Powering and Dimming High-Brightness LEDs with the LM3405 Constant- Current Buck Regulator

The LM3405 is a 1A, constant-current buck regulator designed to provide a simple, highly-efficient solution for powering LEDs with the highest power density. The low-feedback reference voltage of 205 mV (typical) allows the use of LEDs with large forward voltages. The LM3405 LED driver comes with an integrated 1A high-side power switch, internal current limit, over-voltage protection and thermal shutdown. The LM3405 driver utilizes current mode control with internal compensation offering ease-of-use and predictable, high-performance regulation over a wide range of operating conditions. This article describes a few of the many application solutions for the LM3405 LED driver. The LM3405 device is offered in a 6-pin Thin-SOT (TSOT) package and operates at an internal switching frequency of 1.6 MHz, allowing the use of smallvalue inductors, thereby saving board space.