Linear synchronous buck-boost high-power white LED driver

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Date Announced: 29 Mar 2006

Synchronous Buck-Boost High Power White LED Driver Delivers Up to 1A from a 3mm x 3mm DFN

Linear Technology has announced the LTC3454, a synchronous buck-boost DC/DC converter optimized for driving a single high current white LED at up to 1A from a single Li-Ion battery input. The regulator operates automatically in either a synchronous buck, synchronous boost or buck-boost mode, depending on input voltage and LED maximum forward voltage. This is of particular importance in high current LED applications, as the LED forward voltage can vary from 2.7V to 4.9V depending on current level.

Using a proprietary architecture, efficiency of 90% can be achieved over the entire usable range of a Li-Ion battery (2.7V to 4.2V). Furthermore, the LED current is programmable to one of four levels (including shutdown) with dual current setting resistors and dual enable pins. In shutdown, the supply current is less than 1uA. A high constant operating frequency of 1MHz allows the use of a small inductor. The LTC3454 is offered in a low profile (0.75mm) thermally enhanced 10-lead (3mm x 3mm) DFN package.

The LTC3454EDD is available from stock in a 3mm x 3mm DFN package. Pricing starts at $1.95 each for 1,000-piece quantities.


Summary of Features of the LTC3454:

* High Efficiency: >90% Typical in Torch Mode, >80% in Flash Mode

* Wide VIN Range: 2.7V to 5.5V

* Up to 1A Continuous Output Current

* 3.5% LED Current Programming Accuracy

* Internal Soft-Start

* Open/Shorted LED Protection

* Constant Frequency 1MHz Operation

* Shutdown Current < 1uA

* Overtemperature Protection

* Small Thermally Enhanced 10-Lead (3mm x 3mm) DFN Package

Contact
UK and Ireland: Alastair Boyd, Linear Technology (UK) Limited Tel: +44 (0)1628 477066 E-mail: aboyd@linear.com North America and General Information: Doug Dickinson, Linear Technology Corporation Tel: (408) 432 1900 ext. 2233 E-mail: ddickinson@linear.com

E-mail:uksales@linear.com

Web Site:http://www.linear.com

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