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

MY BRIEFCASE                                       Click any "Briefcase" icon to add an item

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

Datasheet

Title		Size	Date	Other Language
	LM2991 Negative Low Dropout Adjustable Regulator	346 Kbytes	14-Sep-00	日本語

Featured Application Notes

Title		Size	Date	Other Language
	AN-1378: Application Note 1378 Method For Calculating Output Voltage Tolerances in Adjustable Regulators	647 Kbytes	15-Jul-05	中文

More Application Notes

Title		Size	Date	Other Language
	AN-1378: Application Note 1378 Method For Calculating Output Voltage Tolerances in Adjustable Regulators	647 Kbytes	15-Jul-05	中文

Part Number(s) (NSID)	Top View	Availability	Current Reported Stock	Budgetary Pricing	Standard Pack Size
LM2991T/NOPB LM2991T RoHS		Full production Lead Time: 8 weeks	Distributor Region Qty ARROW Worldwide 354 DIGIKEY Worldwide 1128 FARNELL Europe and Asia 1632 FUTURE Worldwide 725 KEIKONG Asia Pacific 1080 RS COMPONENTS Worldwide 89 TAYLOR Americas 42	$1.35 each at 1K+ pcs	rail of 45
LM2991S/NOPB LM2991S RoHS	TO-263	Full production Lead Time: 6 weeks	Distributor Region Qty ARROW Worldwide 1561 DIGIKEY Worldwide 0 FARNELL Europe and Asia 1127 FUTURE Worldwide 225 NEWARK Americas 69 RS COMPONENTS Worldwide 22 TAYLOR Americas 21	$1.35 each at 1K+ pcs	rail of 45
LM2991SX/NOPB LM2991SX RoHS	TO-263	Full production Lead Time: 6 weeks	Distributor Region Qty ARROW Worldwide 121 DIGIKEY Worldwide 0 NEWARK Americas 592	$1.35 each at 1K+ pcs	reel of 500
LM2991 MD8 RoHS		Lifetime buy Lead Time: 6 weeks	Contact your distributor	CALL	tray of N/A
5962-9650501QXA (LM2991WG-QML)		Full production Lead Time: 10 weeks	Contact your distributor	$72.00 each at 50+ pcs	tray of 42

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

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.

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