LT3756/LT3756-1/LT3756-2
1
375612fb
Typical applicaTion
FeaTures
applicaTions
DescripTion
100V
IN
, 100V
OUT
LED Controller
The LT
®
3756, LT3756-1 and LT3756-2 are DC/DC control-
lers designed to operate as a constant-current source for
driving high current LEDs. They drive a low side external
N-channel power MOSFET from an internal regulated 7.15V
supply. The fixed frequency, current-mode architecture
results in stable operation over a wide range of supply
and output voltages. A ground referenced voltage FB 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 LT3756/LT3756-1/LT3756-2 sense output current at
the high side of the LED string. High side current sensing
is the most flexible scheme for driving LEDs, allowing
boost, buck mode or buck-boost mode configuration.
The PWM input provides LED dimming ratios of up to
3000:1, and the CTRL input provides additional analog
dimming capability.
94% Efficient 30W White LED Headlamp Driver
n
3000:1 True Color PWM™ Dimming
n
Wide Input Voltage Range: 6V to 100V
n
Output Voltage Up to 100V
n
Constant-Current and Constant-Voltage Regulation
n
100mV High Side Current Sense
n
Drives LEDs in Boost, Buck Mode, Buck-Boost Mode,
SEPIC or Flyback Topology
n
Adjustable Frequency: 100kHz to 1MHz
n
Open LED Protection
n
Programmable Undervoltage Lockout with Hysteresis
n
Improved Open LED Status Pin (LT3756-2)
n
Frequency Synchronization (LT3756-1)
n
PWM Disconnect Switch Driver
n
CTRL Pin Provides Analog Dimming
n
Low Shutdown Current: <1µA
n
Programmable Soft-Start
n
Thermally Enhanced 16-Lead QFN (3mm × 3mm)
and MSOP Packages
n
High Power LED Applications
n
Current Limited Constant Voltage Applications
n
Battery Charging
V
IN
LT3756-2
22µH
GNDV
C
INTV
CC
SHDN/UVLO FB
V
REF
ISP
332k
100k
INTV
CC
1M
4.7µF
0.001µF
0.01µF
V
IN
8V TO 60V
(100V TRANSIENT)
185k
10k
28.7k
375kHz
1%
4.7µF
INTV
CC
40.2k
CTRL
0.018Ω
0.27Ω
1M
14k
370mA
4.7µF
30W
LED
STRING
375612 TA01a
OPENLED
PWM
SS
RT
ISN
GATE
SENSE
PWMOUT
Efficiency vs V
IN
V
IN
(V)
0 20
80
EFFICIENCY (%)
84
88
92
96
100
40
60 80
375612 TA01b
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. 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 and 7321203.
