LED controller includes internal PWM generator

Linear Technology Corp. introduces the LT3761, a dc/dc controller designed to operate as a constant-current source and constant-voltage regulator. It also features a programmable internal PWM dimming signal. The LT3761 is well suited for driving high current LEDs, but also has features that 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 100 kHz to 1 MHz to optimize efficiency, performance, or external component size.

The LT3761 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 3,000:1. The CTRL input provides additional analog dimming capability.

Applications include:

High-voltage LED strings >100 V with ground referred current sense
Grounded anode LEDs
Battery and SuperCap chargers
Accurate current limited voltage regulators

Features:

3,000:1 True Color PWM Dimming for LEDs
Wide VIN Range: 4.5 to 60 V
Rail-to-Rail Current Sense Range: 0 to 80 V
Programmable PWM Dimming Signal Generator
Constant Current (±3%) and Constant-Voltage (±2%) Regulation
Analog Dimming
Drives LEDs in Boost, SEPIC, Inverting, Buck Mode, Buck-Boost Mode, or Flyback Configuration
Output Short-Circuit Protected Boost
Open LED Protection and Reporting
Adjustable Switching Frequency: 100 kHz to 1 MHz
Programmable VIN UVLO with Hysteresis
C/10 Indication for Battery Chargers
Low Shutdown Current: <1 μA
Thermally Enhanced 16-Lead MSOP Package