Features Input voltage range from 5.5V to 28V Synchronous dual-channel Interleaved switching Forced-PWM or Pulse-skip modes Lossless bottom-side FET current sensing Adaptive duty cycle clamping High current N-channel FET drivers Low shutdown supply currents Reference voltage accurate to within ±1.5% Output voltage adjustable down to 0.6V Power Good flag and Chip Enable Under-voltage lockout Over-voltage/Under-voltage protection Soft-start and Soft-shutdown Switching frequency adjustable 200kHz-500kHz Description The LM2647 is an adjustable 200-500kHz dual channel voltage-mode controlled high-speed synchronous buck regulator controller ideally suited for battery powered applications such as laptop and notebook computers. The LM2647 requires only N-channel FETs for both the upper and lower positions of each synchronous stage. It features line feedforward to improve the response to input transients. At very light loads, the user can choose between the high-efficiency Pulse-skip mode or the constant frequency Forced-PWM mode. Lossless current limiting without the use of external sense resistors is made possible by sensing the voltage drop across the bottom FET. A unique adaptive duty cycle clamping technique is incorporated to significantly reduce peak currents under abnormal load conditions. The two independently programmable outputs switch 180° out of phase (interleaved switching) to reduce the input capacitor and filter requirements. The input voltage range is 5.5V to 28V while the output voltages are adjustable down to 0.6V. Standard supervisory and control features include Soft-start, Power Good, output Under-voltage and Over-voltage protection, Under-voltage Lockout, Soft-shutdown and Enable. Applications Notebook Chipset Power Supplies Low Output Voltage High-Efficiency Buck Regulators

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

Parameters Values Channels 2 Channels Topology Buck Output Current 20000 mA Input Min Voltage 5.5 Volt Input Max Voltage 28 Volt Output Range 0.6V to 5V Frequency Min 200 kHz Frequency Max 500 kHz Feedback Voltage 0.6 Volt Feedback Tolerance 1.5 % Adj Switch Frequency Yes Adjustable Output Yes Synchronous Rectification Yes On/Off Pin Yes PowerGood / Error Flag Yes SoftStart Yes Sync Pin No Inverting No Flyback No Lossless Current Sense Yes RegType Switching Controller Temperature Min -5 deg C Temperature Max 125 deg C Special Features PWM/SKIP and FPWM modes; Soft shutdown; Line feedforward; 180deg out-of-phase PWM Mode Voltage with Vin Feedforward Step-Down Yes Step-Up No Output Max 5 Volt Output Min 0.6 Volt

Datasheets

Title		Size	Date	Other Language
	LM2647 Dual Synchronous Buck Regulator Controller	1726 Kbytes	29-Jun-05

Part Number(s) (NSID)	Top View	Availability	Current Reported Stock	Budgetary Pricing	Pack Size
LM2647LQ/NOPB LM2647LQ RoHS Status	LLP	Full production Lead Time: 6 weeks	Distributor Region Qty DIGI-KEY Worldwide 819 MOUSER Worldwide 1000	$1.90 each at 1K+ pcs	reel of 1000
LM2647LQX/NOPB LM2647LQX RoHS Status	LLP	Full production Lead Time: 6 weeks	Distributor Region Qty DIGI-KEY Worldwide 0	$1.90 each at 1K+ pcs	reel of 4500
LM2647MTC/NOPB LM2647MTC RoHS Status	TSSOP	Full production Lead Time: 6 weeks	Distributor Region Qty AVNET-EM Worldwide 192 DIGI-KEY Worldwide 386 MOUSER Worldwide 42 RS COMPONENTS Worldwide 48	$1.90 each at 1K+ pcs	rail of 48
LM2647MTCX/NOPB LM2647MTCX RoHS Status	TSSOP	Full production Lead Time: 8 weeks	Distributor Region Qty DIGI-KEY Worldwide 0 TECHMOSA Asia Pacific 2500	$1.90 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 LM2647.

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 LM2647 is located at RoHS Status.

Part Number(s) (NSID)	Description	Availability	Current Reported Stock	Budgetary Pricing	Pack Size
LM2647EVAL	Dual Synchronous Buck Regulator Controller	Full production	Distributor Region Qty DIGI-KEY Worldwide 0 TAYLOR Americas 2	$153.00 each	1
Description: LM2647 Dual Synchronous Buck Regulator Controller Features: Input voltage range from 5.5V to 28V Synchronous dual-channel interleaved switching Forced-PWM or Pulse-skip modes Lossless bottom-side FET current sensing Adaptive duty cycle clamping High current N-channel FET drivers Low shutdown supply currents Reference voltage accurate to within ?1.5% Output voltage adjustable down to 0.6V Power Good flag and Chip Enable Under-voltage lockout Over-voltage/Under-voltage protection Soft-start and Soft-shutdown Switching frequency adjustable 200kHz-500kHz Applications: Notebook chipset power supplies Low output voltage high-efficiency buck regulators Contents: A fully assembled LM2647 evaluation board LM2647 datasheet (eval board appnote included in datasheet)

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
LM2647LQ/NOPB LM2647LQ	59.866 60.094	LLP	28	1 1	260 260	Detail	Download	N/A	NS UZXYTTE# LM2647
LM2647LQX/NOPB LM2647LQX	59.866 60.094	LLP	28	1 1	260 260	Detail	Download	N/A	NS UZXYTTE# LM2647
LM2647MTC/NOPB LM2647MTC	111.551 112.001	TSSOP	28	3 3	260 235	Detail	Download	N/A	NSUZXYTTE# LM2647 MTC
LM2647MTCX/NOPB LM2647MTCX	111.551 112.001	TSSOP	28	3 3	260 235	Detail	Download	N/A	NSUZXYTTE# LM2647 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 LM2647.

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 LM2647 is located at RoHS Status.

CAD Symbols and Models Download LM2647 CAD Symbols

Models N/A

Reliability Metrics

Part Number	Process	EFR Reject	EFR Sample Size	PPM	LTA Rejects	LTA Device Hours	FITS	MTTF (Hours)
LM2647LQ	ABCD150	0	42680	0	0	6394000	1	1814314958
LM2647LQX	ABCD150	0	42680	0	0	6394000	1	1814314958
LM2647MTC	ABCD150	0	42680	0	0	6394000	1	1814314958
LM2647MTCX	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 LM2647.

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 LM2647 is located at RoHS Status.