Features
n 3000:1 True Color PWM™ Dimming for LEDs
n Wide VIN Range: 4.5V to 60V
n Rail-to-Rail Current Sense Range: 0V to 80V
n Programmable PWM Dimming Signal Generator
n Constant Current (±3%) and Constant-Voltage
(±2%) Regulation
n Analog Dimming
n Drives LEDs in Boost, SEPIC, Inverting, Buck Mode,
Buck-Boost Mode, or Flyback Configuration
n Output Short-Circuit Protected Boost
n Open LED Protection
n Adjustable Switching Frequency: 100kHz to 1MHz
n Programmable VIN UVLO with Hysteresis
n C/10 Indication for Battery Chargers
n Low Shutdown Current: <1µA
n Thermally Enhanced 16-Lead MSOP Package
n Open LED Status Pin (LT3761)
n Frequency Synchronization (LT3761-1)
Applications
n High Voltage LED Strings >100V with Ground
Referred Current Sense
n Grounded Anode LEDs
n Accurate Current Limited Voltage Regulators
LT3761/LT3761-1
60VIN LED Controller with
Internal PWM Generator
Description
The LT®3761/LT3761-1 is a DC/DC controller designed to
operate as a constant-current source and constant-voltage
regulator. It features a programmable internal PWM dim-
ming signal. The LT3761/LT3761-1 is ideally suited for
driving high current LEDs, but also has features to make
it suitable for charging batteries and supercapacitors.
The fixed frequency, current mode architecture results in
stable operation over a wide range of supply and output
voltages. A voltage feedback pin serves as the input for
several LED protection features, and also makes it possible
for the converter to operate as a constant-voltage source.
A frequency adjust pin allows the user to program the
frequency from 100kHz to 1MHz to optimize efficiency,
performance or external component size. The LT3761-1
can be synchronized to an external clock.
The LT3761/LT3761-1 senses output current at the high
side or at the low side of the load. The PWM input can be
configured to self-oscillate at fixed frequency with duty
ratio programmable from 4% to 96%. When driven by
an external signal, the PWM input provides LED dimming
ratios of up to 3000:1. The CTRL input provides additional
analog dimming capability.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
True Color PWM is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners. Protected by U.S. Patents including 7199560, 7321203.
Typical Application
94% Efficient Boost LED Driver for Automotive
Headlamp with 25:1 Internal PWM Dimming
VIN
8V TO
60V
10µH
2.2µF
×2
499k
90.9k
INTVCC
1M
140k
VIN
EN/UVLO
VREF
GATE
SENSE
LT3761
CTRL
GND
2.2µF 1M
×4
10mΩ
16.9k
0.25Ω
100k
DIM
124k
0.01µF
47nF
300Hz
FB
OPENLED
DIM/SS
ISP
ISN
PWM
PWMOUT
VC RT INTVCC
5.1k
4.7nF
28.7k
350kHz
INTVCC
1µF
1A
60W
LED
STRING
PWM Dimming Waveforms at
Various DIM Voltage Settings
ILED
1A/DIV
VDIM = 7.7V
DCPWM = 96%
VDIM = 4V
DCPWM = 50%
VDIM = 1.5V
DCPWM = 10%
VDIM = 0.4V
DCPWM = 4.3%
0.5ms/DIV
37611 TA01b
37611 TA01a
For more information www.linear.com/LT3761
37611fa
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