Features ±1% feedback voltage accuracy over temperature Switching frequency from 50 kHz to 1 MHz Switching frequency synchronize range 250 kHz to 1 MHz Startup with a pre-biased output load Power stage input voltage from 1V to 14V Control stage input voltage from 3V to 6V Output voltage adjustable down to 0.6V Power Good flag and shutdown Output overvoltage and undervoltage detection Low-side adjustable current sensing Adjustable soft-start Tracking and sequencing with shutdown and soft start pins TSSOP-14 package Description The LM2747 is a high-speed synchronous buck regulator controller with a feedback voltage accuracy of ±1%. It can provide simple down conversion to output voltages as low as 0.6V. Though the control section of the IC is rated for 3 to 6V, the driver section is designed to accept input supply rails as high as 14V. The use of adaptive non-overlapping MOSFET gate drivers helps avoid potential shoot-through problems while maintaining high efficiency. The IC is designed for the more cost-effective option of driving only N-channel MOSFETs in both the high-side and low-side positions. It senses the low-side switch voltage drop for providing a simple, adjustable current limit. The LM2747 features a fixed-frequency voltage-mode PWM control architecture which is adjustable from 50 kHz to 1 MHz with one external resistor. In addition, the LM2747 also allows the switching frequency to be synchronized to an external clock signal over the range of 250 kHz to 1 MHz. This wide range of switching frequency gives the power supply designer the flexibility to make better tradeoffs between component size, cost and efficiency. Features include the ability to startup with a pre-biased load on the output, soft-start, input undervoltage lockout (UVLO) and Power Good (based on both undervoltage and overvoltage detection). In addition, the shutdown pin of the IC can be used for providing startup delay, and the soft-start pin can be used for implementing precise tracking, for the purpose of sequencing with respect to an external rail. Applications Down Conversion from 3.3V Cable Modem, DSL and ADSL Laser Jet and Ink Jet Printers Low Voltage Power Modules DSP, ASIC, Core and I/O

Also Recommended LM2743▲ Synchronous Buck Controller With Tracking And Soft-Start LM2745▲ +/- 1.5% Accuracy LM3743▲ Low-Voltage Synchronous Buck Controller In MSOP-10

Typical Application click for larger image	Block Diagram click for larger image
Typical Performance click for larger image

Parameters / Values	LM2747	LM2743	LM2745	LM3743
Output Current	20000 mA	20000 mA	20000 mA	10000 mA
Input Min Voltage	1 Volt	1 Volt	1 Volt	3 Volt
Input Max Voltage	17 Volt	16 Volt	17 Volt	5.5 Volt
Feedback Voltage	0.6 Volt	0.6 Volt	0.6 Volt	0.8 Volt
Feedback Tolerance	1 %		1.5 %	1.75 %
Frequency Min	50 kHz	50 kHz	50 kHz	300 kHz
Frequency Max	1000 kHz	2000 kHz	1000 kHz	1000 kHz
Efficiency (peak)	85 %	85 %	85 %	95 %
Output Range	0.6V to 13.5V	0.6V to 13.5V	0.6V to 13.5V	0.8V to 4.6V
Adj Switch Frequency	Yes	Yes	Yes	No
Adjustable Output	Yes	Yes	Yes	Yes
On/Off Pin	Yes	Yes	Yes	Yes
PowerGood / Error Flag	Yes	Yes	Yes	No
SoftStart	Yes	Yes	Yes	Yes
Sync Pin	Yes	No	Yes	No
Inverting	No	No	No	No
Flyback	No	No	No	No
Lossless Current Sense	Yes	Yes	Yes	Yes
RegType	Switching Controller	Switching Controller	Switching Controller	Switching Regulator
Temperature Min	-40 deg C	-40 deg C	-40 deg C	-40 deg C
Temperature Max	125 deg C	125 deg C	125 deg C	125 deg C
Channels	1 Channels	1 Channels	1 Channels	1 Channels
Special Features	Pre-bias startup; 40ns min on-time	2.7V UVLO; Tri-State output during SD; Tracking; Precision SD threshold	Pre-bias startup; 40ns min on-time	Pre-bias start-up; Hiccup mode; External programmable soft-start and tracking
Topology	Buck	Buck	Buck	Buck
PWM Mode	Voltage	Voltage	Voltage	Voltage
Step-Down	Yes	Yes	Yes	Yes
Step-Up	No	No	No	No
Output Power	Undefined Watt	Undefined Watt	Undefined Watt	Undefined Watt
Output Max	13.5 Volt	13.5 Volt	13.5 Volt	4.6 Volt
Output Min	0.6 Volt	0.6 Volt	0.6 Volt	0.8 Volt
PowerWise	Yes	Yes	Yes	Yes

Datasheets

Title		Size	Date	Other Language
	LM2747 Synchronous Buck Controller with Pre-bias Startup, and Optional Clock Synchronization	529 Kbytes	17-Jan-12	日本語

