LT3797
Triple Output LED Driver
Controller
FEATURES
DESCRIPTION
The LT®3797 is a triple output DC/DC controller designed
to drive three strings of LEDs. The fixed frequency, current
mode architecture results in stable operation over a wide
range of supply and output voltages. The LT3797 includes
an integrated DC/DC converter to produce a regulated 7.5V
supply for the N-channel MOSFET gate drivers of the three
channels. This high efficiency converter enables the part to
operate from a wide input voltage range from 2.5V to 40V.
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Three Independent LED Driver Channels
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Wide Input Voltage Range: 2.5V to 40V
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V Transient Ride-Through Up to 60V
IN
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Rail-to-Rail LED Current Sense: 0V to 100V
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3000:1 PWM Dimming
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TG Drivers for PMOS LED Disconnection
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Operates in Boost, Buck Mode, Buck-Boost Mode,
SEPIC or Flyback Topology
Open-LED Protection
Short-Circuit Protected Boost Capable
Fault Flags for Independent Channels
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The LT3797 is designed so that each converter can use
the most suitable configuration to drive its LED load,
whether step-up, step-down or a combination. Two key
features enable this flexibility: first the LT3797 can sense
output current at the high side of the LED string; and
second, the voltage feedback pin, FBH, is referred to the
ISP current sensing input. The CTRL inputs provide out-
put current analog dimming capability. The TG drivers
level shift the PWM signals to drive the gates of external
LED-disconnect P-channel MOSFETs, allowing high PWM
dimming range, and providing LED overcurrent protection
and short-circuit protected boost capability.
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n
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Programmable V Undervoltage and Overvoltage
Lockout
IN
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n
n
n
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Adjustable Switching Frequency: 100kHz to 1MHz
Synchronizeable to an External Clock
CTRL Pins Provide Analog Dimming
Programmable Soft-Start
Low Profile 52-Lead 7mm x 8mm QFN and 48-Lead
Exposed Pad LQFP
APPLICATIONS
All registered trademarks and trademarks are the property of their respective owners. Protected
by U.S. Patents, including 7199560, 7321203, 7746300.
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Automotive and Industrial Lighting
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RGB Lighting
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Billboards and Large Displays
TYPICAL APPLICATION
Triple Boost LED Driver
V
IN
2.5V TO 40V
(60V TRANSIENT,
41V INTERNAL
4.7µF
×3
10µH
10µH
10µH
OVLO PROTECTION)
4.7µF
100V
×3
4.7µF
100V
×3
4.7µF
100V
×3
ISP1
250mΩ
ISN1
ISP2
250mΩ
ISN2
ISP3
250mΩ
ISN3
1A
50V
1A
50V
1A
50V
8mΩ
8mΩ
8mΩ
GATE1 SENSEP1 SENSEN1 TG1
GATE2 SENSEP2 SENSEN2 TG2
LT3797
GATE3 SENSEP3 SENSEN3 TG3 ISN1-3
ISP1-3
V
IN
1µF 100k
23.2k
EN/UVLO
FBH1-3
105k
OVLO V
REF
CTRL1-3 PWM1-3 RT
SYNC SS1-3
FLT1-3 SW1 SW2 BOOST INTV GND
CC
VC1-3
47.5k
310kHz
3.9k
6.8nF
1M
10µF
0.1µF
0.1µF
47µH
V
IN
1M
140k
3797 TA01
Rev D
1
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