60V, high side sense LED controller for boost, buck or buck-boost high current LED applications
(Product News, 16 Jun 2008 )
Linear Technology has announced the LT3755, a 60V, high-side current sense DC/DC converter designed to drive high current LEDs. Its 4.5V to 40V input voltage range makes it ideal for a wide variety of applications, including automotive, industrial and architectural lighting. The LT3755 uses an external N-channel MOSFET and can drive up to 14 1A white LEDs from a nominal 12V input, delivering in excess of 50 watts. It incorporates a high-side current sense, enabling it to be used in boost, buck, buck-boost or SEPIC and flyback topologies. The LT3755 can deliver efficiencies of over 94% in boost mode, eliminating any need for external heat sinking. A frequency adjust pin permits the user to program the frequency between 100kHz and 1MHz, optimizing efficiency while minimizing external component size and cost. Combined with a 3mm x 3mm QFN package, the LT3755 offers a very compact 50 watt LED driver solution.
The LT3755 uses True Color PWM™ dimming, which delivers constant LED color with dimming ranges of up to 3,000:1. For less demanding dimming requirements, the CTRL pin can be used to offer a 10:1 analog dimming range. Its fixed frequency, current mode architecture offers stable operation over a wide range of supply and output voltages. A ground referenced voltage FB pin serves as the input for several LED protection features, making it possible for the converter to operate as a constant-voltage source.
