LT3756-2_15 Datasheet, PDF (1/24 Pages) Linear Technology – 100VIN, 100VOUT LED Controller

LT3756/LT3756-1/LT3756-2
100V_IN, 100V_OUT
LED Controller
Features
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
Applications
n _{High Power LED Applications}
n _{Current Limited Constant Voltage Applications}
n _{Battery Charging}
Description
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.
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.
Typical Application
94% Efficient 30W White LED Headlamp Driver
V_IN
8V TO 60V
(100V TRANSIENT)
22µH
4.7µF 1M
V_IN
1M
SHDN/UVLO
FB
185k
V_REF
ISP
332k
LT3756-2
CTRL
14k
0.27Ω _370mA
INTV_CC
40.2k
ISN
GATE
100k
SENSE
OPENLED
PWM
0.018Ω
SS
RT
PWMOUT
0.01µF _28.7k VC
GND INTV_CC
375kHz
1%
10k
INTV_CC
0.001µF
4.7µF
4.7µF
30W
LED
STRING
375612 TA01a
100
96
92
88
84
80
0
Efficiency vs V_IN
20
40
60
80
V_IN (V)
375612 TA01b
375612fb