LT3797
Triple Output LED Driver
Controller
FEATURES DESCRIPTION
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Three Independent LED Driver Channels
The LT 3797 is a triple output DC/DC controller designed
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Wide Input Voltage Range: 2.5V to 40V
to drive three strings of LEDs. The fixed frequency, current
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V Transient Ride-Through Up to 60V
mode architecture results in stable operation over a wide
IN
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Rail-to-Rail LED Current Sense: 0V to 100V
range of supply and output voltages. The LT3797 includes
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3000:1 PWM Dimming
an integrated DC/DC converter to produce a regulated 7.5V
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TG Drivers for PMOS LED Disconnection
supply for the N-channel MOSFET gate drivers of the three
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Operates in Boost, Buck Mode, Buck-Boost Mode,
channels. This high efficiency converter enables the part to
SEPIC or Flyback Topology
operate from a wide input voltage range from 2.5V to 40V.
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Open-LED Protection
The LT3797 is designed so that each converter can use
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Short-Circuit Protected Boost Capable
the most suitable configuration to drive its LED load,
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Fault Flags for Independent Channels
whether step-up, step-down or a combination. Two key
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Programmable V Undervoltage and Overvoltage
IN
features enable this flexibility: first the LT3797 can sense
Lockout
output current at the high side of the LED string; and
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Adjustable Switching Frequency: 100kHz to 1MHz
second, the voltage feedback pin, FBH, is referred to the
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Synchronizeable to an External Clock
ISP current sensing input. The CTRL inputs provide out-
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CTRL Pins Provide Analog Dimming
put current analog dimming capability. The TG drivers
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Programmable Soft-Start
level shift the PWM signals to drive the gates of external
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Low Profile 52-Lead 7mm x 8mm QFN and 48-Lead
LED-disconnect P-channel MOSFETs, allowing high PWM
Exposed Pad LQFP
dimming range, and providing LED overcurrent protection
APPLICATIONS
and short-circuit protected boost capability.
All registered trademarks and trademarks are the property of their respective owners. Protected
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Automotive and Industrial Lighting
by U.S. Patents, including 7199560, 7321203, 7746300.
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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
4.7F
(60V TRANSIENT,
3
10H 10H 10H
41V INTERNAL
OVLO PROTECTION)
4.7F 4.7F 4.7F
ISP1 ISP2 ISP3
100V 100V 100V
3 3 3
250m 250m 250m
ISN1 ISN2 ISN3
1A 1A 1A
50V 50V 50V
8m 8m 8m
GATE1 SENSEP1 SENSEN1 TG1 GATE2 SENSEP2 SENSEN2 TG2 GATE3 SENSEP3 SENSEN3 TG3 ISN1-3
V ISP1-3
IN
1F 100k 23.2k
LT3797
EN/UVLO FBH1-3
OVLO V CTRL1-3 PWM1-3 RT SYNC SS1-3 FLT1-3 SW1 SW2 BOOST INTV GND VC1-3
105k
REF CC
47.5k
3.9k 1M
0.1F 47H 10F
310kHz
V
IN
0.1F 6.8nF
1M
140k
3797 TA01
Rev C
1
Document Feedback For more information www.analog.comLT3797
ABSOLUTE MAXIMUM RATINGS
(Note 1)
V , EN/UVLO ............................................................60V RT ............................................................................1.5V
IN
INTV , SYNC, OVLO, PWM1, PWM2, PWM3 ............8V SENSEP1, SENSEP2, SENSEP3, SENSEN1,
CC
ISN1 .......................................................ISP1-1.5V, 100V SENSEN2, SENSEN3, .............................................0.3V
ISN2 .......................................................ISP2-1.5V, 100V SW1, SW2, BOOST, TG1, TG2, TG3, GATE1,
ISN3 .......................................................ISP3-1.5V, 100V GATE2, GATE3 .................................................. (Note 2)
FBH1 ...................................................... ISP1 6V, 100V Operating Ambient Temperature Range
FBH2 ...................................................... ISP2 6V, 100V (Note 3) ...................................................... 40 to 125C
FBH3 ...................................................... ISP3 6V, 100V Maximum Junction Temperature .......................... 125C
VC1, VC2, VC3, V , SS1, SS2, SS3 ..........................3V Storage Temperature Range .................. 65C to 150C
REF
CTRL1, CTRL2, CTRL3, FLT1, FLT2, FLT3...................12V
PIN CONFIGURATION
TOP VIEW
TOP VIEW
52 51 50 49 48 47 46 45 44 43 42 41
FLT1 1 40 VC3
FLT2 2
FLT3 3 38 FBH3
PWM1 ISP3
4 37
FLT1 1 36 VC3
FLT2 2 35 FBH3
PWM2 ISN3
5 36
FLT3 3 34 ISP3
PWM3 6 35 TG3
PWM1 4 33 ISN3
PWM2 5 32 TG3
V 7
REF
53
PWM3 6 49 31 NC
GND
CTRL1 8 33 TG2
V 7 GND 30 TG2
REF
CTRL1 8 29 ISN2
CTRL2 9 32 ISN2
CTRL2 9 28 ISP2
CTRL3 31 ISP2
10
CTRL3 10 27 FBH2
RT 11 26 VC2
RT 11 30 FBH2
SYNC 12 25 SS2
SYNC 12
28 VC2
TG1 14 27 SS2
15 16 17 19 20 21 22 23 24 25 26
LXE PACKAGE
48-LEAD (7mm 7mm) PLASTIC LQFP
UKG PACKAGE
VARIATION: UKG52(47) = 19C/W
JA
52-LEAD (7mm 8mm) PLASTIC QFN EXPOSED PAD (PIN 49) IS GND, MUST BE SOLDERED TO PCB
= 28C/W
JA
EXPOSED PAD (PIN 53) IS GND, MUST BE SOLDERED TO PCB
Rev C
2
For more information www.analog.com
ISN1 OVLO
ISP1
EN/UVLO
FBH1 V
IN
SW1
VC1 BOOST
SS1 SW2
SENSEN1
INTV
CC
SENSEP1 INTV
CC
GATE1 GATE3
GATE2 SENSEP3
SENSEP2 SENSEN3
SENSEN2
SS3
48 OVLO
TG1 13
47 ENUVLO
ISN1 14
46 V
ISP1 15
IN
45 SW1
FBH1 16
44 BOOST
VC1 17
43 SW2
SS1 18
42 INTV
SENSEN1 19
CC
41 INTV
SENSEP1 20
CC
40 GATE3
GATE1 21
39 SENSEP3
GATE2 22
38 SENSEN3
SENSEP2 23
37 SS3
SENSEN2 24