LTC 60-V LED controller integrates PWM generator for boost, buck, or buck-boost high-current LED applications

Date
12/06/2012

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Click image to enlarge: 60-V LED controller with internal PWM generator

Linear Technology has announced the LT3761, a 60-V DC-DC controller designed to operate as a constant-current source and constant-voltage regulator. Its internal PWM dimming generator makes it well suited for driving high-current LEDs, but it also has features making it suitable for charging batteries and supercapacitors. The LT3761's 4.5- to 60-V input-voltage range makes it well suited 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 W. 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 is a compact high-power LED driver. The LT3761 has an internal PWM generator that provides 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 provide 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 makes it possible for the converter to operate as a constant-voltage source for charging applications. 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 each. All pricing is based on 1,000-piece quantities and all versions are available from stock. Summary of Features: LT3761

  • 3,000:1 PWM dimming for LEDs
  • Wide VIN range: 4.5 to 60 V
  • Rail-to-rail current sense range: 0 to 80 V
  • Programmable PWM dimming signal generator
  • Constant current (3%) and constant-voltage (2%) regulation
  • Analog dimming
  • Drives LEDs in boost, sepic, inverting, buck mode, buck-boost mode, or flyback configurations
  • Output short-circuit protected boost
  • Open LED protection and reporting
  • Adjustable switching frequency: 100 kHz to 1 MHz
  • Programmable VIN UVLO with hysteresis
  • C/10 indication for battery chargers
  • Low shutdown current: < 1 μA
  • Thermally enhanced 16-lead MSOP package
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