Features • Input voltage from 3.0V to 5.5V • Output voltage adjustable down to 0.8V • Reference accuracy: ±1.75%, over full temperature and input voltage range • High-side and Low-side N-Channel MOSFETs • Switching frequency options of 1 MHz or 300 kHz • Comprehensive Fault Protection Features: •  High-side current limit •  Low-side current limit •  Output under-voltage protection • Hiccup mode protection eliminates thermal runaway during fault conditions • Externally programmable soft-start with tracking capability • Pre-bias start-up capability • MSOP-10 package Description The LM3743 is a DC-DC voltage mode PWM buck controller featuring synchronous rectification at 300 kHz or 1 MHz. It can deliver current as high as 20A and step down from an input voltage between 3V and 5.5V down to a minimum output voltage of 0.8V, with a ±1.75% internal reference accuracy. The LM3743 provides a set of comprehensive fault protection features such as high-side current limit, output under-voltage protection, and low-side current limit. When any of these fault protection features are engaged, it enters a hiccup protection mode which is suitable for high reliability systems such as rack mounted servers and telecom base station subsystems. The LM3743 also employs a proprietary monolithic glitch free pre-bias start-up method suited for FPGA and ASIC logic devices. An external programmable soft-start allows for tracking and timing flexibility. The driver features 1.6Ω of pull-up resistance and 1Ω of pull-down drive resistance for high power density and very efficient power processing. Applications • Rack-mount servers • Telecom base stations • Routers • Printers/Scanners • Multi-media set-top boxes • FPGAs, ASICs, and DSPs

Also Recommended LM1770▲ SOT23 Synchronous Buck Controller LM1771▲ Synchronous Buck Controller With Precision Enable LM2743▲ Synchronous Buck Controller With Vin Up To 16V MY BRIEFCASE                                       Click any "Briefcase" icon to add an item

Typical Application click for larger image	Block Diagram click for larger image
Typical Performance *click for larger image 300 kHz, Vout = 2.5V

Datasheets

Title		Size	Date	Other Language
	LM3743 High-Performance Synchronous Buck Controller with Comprehensive Fault Protection Features	590 Kbytes	7-Oct-08

Featured Application Notes

Title		Size	Date	Other Language
	AN-1669: Application Note 1669 LM3743 High Performance Controller with Comprehensive Fault Protection Features Designed for High Reliability Systems	118 Kbytes	19-Jun-07	日本語 中文
	AN-1450: Application Note 1450 LM3743 Evaluation Board	694 Kbytes	12-Sep-06	中文
	AN-1997: Application Note 1997 Error Amplifier Limitations in High Performance Regulator Applications	274 Kbytes	13-Nov-09

Part Number(s) (NSID)	Top View	Availability	Current Reported Stock	Budgetary Pricing	Standard Pack Size
LM3743MM-1000/NOPB LM3743MM-1000 RoHS Status	MINI SOIC	Full production Lead Time: 6 weeks	Distributor Region Qty DIGIKEY Worldwide 1927 FARNELL Europe and Asia 48	$1.10 each at 1K+ pcs	reel of 1000
LM3743MM-300/NOPB LM3743MM-300 RoHS Status	MINI SOIC	Full production Lead Time: 6 weeks	Distributor Region Qty DIGIKEY Worldwide 1731 FARNELL Europe and Asia 1012 FUTURE Worldwide 1100	$1.10 each at 1K+ pcs	reel of 1000
LM3743MMX-1000/NOPB LM3743MMX-1000 RoHS Status	MINI SOIC	Full production Lead Time: 6 weeks	Distributor Region Qty DIGIKEY Worldwide 0	$1.10 each at 1K+ pcs	reel of 3500
LM3743MMX-300/NOPB LM3743MMX-300 RoHS Status	MINI SOIC	Full production Lead Time: 6 weeks	Distributor Region Qty DIGIKEY Worldwide 0	$1.10 each at 1K+ pcs	reel of 3500

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

A RoHS compliance or an IPC 1752 report can be acquired at http://www.national.com/quality/green.

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

Part Number(s) (NSID)	Top View	Type	Pins	MSL Rating	Peak Reflow	RoHS Status	CAD Symbols	Models	Package Marking Format
LM3743MM-1000/NOPB LM3743MM-1000		MINI SOIC	10	1 1	260 260	Detail	Download	N/A	ZXTT SKNB
LM3743MM-300/NOPB LM3743MM-300		MINI SOIC	10	1 1	260 260	Detail	Download	N/A	ZXTT SKPB
LM3743MMX-1000/NOPB LM3743MMX-1000		MINI SOIC	10	1 1	260 260	Detail	Download	N/A	ZXTT SKNB
LM3743MMX-300/NOPB LM3743MMX-300		MINI SOIC	10	1 1	260 260	Detail	Download	N/A	ZXTT SKPB

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

A RoHS compliance or an IPC 1752 report can be acquired at http://www.national.com/quality/green.

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

Design Tools

Title	Size	Date
Article - Voltage Mode Compensation of Buck Regulators

CAD Symbols and Models Download LM3743 CAD Symbols

Models N/A

Reliability Metrics

Part Number	Process	EFR Reject	EFR Sample Size	PPM	LTA Rejects	LTA Device Hours	FITS	MTTF (Hours)
LM3743MM-1000	PVIP050	0	9960	0	0	855000	5	242608584
LM3743MM-300	PVIP050	0	9960	0	0	855000	5	242608584
LM3743MMX-1000	PVIP050	0	9960	0	0	855000	5	242608584
LM3743MMX-300	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.

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/packaging/leadfree.

A RoHS compliance or an IPC 1752 report can be acquired at http://www.national.com/quality/green.

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