LM3405A_08 Datasheet, PDF (1/20 Pages) National Semiconductor (TI) – 1.6MHz, 1A Constant Current Buck LED Driver with Internal Compensation in Tiny SOT23 and eMSOP Package

October 23, 2008
LM3405A
1.6MHz, 1A Constant Current Buck LED Driver with Internal
Compensation in Tiny SOT23 and eMSOP Package
General Description
The LM3405A is a 1A constant current buck LED driver de-
signed 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
LM3405A utilizes current-mode control and internal compen-
sation offering ease of use and predictable, high performance
regulation over a wide range of operating conditions. With a
maximum input voltage of 22V, it can drive up to 5 High-
Brightness LEDs in series at 1A forward current, with the
single LED forward voltage of approximately 3.7V. 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 22V}
■ ^{Drives up to 5 High-Brightness LEDs in series at 1A}
■ ^{Thin SOT23-6 package & eMSOP8 with exposed DAP}
■ ^{1.6MHz switching frequency}
■ ^{EN/DIM input for enabling and PWM dimming of LEDs}
■ ^{300mΩ NMOS switch}
■ ^{40nA shutdown current at V}_IN ^{= 5V}
■ ^{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}
■ ^{LED Lightbulbs}
Typical Application Circuit
Efficiency vs LED Current (V_IN = 12V)
30015201
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