Features

• Ideal for Driving Up to 40A LEDs
• Up to 3000:1 PWM Dimming
• 20:1 Analog Dimming
• ±3% Current Regulation Accuracy
• ±3% Voltage Regulation Accuracy
• Unique Inverting Buck-Boost Topology Allows Grounded Heat Sink to Be Used for RGB LEDs
• 3.3V to 36V Input Voltage Range
• Peak Current Mode with DC LED Current Sensing
• Open and Shorted LED Protection and Fault Reporting
• Floating LED Driver Allows Single Power Solution to Drive Multicolor LEDs or Single LED with Three Different Regulated Currents
• Thermally Enhanced 5mm × 6mm QFN 36-Lead Package

Typical Application

Description

The LT®3744 is a fixed frequency synchronous step-down DC/DC controller designed to drive a LED load at up to 20A continuous or 40A pulsed. The peak current mode controller will maintain ±3% LED current regulation over a wide output voltage range, from VEE to V_IN. By allowing VEE to float to negative voltages, several LEDs in series can be driven from a single Li-Ion battery with a simple, single step-down output stage. PWM dimming is achieved with the PWM pins. The regulated LED current is set with analog voltages at the CTRL pins. Regulated voltage and overvoltage protection are set with a voltage divider from the output to the FB pin. The switching frequency is programmable from 100kHz to 1MHz through an external resistor on the RT pin.

Additional features include an accurate external reference voltage, a control input for thermally derating regulation current, an accurate EN/UVLO pin, an open-drain output fault flag, OVLO, frequency synchronization, and thermal shutdown.