V switch specifically designed to drive
LEDs. The LT3517 operates as a LED driver in boost,
buck mode and buck-boost mode. It combines a tradi-
tional voltage loop and a unique current loop to operate
as a constant-current source or constant-voltage source.
Programmable switching frequency allows optimization of
the external components for efficiency or component size.
The switching frequency of LT3517 can be synchronized
to an external clock signal. The LED current is externally
programmable with a 100mV sense resistor. The external
PWM input provides up to 5000:1 LED dimming. The CTRL
pin provides further 10:1 dimming ratio.
The LT3517 is available in the tiny footprint 16-Lead QFN
(4mm × 4mm) and the16-Pin TSSOP packages. The LT3517
provides a complete solution for both constant-voltage
and constant-current applications.
, 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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5000:1 True Color PWM
TM
Dimming Ratio
1.5A, 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
1A Buck Mode LED Driver
100
PV
IN
24V
100mΩ
2.2μF
ISP
V
IN
SHDN
LT3517
V
REF
PWM
CTRL
PWM
FB
SS
50
40
0
16.9k
1MHz
0.1μF
3517 TA01a
Efficiency
10μF
90
EFFICIENCY (%)
CTRL = V
REF
1A
15μH
ISN
TG
SW
80
70
60
V
IN
3.3V
2.2μF
R
T
SYNC
TGEN V
REF
V
C
GND
0.1μF
20
40
60
80
PWM DUTY CYCLE (%)
100
3517 TA01b
3517fa
1
LINER [ LINEAR TECHNOLOGY ]
