LM2990

Negative Low Dropout Regulator

General Description

The LM2990 is a three-terminal, low dropout, 1 ampere

negative voltage regulator available with fixed output volt-

ages of −5, −5.2, −12, and −15V.

The LM2990 uses new circuit design techniques to provide

low dropout and low quiescent current. The dropout voltage

at 1A load current is typically 0.6V and a guaranteed

worst-case maximum of 1V over the entire operating tem-

perature range. The quiescent current is typically 1 mA with

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

and temperature extremes.

The LM2990 is short-circuit proof, and thermal shutdown in-

cludes hysteresis to enhance the reliability of the device

when overloaded for an extended period of time. The

LM2990 is available in a 3-lead TO-220 package and is rated

for operation over the automotive temperature range of

−40˚C to +125˚C.

Features

n 5% output accuracy over entire operating range

n Output current in excess of 1A

n Dropout voltage typically 0.6V at 1A load

n Low quiescent current

n Internal short circuit current limit

n Internal thermal shutdown with hysteresis

n Functional complement to the LM2940 series

Applications

n Post switcher regulator

n Local, on-card, regulation

n Battery operated equipment

Typical Application

Ordering Information and Connection Diagrams

Temperature

Range

Output Voltage

Package

-5.0

-5.2

-12

-15

−40˚C to

+125˚C

LM2990T-5.0

LM2990T-5.2

LM2990T-12

LM2990T-15

TO-220

LM2990S-5.0

LM2990S-12

LM2990S-15

TO-263

−55˚C to

+125˚C

LM2990J-5.0-QML

5962-9571101QEA

LM2990J-12-QML

5962-9571001QEA

LM2990J-15-QML

5962-9570901QEA

J16A

LM2990WG5.0-QML

5962-9571101QXA

WG16A

DS010801-1

*Required if the regulator is located further than 6 inches from the power supply filter capacitors. A 1 µF solid tantalum or a 10 µF aluminum electrolytic

capacitor is recommended.

maintain regulation during transients. Locate the capacitor as close as possible to the regulator. The equivalent series resistance (ESR) is critical, and

should be less than 10

Ω over the same operating temperature range as the regulator.

June 1999

© 1999 National Semiconductor Corporation

DS010801

www.national.com