High Current Quad Output LED Driver

The LT3476 is a quad output DC/DC converter designed to operate as a constant-current source for driving high current LEDs. A fixed frequency, current mode architecture results in stable operation over a wide range of supply and output voltages. A frequency adjust pin allows the user to program switching frequency between 200kHz and 2MHz to optimize efficiency and external component size.

The LT3476 senses output current at the high side of the LED. High side current sensing is the most flexible scheme for driving LEDs, allowing buck, boost or buckboost configurations. Each current monitor threshold is trimmed to within 2.5% at the full scale of 105mV. With an external sense resistor, the user programs the output current range of each channel. Each of the four regulators is independently operated by that channel’s PWM signal. This PWM feature allows precise adjustment of the color mixing or dimming ratio of the LED source. Dimming ratios up to 1000:1 can be achieved.

Applications

* RGGB Lighting

* Automotive and Avionic Lighting

* TFT LCD Backlighting

* Constant-Current Sources

* True Color PWM™ Dimming Delivers Up to 5000:1 Dimming Ratio (In Boost Configuration)

* LED Current Regulation with High-Side Sense

* VADJ Pin Accurately Sets LED Current Sense Threshold Over Range 10mV to 120mV

* Four Independent Driver Channels with 1.5A, 36V Internal NPN Switches

* Frequency Adjust Pin: 200kHz to 2MHz

* High Efficiency Conversion = Up to 96%

* Open LED Protection

* Low Shutdown Current < 10μA

* Wide VIN Range: 2.8V to 16V

* Thermally Enhanced, 38-Lead, 5mm × 7mm QFN Package