LM3405_07 Datasheet, PDF (1/20 Pages) National Semiconductor (TI) – 1.6MHz, 1A Constant Current Buck Regulator for Powering LEDs

February 2007
LM3405
1.6MHz, 1A Constant Current Buck Regulator for Powering
LEDs
General Description
Integrated with a 1A power switch, the LM3405 is a current-
mode 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 frequen-
cy 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.
Features
■ ^V_IN ^{operating range of 3V to 15V}
■ ^{Thin SOT23-6 package}
■ ^{1.6MHz switching frequency}
■ ^{300mΩ NMOS switch}
■ ^{40nA shutdown current at V}_IN ^{= 5V}
■ ^{EN/DIM input for enabling and PWM dimming of LEDs}
■ ^{Internally compensated current-mode control}
■ ^{Cycle-by-cycle current limit}
■ ^{Input voltage UVLO}
■ ^{Over-current protection}
■ ^{Thermal shutdown}
Applications
■ ^{LED Driver}
■ ^{Constant Current Source}
■ ^{Industrial Lighting}
■ ^{LED Flashlights}
Typical Application Circuit
Efficiency vs LED Current (V_IN = 5V)
20178901
20178971
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