Application Notes

Title		Size	Date	Other Language
	AN-1603: Application Note 1603 LM274X Reference Designs	431 Kbytes	6-Dec-07	中文
	AN-1449: Application Note 1449 LM2747 Evaluation Board	594 Kbytes	11-Apr-06
	AN-1641: Application Note 1641 LM2747-19A Evaluation Board	2571 Kbytes	17-May-07
	AN-1437: Application Note 1437 Current Limit Foldback Improves Short Circuit Protection in LM2743/44 Family	470 Kbytes	25-May-06	中文

Other Technical Documents

Title		Type	Date
	Synchronous Rectification in High-Performance Power Converter Design	Power Designer	2007-03-21
	Optimizing Power Controller Designs through Effective Utilization of Performance Features (Adj Frequency & Sync, Ext Ref, Tracking, & Precision Enable)	Power Designer	2008-04-24

Part Number(s) (NSID)	Top View	Availability	Current Reported Stock	Budgetary Pricing	Pack Size
LM2747MTC/NOPB LM2747MTC RoHS Status	TSSOP	Full production Lead Time: 6 weeks	Distributor Region Qty ARROW Worldwide 221 DIGI-KEY Worldwide 102 MOUSER Worldwide 282 RS COMPONENTS Worldwide 13 TAYLOR Americas 221	$1.45 each at 1K+ pcs	rail of 94
LM2747MTCX/NOPB LM2747MTCX RoHS Status	TSSOP	Full production Lead Time: 6 weeks	Distributor Region Qty CEAC Asia Pacific 20000 DIGI-KEY Worldwide 0	$1.45 each at 1K+ pcs	reel of 2500

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 LM2747.

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 LM2747 is located at RoHS Status.

Part Number(s) (NSID)	Description	Availability	Current Reported Stock	Budgetary Pricing	Pack Size
LM2747-19AEVAL	LM2747 Synchronous Buck Controller with Pre-bias Startup, and Optional Clock Synchronization	Full production	Distributor Region Qty DIGI-KEY Worldwide 0	$65.30 each	1
Features: ± feedback voltage accuracy over temperature Switching frequency from 50 kHz to 1 MHz Switching frequency synchronize range 250 kHz to 1 MHz Startup with a pre-biased output load Power stage input voltage from 1V to 14V Control stage input voltage from 3V to 6V Output voltage adjustable down to 0.6V Power Good flag and shutdown Output overvoltage and undervoltage detection Low-side adjustable current sensing Adjustable soft-start Tracking and sequencing with shutdown and soft-start pins TSSOP-14 package Applications: Down Conversion from 3.3V Cable Modem, DSL and ADSL Laser Jet and Ink Jet Printers Low Voltage Power Modules DSP, ASIC, Core and I/O Contents: A LM2747-19A Fully Assembled Evaluation Board A LM2747 Datasheet A LM2747 Evaluation Board Appnote

Part Number(s) (NSID)	Description	Availability	Current Reported Stock	Budgetary Pricing	Pack Size
LM2747EVAL	Synchronous Buck Controller with Pre-bias Startup, and Optional Clock Synchronization	Full production	Distributor Region Qty DIGI-KEY Worldwide 0	$65.30 each	1
Description: LM2747 Synchronous Buck Controller with Pre-bias Start-up, and Optional Clock Synchronization Features: ±1% feedback voltage accuracy over temperature Switching frequency synchronize range 250 kHz to 1MHz Startup with a pre-biased output load Power stage input voltage from 1V to 14V Control stage input voltage from 3V to 6V Output voltage adjustable down to 0.6V Power Good flag and shutdonwn Output overvoltage and undervoltage detection Low-side adjustable current sensing Adjustable soft-start Tracking and sequencing with shutdown and soft start pins TSSOP-14 package Applications: Down Conversion from 3.3V Cable Modem, DSL, and ADSL Laser Jet and Ink Jet Printers Low Voltage Power Modules DSP, ASIC, Core and I/O Contents: A fully assembled LM2747 evaluation board LM2747 datasheet LM2747 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
LM2747MTC/NOPB LM2747MTC	53.783 54.004	TSSOP	14	1 1	260 260	Detail	Download	N/A	NSUZXYTT 2747 MTC
LM2747MTCX/NOPB LM2747MTCX	53.783 54.004	TSSOP	14	1 1	260 260	Detail	Download	N/A	NSUZXYTT 2747 MTC

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 LM2747.

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 LM2747 is located at RoHS Status.

Design Tools

Title	Size	Date
Article - Exploit Controller Features to Optimize Power Designs

CAD Symbols and Models Download LM2747 CAD Symbols

Models N/A

Reliability Metrics

Part Number	Process	EFR Reject	EFR Sample Size	PPM	LTA Rejects	LTA Device Hours	FITS	MTTF (Hours)
LM2747MTC	ABCD150	0	42680	0	0	6394000	1	1814314958
LM2747MTCX	ABCD150	0	42680	0	0	6394000	1	1814314958

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 LM2747.

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 LM2747 is located at RoHS Status.