Datasheet LT3761A (Analog Devices)

LT3761A 60VIN LED Controller with Internal PWM Generator
FeaTures DescripTion
n
3000:1 True Color PWM™ Dimming for LEDs
The LT®3761A is a DC/DC controller designed to operate as n
Wide VIN Range: 4.5V to 60V
a constant-current source and constant-voltage regulator. n
Rail-to-Rail Current Sense Range: 0V to 80V
It features a programmable internal PWM dimming signal. n
Programmable PWM Dimming Signal Generator
The LT3761A is ideally suited for driving high current LEDs, n
Constant Current (±3%) and Constant-Voltage
but also has features to make it suitable for charging bat-
(±2%) Regulation
teries and supercapacitors. The fixed frequency, current n
Analog Dimming
mode architecture results in stable operation over a wide n Drives LEDs in Boost, SEPIC, Inverting, Buck Mode, range of supply and output voltages. A voltage feedback Buck-Boost Mode, or Flyback Configuration pin serves as the input for several LED protection features, n Output Short-Circuit Protected Boost and also makes it possible for the converter to operate n Open LED Protection and Reporting as a constant-voltage source. A frequency adjust pin n Adjustable Switching Frequency: 100kHz to 1MHz allows the user to program the frequency from 100kHz n Programmable VIN UVLO with Hysteresis to 1MHz to optimize efficiency, performance or external n C/10 Indication for Battery Chargers component size. n Low Shutdown Current: <1µA The LT3761A senses output current at the high side or at n Thermally Enhanced 16-Lead MSOP Package the low side of the load. The PWM input can be configured
applicaTions
to self-oscillate at fixed frequency with duty ratio program- mable from 4% to 96%.
The LT3761A offers improved
n High Voltage LED Strings >100V with Ground
accuracy of internal PWM dimming over LT3761.
When Referred Current Sense driven by an external signal, the PWM input provides LED n Grounded Anode LEDs dimming ratios of up to 3000:1. The CTRL input provides n Battery and SuperCap Chargers additional analog dimming capability. n L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and Accurate Current Limited Voltage Regulators 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 PWM Dimming Waveforms at
V 10µH IN 8V TO
Various DIM Voltage Settings
60V 2.2µF 499k ×2 VIN 1M EN/UVLO GATE 2.2µF 0.25Ω 1A V ×4 REF V 90.9k SENSE DIM = 7.7V DC 1M PWM = 96% LT3761A 10mΩ 16.9k CTRL VDIM = 4V INTV DC CC 140k GND PWM = 50% ILED 100k V FB 1A/DIV DIM = 1.5V DCPWM = 10% ISP 60W OPENLED LED DIM DIM/SS ISN V STRING DIM = 0.4V 140k DC PWM PWMOUT PWM = 4.3% 0.01µF VC RT INTVCC 0.5ms/DIV 3761A TA01b 47nF 5.1k 28.7k INTVCC 300Hz 350kHz 4.7nF 1µF 3761A TA01a 3761af For more information www.linear.com/LT3761A 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 Typical Application Related Parts Features Applications Typical Application Description Absolute Maximum Ratings Order Information Electrical Characteristics Pin Configuration Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Applications Package Description Typical Application Related Parts