32-channel 30-mA buck LED driver offers DOT correction and gray scale dimming

April 06, 2011 // By Paul Buckley
Linear Technology has introduced a 32-channel LED driver integrated with a 55 V step-down controller. The LT3746 LED driver powers up to 30 mA of LED current for each channel, which can drive up to 13 V of LEDs in series, making it ideal for applications such as large LED billboards.

Each channel has individual 6-bit dot correction current adjustment and 12-bit gray scale PWM dimming. Combined with a 0.5 µs minimum LED on-time, the LT3746 offers wide dynamic contrast ratios. Both dot correction and gray scale dimming are accessible via a serial interface in TTL/CMOS logic. The LT3746's 6 V to 55 V input voltage range makes it ideal for a wide range of input sources found in commercial and industrial designs, typically between 12 V and 48 V. The combination of minimal externals and a 5 mm x 9 mm QFN package provide a highly compact solution footprint for multichannel LED applications.     

The LT3746's internal buck controller generates an adaptive bus voltage slightly higher than the parallel LED strings to deliver efficiencies over 90%. 32 individual linear current sinks regulate and modulate individual LED strings, offering a wide range of functionality in a compact solution footprint. The LT3746 performs full diagnostics and protection against open/short LED and overtemperature faults, with the fault status sent via the serial data interface. The 30 MHz fully buffered, skew-balanced, cascadable serial interface makes the LT3746 ideal for large screen LCD dynamic backlighting as well as full color LED displays.        


The LT3746EUHH is available in a 56-lead 5mm x 9mm QFN package priced starting at $4.95 each, in 1,000-piece quantities. The extended temperature version the LT3746IUHH, or I-grade, is also available, priced starting at $5.45 each in 1,000-piece quantities.  All versions are available from stock.      

More information about the LT3746 LED driver at www.linear.com/product/LT3746