Linear's boost converter is ideal as high current LED driver

Nov. 17, 2004
Date Announced: 17 Nov 2004 Linear Technology Corporation (Milpitas, CA) announces the LT3479, a current mode, fixed frequency step-up DC/DC converter with an internal 3A, 42V switch. It operates from an input voltage range of 2.5V to 24V making it suitable for applications with input sources ranging from a single cell Li-Ion to a 20V wall adapter. Both inputs of the error amplifier are available to the user, permitting use as a boost converter or an inverter. Its 42V switch enables outputs as large as + 40V. It can also drive two high current white LEDs (in series) with current as high as 700mA from a single Li-Ion cell. In addition, its switching frequency can be programmed, via a single resistor, between 300kHz and 3.5MHz, enabling the designer to minimize external component sizes and avoid "noise critical" frequency bands in the system. A tiny/low profile inductor and ceramic capacitors keep solution footprints very compact while minimizing solution cost.The LT3479's low VCESAT switch, 0.3V at 2.5A, delivers efficiencies of up to 89%. The device features a programmable soft-start function to limit inductor current during start-up as well as inrush current protection to protect the LT3479 during shorts and line transients. The low profile (0.75mm) 14-pin, 4mm x 3mm DFN-14 package provides excellent thermal performance in a small footprint. The LT3479 is also available in a thermally enhanced 16-pin TSSOP package.Both the LT3479EDE in a 4mm x 3mm DFN-14 package and the LT3479EPE TSSOP-16E version are available from stock. Pricing for both package options starts at $3.00 each for 1,000-piece quantities.Summary of Features: LT3479* Wide Input Voltage Range: 2.5V to 24V* 3A, 42V Internal Switch* High Efficiency Power Conversion: Up to 89%* Integrated Soft-Start* Frequency Set by External Resistor: 200kHz to 3.5MHz* Device Protected Against Input Short Circuits and Hot Plugging* Low VCESAT Switch: 0.3 V at 2.5 A (Typical)* Capable of Positive and Negative Outputs* Available in Thermally Enhanced 14-Lead (4mm x 3mm) DFN-14 and 16-Lead TSSOP Packages

Doug Dickinson Tel: (408) 432 1900 ext. 2233

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