LM3405 Datasheet, PDF (1/2 Pages) National Semiconductor (TI) – 550kHz/1.6MHz 1A Constant Current Buck Regulator for Powering LEDs

ADVANCE INFORMATION
October 2006
LM3405
550kHz/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 LEDs. With a 0.2V
reference voltage feedback control to minimize power dissi-
pation, an external resistor sets the current as needed for
driving various types of LEDs. Switching frequency is inter-
nally set to 550kHz (LM3405-Y) or 1.6MHz (LM3405-X),
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 con-
ditions. Additional features include user accessible enable/
dim pin for enabling and PWM dimming of LEDs, thermal
shutdown, current limit and over voltage protection.
Features
n Thin SOT23-6 package
n 4.0V to 20V input voltage range
n 550kHz (LM3405Y) and 1.6MHz (LM3405X)
switching frequencies
n 300mΩ NMOS switch
n 30nA shutdown current
n Enable/DIM input for enabling and PWM dimming of
LEDs
n Requires only low value, ceramic capacitors
n Input voltage UVLO
n Internally compensated current mode control
n Thermal shutdown
Applications
n LED Driver
n Constant Current Source
Typical Application Circuit
Connection Diagrams
20178905
6-Lead TSOT
NS Package Number MK06A
© 2006 National Semiconductor Corporation DS201789
20178901
20178960
Pin 1 Indentification
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