Delivered in a 5-lead TSOT-23 package, the CAT4201 buck converter is optimised for driving high-brightness, 350mA LEDs at up 94% efficiency. The chip incorporates Catalyst's patent-pending switching-control algorithm, which reduces system complexity, improves efficiency and allows an external RSET control resistor to preset a regulated LED current up to 350mA from supplies as high as 24V. Moreover, it provides better inductor control and eliminates the need for a dedicated heat sink. Built-in load dump protection allows transients of 40V to be handled safely; this makes the CAT4201 well-suited for automotive-indicator and illumination-lighting applications, including turn signal, brake and map-reading lights. The device is compatible with switching frequencies up to 1MHz, which enables the use of small-footprint, low-cost external inductors.