Features • VIN 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 VIN = 5V • Internally compensated current-mode control • Cycle-by-cycle current limit • Input voltage UVLO • Over-current protection • Thermal shutdown Description The LM3405A is a 1A constant current buck LED driver 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 LM3405A utilizes 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 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. Applications • LED Driver • Constant Current Source • Industrial Lighting • LED Flashlights • LED Lightbulbs

LM3405A   3.00 <= V in Lower  V   <= V in Upper  V   <= 22.00 Ambient Temperature  °C <= 100 What are WEBENCH® tools? Series zener diode from Vin MY BRIEFCASE                                       Click any "Briefcase" icon to add an item

Typical Application click for larger image Series zener diode from Vin	Block Diagram click for larger image temporary
Typical Performance click for larger image Efficiency vs. LED Current for Vin = 12V, 1 and 2 LEDs

Datasheet

Title		Size	Date	Other Language
	LM3405A 1.6MHz, 1A Constant Current Buck LED Driver with Internal Compensation in Tiny SOT23 and eMSOP Package	516 Kbytes	23-Oct-08

Featured Application Notes

Title		Size	Date	Other Language
	AN-1685: Application Note 1685 LM3405A Demo Board	907 Kbytes	19-Oct-07	中文
	AN-1899: Application Note 1899 LM3405A eMSOP Evaluation Board	442 Kbytes	6-Jul-09	中文

More Application Notes

Title		Size	Date	Other Language
	AN-1644: Application Note 1644 Powering and Dimming High-Brightness LEDs with the LM3405 Constant-Current Buck Regulator	174 Kbytes	17-Jan-08
	AN-1590: Application Note 1590 LM3405 Demo Board	475 Kbytes	19-Mar-07

Design Tools

Reference Design

RD-148 - LM3405A Reference Design for MR16 LED Bulb, 600mA

Reliability Metrics

Part Number	Process	EFR Reject	EFR Sample Size	PPM	LTA Rejects	LTA Device Hours	FITS	MTTF (Hours)
LM3405AXMK	PVIP050	0	9960	0	0	855000	5	242608584
LM3405AXMKE	PVIP050	0	9960	0	0	855000	5	242608584
LM3405AXMKX	PVIP050	0	9960	0	0	855000	5	242608584
LM3405AXMY	PVIP050	0	9960	0	0	855000	5	242608584
LM3405AXMYX	PVIP050	0	9960	0	0	855000	5	242608584

Note: The Early Failure Rates (EFR) were calculated as point estimate PPM based on rejects and sample size for EFR. The Long Term Failure Rates were calculated at 60% confidence using the Arrhenius equation at 0.7eV activation energy and derating the assumed stress temperature of 150°C to an application temperature of 55°C.

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