LM2991 - Negative Low Dropout Adjustable Regulator

Datasheet	Packaging	Samples & Pricing	Reliability	Knowledge Base

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

General Description

The LM2991 is a low dropout adjustable negative regulator with a output voltage range between -3V to -24V. More...

Applications

•	Post switcher regulator
•	Local, on-card, regulation
•	Battery operated equipment

Typical Application

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Parameters Values

Output Current 1000 mA

Output Min -24 Volt

Input Min Voltage -26 Volt

Input Max Voltage 0.3 Volt

Dropout Voltage 0.6 Volt

Adjustable Output Yes

Quiescent Current 0.7 mA

On/Off Pin Yes

Error Flag No

RegType LDO

Temperature Min -40 deg C

Temperature Max 125 deg C

Output Max -3 Volt

Output Voltage Undefined Volt

Typical Performance

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Connection Diagram

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Datasheet

RoHS Compliance Information	Size in Kbytes	Date
LM2991 Negative Low Dropout Adjustable Regulator	346 Kbytes	14-Sep-00	Download
LM2991 Negative Low Dropout Adjustable Regulator (Japanese)	168 Kbytes
LM2991QML Negative Low Dropout Adjustable Regulator	682 Kbytes	10-Mar-06	Download

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Package Availability, Models, Samples & Pricing

Part Number

Package

Factory Lead Time

Models

Samples &
Electronic
Orders

Budgetary Pricing

Std
Pack
Size

Package
Marking
Format

Type

Pins

Spec.

MSL
Rating

Peak
Reflow

RoHS
Report

CAD
Symbols

Weeks

Qty

$US each

LM2991T

TO-220

NOPB
STD

1
1

NA
NA

RoHS

N/A

Full production

N/A

1K+

$1.35

rail
of
45

NSUZXYTTE#
LM2991T
P+

6 weeks

500

LM2991S

TO-263

NOPB
STD

3
3

245
235

RoHS

N/A

Full production

N/A

1K+

$1.35

rail
of
45

NSUZXYTTE#
LM2991S
P+

6 weeks

1000

LM2991SX

TO-263

NOPB
STD

3
3

245
235

RoHS

N/A

Full production

N/A

1K+

$1.35

reel
of
500

NSUZXYTTE#
LM2991S
P+

6 weeks

1000

LM2991 MD8

Unpackaged Die

Lifetime buy

N/A

CALL

tray
of
N/A

6 weeks

7500

5962-9650501QXA
(LM2991WG-QML)

CERPACK

RoHS

N/A

Full production

N/A

50+

$72.00

tray
of
42

NSZSSXXYYA
LM2991WG-
QML Q 5962-
9650501QXA

10 weeks

100

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

General 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 (V_OUT - V_IN < 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.

Reliability Metrics

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

[Information as of 8-Nov-2009]