Catalyst Semiconductor introduced a buck converter in a TSOT-23 package for driving high-brightness, 350 mA LEDs at up 94 percent efficiency. The CAT4201 incorporates the company's patent-pending switching control algorithm. This new architecture is said to reduce system complexity, improve efficiency and allow an external RSET control resistor to preset a regulated LED current up to 350 mA from supplies as high as 24V for inductor control and to eliminate the need for a dedicated heat sink. Built-in load dump protection 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. The switching architecture of the CAT4201 lets designers control the average current with a single external resistor for low internal power dissipation. The CAT4201 is housed in a five-lead TSOT-23 package. It is compatible with switching frequencies up to 1MHz, making it appropriate for applications requiring small-footprint, low-cost external inductors.