Description

The LT3761A is a DC/DC controller designed to operate as a constant-current source and constant-voltage regulator. It features a programmable internal PWM dimming signal. The LT3761A is ideally suited for driving high current LEDs, but also has features to 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 100kHz to 1MHz to optimize efficiency, performance or external component size.The LT3761A 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%. The LT3761A offers improved accuracy of internal PWM dimming over LT3761. When driven by an external signal, the PWM input provides LED dimming ratios of up to 3000:1. The CTRL input provides additional analog dimming capability. NOTES LT3761A Higher PWM Dimming Accuracy at Lower LED Current Levels LT3761-1 Frequency Synchronization LT3761 Open LED Status Pin APPLICATIONS High Voltage LED Strings >100V with Ground Referred Current Sense Grounded Anode LEDs Battery and SuperCap Chargers Accurate Current Limited Voltage Regulators