60-V, LED controller features internal PWM generator for boost, buck or buck-boost high current LED applications

December 04, 2012 // By Paul Buckley
Linear Technology has released a 60V DC/DC controller designed to operate as a constant-current source and constant-voltage regulator.

The LT3761’s internal PWM dimming generator makes it ideal for driving high current LEDs, but it also has features making it suitable for charging batteries and supercapacitors. The device’s 4.5 V to 60 V input voltage range makes it ideal for a wide variety of applications, including automotive, industrial and architectural lighting. The LT3761 uses an external N-channel MOSFET and can drive up to fifteen 1 A white LEDs from a nominal 12 V input, delivering in excess of 50 watts. It incorporates a high-side current sense, enabling its use in boost mode, buck mode, buck-boost mode or SEPIC topologies. The LT3761 can deliver efficiencies of over 94% in the boost topology, eliminating the need for external heat sinking. A frequency adjust pin permits the user to program the frequency between 100 kHz and 1 MHz, optimizing efficiency while minimizing external component size and cost. Combined with a thermally enhanced MSOP-16 package, the LT3761 offers a compact high power LED driver solution.

The LT3761 has an internal PWM generator that delivers dimming ratios as high as 50:1 or it can utilize an external PWM signal, delivering dimming ratios 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. Output short-circuit protection and open LED protection enhance system reliability. The LT3761’s ground-referenced voltage FB 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 for charging applications.

Availability and Pricing

The LT3761EMSE is available in a thermally enhanced MSOP-16 package. Pricing starts at $3.45 each. An extended temperature version, or I grade, the LT3761IMSE, is also available, priced starting at $3.86 each.  Finally a high temperature or H grade option, the LT3761HMSE is also available, starting at $4.11