DC/DC Converter drives high-current LEDs.

Press Release Summary:

With input voltage range of 4.5-80 V, Model LT3956 operates as constant-current and constant-voltage regulator. Device uses internal N-channel MOSFET and can drive up to eighteen 350 mA white LEDs from nominal 12 V input, delivering in excess of 25 W. Converter incorporates high-side current sense, enabling use in boost, buck, buck-boost or SEPIC and flyback topologies. Housed in 5 x 6 mm QFN package, IC features adjustable frequency of 100 kHz to 1 MHz and efficiencies over 94% in boost mode.

Original Press Release:

80VIN/80VOUT, Constant Voltage, Constant-Current DC/DC Converter

MILPITAS, CA - Linear Technology announces the LT3956, an 80V high-side current sense DC/DC converter designed to operate as a constant-current and constant-voltage regulator. It is ideal for driving high current LEDs as well as charging batteries and supercaps. Its 4.5V to 80V input voltage range makes it ideal for a wide variety of applications, including automotive, industrial and architectural lighting. The LT3956 uses an internal N-channel MOSFET and can drive up to eighteen 350mA white LEDs from a nominal 12V input, delivering in excess of 25 Watts. It incorporates a high-side current sense, enabling use in boost, buck, buck-boost or SEPIC and flyback topologies. The LT3956 delivers efficiencies of over 94% in boost mode, eliminating the 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 5mm x 6mm QFN package, the LT3956 offers a highly compact 25 Watt LED driver solution.

The LT3956 uses True Color PWM(TM) dimming, delivering constant LED color with dimming ranges up to 3,000:1. For less demanding dimming requirements, the CTRL pin provides a 10:1 analog dimming range. The LT3956's fixed frequency, current mode architecture ensures 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, enabling the converter to operate as a constant-voltage source.

The LT3956EUHE is available in a 36-pin 5mm x 6mm QFN package, priced starting at $3.50 each in 1,000-piece quantities. An extended temperature I-grade version, the LT3956IUHE, is priced at $4.12 each, in 1,000-piece quantities. Both versions are available from stock. For more information, visit www.linear.com/pr/3956.

Summary Features LT3956

- 3000:1 True Color PWM(TM) Dimming

- Wide Input Voltage Range: 4.5V to 80V

- Output Voltage Up to 80V

- Internal 3.3A/84V Switch

- Constant-Current & Constant-Voltage Regulation

- 250mV High Side Current Sense

- Drives LEDs in Boost, Buck Mode, Buck-Boost Mode, SEPIC or Flyback Topology

- Adjustable Frequency: 100kHz to 1MHz

- Open LED Protection

- Programmable Undervoltage Lockout with Hysteresis

- Constant-Voltage Loop Status Pin

- PWM Disconnect Switch Driver

- CTRL Pin Adjusts High Side Current Sense Threshold

- Low Shutdown Current: <1µA

- Programmable Soft-Start

- Available in the 36-Lead (5mm × 6mm) QFN Package

About Linear Technology

Linear Technology Corporation, a manufacturer of high performance linear integrated circuits, was founded in 1981, became a public company in 1986 and joined the S&P 500 index of major public companies in 2000. Linear Technology products include high performance amplifiers, comparators, voltage references, monolithic filters, linear regulators, DC-DC converters, battery chargers, data converters, communications interface circuits, RF signal conditioning circuits, µModule® products, and many other analog functions. Applications for Linear Technology's high performance circuits include telecommunications, cellular telephones, networking products such as optical switches, notebook and desktop computers, computer peripherals, video/multimedia, industrial instrumentation, security monitoring devices, high-end consumer products such as digital cameras and MP3 players, complex medical devices, automotive electronics, factory automation, process control, and military and space systems.
LT, LTC, LTM, µModule and are registered trademarks and True Color PWM is a trademark of Linear Technology Corp. All other trademarks are the property of their respective owners.

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