Features Output voltage adjustable from −3V to −24V, typically −2V to −25V Output current in excess of 1A Dropout voltage typically 0.6V at 1A load Low quiescent current Internal short circuit current limit Internal thermal shutdown with hysteresis TTL, CMOS compatible ^ON/OFF switch Functional complement to the LM2941 series Description The LM2991 is a low dropout adjustable negative regulator with a output voltage range between −3V to −24V. The LM2991 provides up to 1A of load current and features a ^On /Off pin for remote shutdown capability. The LM2991 uses new circuit design techniques to provide a low dropout voltage, low quiescent current and low temperature coefficient precision reference. The dropout voltage at 1A load current is typically 0.6V and a guaranteed worst-case maximum of 1V over the entire operating temperature range. The quiescent current is typically 1 mA with a 1A load current and an input-output voltage differential greater than 3V. A unique circuit design of the internal bias supply limits the quiescent current to only 9 mA (typical) when the regulator is in the dropout mode (VOUT − VIN ≤ 3V). The LM2991 is short-circuit proof, and thermal shutdown includes hysteresis to enhance the reliability of the device when inadvertently overloaded for extended periods. The LM2991 is available in 5-lead TO-220 and TO-263 packages and is rated for operation over the automotive temperature range of −40°C to +125°C. Mil-Aero versions are also available. Applications Post switcher regulator Local, on-card, regulation Battery operated equipment

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

Datasheets

Title		Size	Date	Other Language
	LM2991 Negative Low Dropout Adjustable Regulator	389 Kbytes	4-May-11	日本語

Other Technical Documents

Title		Type	Date
	Linear and Switching Voltage Regulator Fundamental Part 1	App Note	2007-03-21

Part Number(s) (NSID)	Top View	Availability	Current Reported Stock	Budgetary Pricing	Pack Size
LM2991S/NOPB LM2991S RoHS Status	TO-263	Full production Lead Time: 8 weeks	Distributor Region Qty ARROW Worldwide 124 AVNET-EM Worldwide 706 DIGI-KEY Worldwide 1250 FARNELL Europe and Asia 1917 MOUSER Worldwide 624 NEWARK Americas 1239 RS COMPONENTS Worldwide 22 TAYLOR Americas 7043	$1.35 each at 1K+ pcs	rail of 45
LM2991SX/NOPB LM2991SX RoHS Status	TO-263	Full production Lead Time: 6 weeks	Distributor Region Qty ARROW Worldwide 953 AVNET-EM Worldwide 2000 DIGI-KEY Worldwide 1321 FARNELL Europe and Asia 68 MOUSER Worldwide 185 NEWARK Americas 68 TAYLOR Americas 2787	$1.35 each at 1K+ pcs	reel of 500
LM2991T/NOPB LM2991T RoHS Status		Full production Lead Time: 6 weeks	Distributor Region Qty ARROW Worldwide 905 AVNET-EM Worldwide 1157 DIGI-KEY Worldwide 523 FARNELL Europe and Asia 1135 MOUSER Worldwide 444 NEWARK Americas 158 RS COMPONENTS Worldwide 89 TAYLOR Americas 1503	$1.35 each at 1K+ pcs	rail of 45

Obsolete Versions

Obsolete Part	Alternate Part or Supplier	Source	Last Time Buy Date
LM2991J-QML	NONE	NATIONAL SEMICONDUCTOR	03 Dec 2008
LM2991J-QMLV	NONE	NATIONAL SEMICONDUCTOR	03 Dec 2008
LM2991T MWC	NONE	NONE	08 Sep 1999

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 LM2991.

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 LM2991 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
LM2991S/NOPB LM2991S	1448.647 1449.868	TO-263	5	3 3	245 235	Detail	N/A	N/A	NSUZXYTTE# LM2991S P+
LM2991SX/NOPB LM2991SX	1448.647 1449.868	TO-263	5	3 3	245 235	Detail	N/A	N/A	NSUZXYTTE# LM2991S P+
LM2991T/NOPB LM2991T	1907.045 1909.935	TO-220	5	1 1	NA NA	Detail	N/A	N/A	NSUZXYTTE# LM2991T P+

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 LM2991.

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 LM2991 is located at RoHS Status.

CAD Symbols and Models N/A

Models N/A

Reliability Metrics

Part Number	Process	EFR Reject	EFR Sample Size	PPM	LTA Rejects	LTA Device Hours	FITS	MTTF (Hours)
LM2991S	SLM	0	44046	0	0	3532500	1	1002356520
LM2991SX	SLM	0	44046	0	0	3532500	1	1002356520
LM2991T	SLM	0	44046	0	0	3532500	1	1002356520

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 LM2991.

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 LM2991 is located at RoHS Status.

Obsolete Versions

Obsolete Part	Alternate Part or Supplier	Source	Last Time Buy Date
LM2991J-QML	NONE	NATIONAL SEMICONDUCTOR	03 Dec 2008
LM2991J-QMLV	NONE	NATIONAL SEMICONDUCTOR	03 Dec 2008
LM2991T MWC	NONE	NONE	08 Sep 1999