Datasheet LT3761, LT3761-1 (Analog Devices)

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