1.6-MHz 1-A Constant Current Buck LED Driver - Texas Instruments
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LM3405
SNVS429C – OCTOBER 2006 – REVISED DECEMBER 2016
LM3405 1.
6-MHz, 1-A Constant Current Buck Regulator For Powering LEDS
1 Features
•1 VIN Operating Range of 3 V to 15 V • Drives up to 5 High-Brightness LEDs in Series at
1A • Thin SOT-6 Package • 1.
6-MHz Switching Frequency • EN/DIM Input for Enabling and PWM Dimming of
LEDs • 300-mΩ NMOS Switch • 40-nA Shutdown Current at VIN = 5 V • Internally Compensated Current-mode Control • Cycle-by-Cycle Current Limit • Input Voltage UVLO • Overcurrent Protection • Thermal Shutdown
2 Applications
• LED Drivers • Constant Current Sources • Industrial Lighting • LED Flashlights
Typical Application Circuit
D2
3 Description
The LM3405 is a 1-A constant current buck LED driver designed to provide a simple, high efficiency solution for driving high power LEDs.
With a 0.
205-V reference voltage feedback control to minimize power dissipation, an external resistor sets the current as required for driving various types of LEDs.
Switching frequency is internally set to 1.
6 MHz, allowing small surface mount inductors and capacitors to be used.
The LM3405 uses current-mode control and internal compensation offering ease of use and predictable, high performance regulation over a wide range of operating conditions.
With a maximum input voltage of 15 V, the device can drive up to 3 High-Brightness LEDs in series at 1-A forward current, with the single LED forward voltage of approximately 3.
7 V.
Additional features include user accessible EN/DIM pin for enabling and PWM dimming of LEDs, thermal shutdown, cycle-by-cycle current limit and overcurrent protection.
Device Information(1)
PART NUMBER
PACKAGE
BODY SIZE (NOM)
LM3405
SOT (6)
2.
90 mm × 1.
60 mm
(1) For all available packages, see the orderable addendum at the end of the data sheet.
Efficiency vs LED Current (VIN = 5 V)
VIN C1
ON OFF
VIN BOOST
C3
LM3405 EN/DIM
SW D1
GND
FB
L1 VO...
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