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Optoelectronics/Displays??

Tiny buck converter powers up to seven LEDs

Posted: 30 Jul 2007 ?? ?Print Version ?Bookmark and Share

Keywords:tiny buck converters? LED driver?

CAT4201

Catalyst Semiconductor Inc. has unveiled a new family of buck converters in a TSOT-23 package optimized for driving high-brightness, 350mA LEDs at up 94 percent efficiency.

The first device in the family, CAT4201 incorporates Catalyst?s patent-pending switching control algorithm. This new architecture reduces system complexity, improves efficiency and allows an external RSET control resistor to preset a regulated LED current up to 350mA from supplies up to 24V, to provide better inductor control and eliminate the need for a dedicated heat sink.

The CAT4201 buck converter offers a simpler and smaller alternative to linear regulators for driving high-brightness LEDs in step-down applications, eliminating the need for heatsinks. Built-in load dump protection also allows transients of 40V to be safely handled, fully optimizing the CAT4201 for automotive indicator and illumination lighting applications, including turn signal, brake and map reading lights.

Traditionally, LEDs from 12V or 24V buses have been driven by linear regulators. Such generates a significant amount of heat, resulting in the need for a dedicated heat sink and thus, a very large TO263 package.

The patent-pending switching architecture of the CAT4201 allows designers to easily control the average current with a single external resistor. This results in extremely low internal power dissipation, allowing the CAT4201 to be housed in a tiny, 5-lead TSOT-23 package without the need for a dedicated heat sink. Moreover, the device is compatible with switching frequencies up to 1MHz, making it well suited for applications requiring small-footprint, low-cost external inductors.

CAT4201 can drive one 1W LED from a 6V supply or up to seven LEDs in series from a 24V supply. A dedicated enable control using minimal input current allows the load to be disabled and placed into a zero current shutdown mode, eliminating battery drain when not in use. The device also has short circuit and thermal overload protection.

CAT4201 is priced at 72 cents each in 10,000 piece quantities. Samples are available now. Projected lead-time for production quantities is currently 6 to 8 weeks ARO.




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