LT3797_15 Datasheet, PDF (1/36 Pages) Linear Technology – Triple Output LED Driver Controller

FEATURES
n _{Three Independent LED Driver Channels}
n _{Wide Input Voltage Range: 2.5V to 40V}
n _{VIN Transient Ride-Through Up to 60V}
n _{Rail-to-Rail LED Current Sense: 0V to 100V}
n _{3000:1 PWM Dimming}
n _{TG Drivers for PMOS LED Disconnection}
n _{Operates in Boost, Buck Mode, Buck-Boost Mode,}
SEPIC or Flyback Topology
n _{Open-LED Protection}
n _{Short-Circuit Protected Boost Capable}
n _{Fault Flags for Independent Channels}
n _{Programmable VIN Undervoltage and Overvoltage}
Lockout
n _{Adjustable Switching Frequency: 100kHz to 1MHz}
n _{Synchronizeable to an External Clock}
n _{CTRL Pins Provide Analog Dimming}
n _{Programmable Soft-Start}
n _{52-Lead QFN Package}
APPLICATIONS
n _{Automotive and Industrial Lighting}
n _{RGB Lighting}
n _{Billboards and Large Displays}
LT3797
Triple Output LED Driver
Controller
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.
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 output 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.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
Protected by U.S. Patents, including 7199560, 7321203, 7746300.
TYPICAL APPLICATION
V_IN
2.5V TO 40V
(60V TRANSIENT,
41V INTERNAL
OVLO PROTECTION)
4.7µF
×3
Triple Boost LED Driver
10µH
ISP1
250mΩ
ISN1
4.7µF
100V
×2
10µH
ISP2
250mΩ
ISN2
4.7µF
100V
×2
10µH
ISP3
250mΩ
ISN3
4.7µF
100V
×2
1A
1A
1A
0.1µF ^8mΩ
50V
0.1µF ^8mΩ
50V
0.1µF ^8mΩ
50V
GATE1 SENSEP1 SENSEN1 TG1
V_IN
1µF 47.5k
GATE2 SENSEP2 SENSEN2 TG2
LT3797
GATE3 SENSEP3 SENSEN3 TG3 ISN1-3
ISP1-3
20.5k
EN/UVLO
FBH1-3
49.9k
OVLO V_REF CTRL1-3 PWM1-3 RT SYNC SS1-3 FLT1-3 SW1 SW2 BOOST INTV_CC GND
VC1-3
V_IN
487k
75k
48.7k
300kHz
0.1µF
47µH 10µF
0.1µF
4.7k
1M
10nF
3797 TA01
For more information www.linear.com/LT3797
3797f
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