LM3405,pdf datasheet (1.6MHz,

Integrated with a 1A power switch, the LM3405 is a currentmode
control switching buck regulator designed to provide a
simple, high efficiency solution for driving high power LEDs.
With a 0.205V reference voltage feedback control to minimize
power dissipation, an external resistor sets the current as
needed for driving various types of LEDs. Switching frequency
is internally set to 1.6MHz, allowing small surface mount
inductors and capacitors to be used. The LM3405 utilizes
current-mode control and internal compensation offering
ease of use and predictable, high performance regulation
over a wide range of operating conditions. Additional features
include user accessible EN/DIM pin for enabling and PWM
dimming of LEDs, thermal shutdown, cycle-by-cycle current
limit and over-current protection.