Features 300 kHz fixed-frequency switching Switching synchronization with an external signal up to 400 kHz Optional pulse-skipping mode Adjustable secondary feedback Input undervoltage lockout Output undervoltage shutdown protection Output overvoltage shutdown protection Programmable soft-start (each controller) 5V, 50 mA linear regulator output Precision 2.5V reference output 28-pin TSSOP Description The LM2641 is a dual step-down power supply controller intended for application in notebook personal computers and other battery-powered equipment. Fixed-frequency synchronous drive of logic-level N-channel power MOSFETs is combined with an optional pulse-skipping mode to achieve ultra efficient power conversion over a 1000:1 load current range. The pulse-skipping mode can be disabled in favor of fixed-frequency operation regardless of the load current level. High DC gain and current-mode feedback control assure excellent line and load regulation and a wide loop bandwidth for fast response to dynamic loads. An internal oscillator fixes the switching frequency at 300 kHz. Optionally, switching can be synchronized to an external clock running as fast as 400 kHz. An optional soft-start feature limits current surges from the input power supply at start up and provides a simple means of start-up sequencing. Logic-level inputs allow the controllers to be turned ON and OFF separately. Key Specification 96% efficient 5.5 to 30V input range Dual outputs adjustable from 2.2 to 8V 0.5% typical load regulation error 0.002%/V typical line regulation error Applications Notebook and subnotebook computers Wireless data terminals Battery-powered instruments

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

Datasheets

Title		Size	Date	Other Language
	LM2641 Dual Adjustable Step-Down Switching Power Supply Controller	487 Kbytes	15-May-01	日本語

Part Number(s) (NSID)	Top View	Availability	Current Reported Stock	Budgetary Pricing	Pack Size
LM2641MTC-ADJ/NOPB LM2641MTC-ADJ RoHS Status	TSSOP	Full production Lead Time: 6 weeks	Distributor Region Qty DIGI-KEY Worldwide 0 MOUSER Worldwide 96	$3.57 each at 1K+ pcs	rail of 48
LM2641MTCX-ADJ/NOPB LM2641MTCX-ADJ RoHS Status	TSSOP	Full production Lead Time: 8 weeks	Distributor Region Qty DIGI-KEY Worldwide 0 TECHMOSA Asia Pacific 5000	$3.57 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 LM2641.

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 LM2641 is located at RoHS Status.

Part Number(s) (NSID)	Weight (milligrams)	Type	Pins	MSL Rating	Peak Reflow	RoHS Status	CAD Symbols	Models	Package Marking Format
LM2641MTC-ADJ/NOPB LM2641MTC-ADJ	111.551 112.001	TSSOP	28	3 3	260 235	Detail	Download	N/A	NSUZXYTTE# LM2641M TC-ADJ
LM2641MTCX-ADJ/NOPB LM2641MTCX-ADJ	111.551 112.001	TSSOP	28	3 3	260 235	Detail	Download	N/A	NSUZXYTTE# LM2641M TC-ADJ

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 LM2641.

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 LM2641 is located at RoHS Status.

CAD Symbols and Models Download LM2641 CAD Symbols

Models N/A

Reliability Metrics

Part Number	Process	EFR Reject	EFR Sample Size	PPM	LTA Rejects	LTA Device Hours	FITS	MTTF (Hours)
LM2641MTC-ADJ	LMDMOS	0	18295	0	0	2650000	2	751944735
LM2641MTCX-ADJ	LMDMOS	0	18295	0	0	2650000	2	751944735

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 LM2641.

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 LM2641 is located at RoHS Status.