Features VIN operating range of 3V to 15V Thin SOT23-6 package 1.6MHz switching frequency 300mΩ NMOS switch 40nA shutdown current at VIN = 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 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 frequency 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. Applications LED Driver Constant Current Source Industrial Lighting LED Flashlights

Also Recommended LM3405A▲ Extended Input Voltage Range Up To 22V redraw to make it compact

Typical Application click for larger image redraw to make it compact	Block Diagram click for larger image Simplified Internal Block Diagram, add IF and VOUT
Typical Performance click for larger image Efficiency vs. LED Current for Vin = 5V

Parameters / Values	LM3405	LM3405A
Topology	Buck	Buck
Input Min Voltage	3 Volt	3 Volt
Input Max Voltage	15 Volt	22 Volt
Output Range	0.2V to 13.5V	0.2V to 20V
Output Current	1000 mA	1000 mA
Efficiency (peak)	92 %	92 %
Output Min	0.2 Volt	0.2 Volt
Output Max	13.5 Volt	20 Volt
Adjustable Output	Yes	Yes
Dimming Method	PWM	PWM
Power Factor Correction	None	None
On/Off Pin	Yes	Yes
PowerGood / Error Flag	No	No
Switching Frequency	Undefined kHz	1600 kHz
Adj Switch Frequency	No	No
Sync Pin	No	No
Step-Down	Yes	Yes
RegType	Switching Regulator	Switching Regulator
Temperature Min	-40 deg C	-40 deg C
Temperature Max	125 deg C	125 deg C
Feedback Voltage	0.2 Volt	0.2 Volt
PowerWise	Yes	Yes

Datasheets

Title		Size	Date	Other Language
	LM3405 1.6MHz 1A Constant Current Buck Regulator for Powering LEDs	486 Kbytes	16-Feb-07	日本語

Application Notes

Title		Size	Date	Other Language
	AN-1982: Application Note 1982 Small, Wide Input Voltage Range LM2842 Keeps LEDs Cool	63 Kbytes	15-Jul-09
	AN-1590: Application Note 1590 LM3405 Hi Power PSOP-8 Evaluation Board	475 Kbytes	19-Mar-07
	AN-1644: Application Note 1644 Powering and Dimming High-Brightness LEDs with the LM3405 Constant-Current Buck Regulator	174 Kbytes	17-Jan-08
	AN-1685: Application Note 1685 LM3405A Evaluation Board	907 Kbytes	19-Oct-07	中文
	AN-1656: Application Note 1656 Design Challenges of Switching LED Drivers	203 Kbytes	18-Oct-07	日本語 中文

Part Number(s) (NSID)	Top View	Availability	Current Reported Stock	Budgetary Pricing	Pack Size
LM3405XMK/NOPB LM3405XMK RoHS Status	TSOT	Full production Lead Time: 6 weeks	Distributor Region Qty DIGI-KEY Worldwide 1454 FARNELL Europe and Asia 509 MOUSER Worldwide 1824 NEWARK Americas 509	$0.95 each at 1K+ pcs	reel of 1000
LM3405XMKX/NOPB LM3405XMKX RoHS Status	TSOT	Full production Lead Time: 6 weeks	Distributor Region Qty DIGI-KEY Worldwide 0	$0.95 each at 1K+ pcs	reel of 3000

All information pertaining to the RoHS Compliance Standard can be found at http://www.national.com/en/packaging/leadfree.html.

Moisture Sensitivity Level Data for LM3405.

A RoHS compliance or an IPC 1752 report can be acquired at http://www.national.com/en/packaging/greennopb.html.

National's certificate of product compliance for LM3405 is located at RoHS Status.

Part Number(s) (NSID)	Description	Availability	Current Reported Stock	Budgetary Pricing	Pack Size
LM3405XEVAL/NOPB	1.6MHz, 1A Constant Current Buck Regulator for Powering LEDs	Full production Lead Free (RoHS)	Distributor Region Qty DIGI-KEY Worldwide 0	$40.50 each	1
Features: VIN operating range of 3V to 15V Thin SOT23-6 package 1.6MHz switching frequency 300mΩ NMOS switch 40nA shutdown current at VIN = 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 Contents: A LM3405X Fully Assembled Evaluation Board A LM3405 Datasheet A LM3405 Evaluation Board Appnote

National Semiconductor follows the provisions of the Product Stewardship Guide for Customers (CSP-9-111C1) and Banned Substances and Materials of Interest Specification (CSP-9-111S2) for regulatory environmental compliance. Details may be found at: www.national.com/en/packaging/greennopb.html. Lead free products are RoHS compliant.

Lead Free product status is available through the search tool located here

Part Number(s) (NSID)	Weight (milligrams)	Type	Pins	MSL Rating	Peak Reflow	RoHS Status	CAD Symbols	Models	Package Marking Format
LM3405XMK/NOPB LM3405XMK	13.726 13.851	TSOT	6	1 1	260 260	Detail	Download	N/A	SPNB XTT
LM3405XMKX/NOPB LM3405XMKX	13.726 13.851	TSOT	6	1 1	260 260	Detail	Download	N/A	SPNB XTT

All information pertaining to the RoHS Compliance Standard can be found at http://www.national.com/en/packaging/leadfree.html.

Moisture Sensitivity Level Data for LM3405.

A RoHS compliance or an IPC 1752 report can be acquired at http://www.national.com/en/packaging/greennopb.html.

National's certificate of product compliance for LM3405 is located at RoHS Status.

Design Tools

Title	Size	Date
Article - Contact us for questions on this product

CAD Symbols and Models Download LM3405 CAD Symbols

Models N/A

Reliability Metrics

Part Number	Process	EFR Reject	EFR Sample Size	PPM	LTA Rejects	LTA Device Hours	FITS	MTTF (Hours)
LM3405XMK	PVIP050	0	14280	0	0	1755000	3	497986041
LM3405XMKX	PVIP050	0	14280	0	0	1755000	3	497986041

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.

For more information on Reliability Metrics, please click here.

All information pertaining to the RoHS Compliance Standard can be found at http://www.national.com/en/packaging/leadfree.html.

Moisture Sensitivity Level Data for LM3405.

A RoHS compliance or an IPC 1752 report can be acquired at http://www.national.com/en/packaging/greennopb.html.

National's certificate of product compliance for LM3405 is located at RoHS Status.