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
OUT
−V
IN
≤ 3V).
Output voltage accuracy is guaranteed to ±5% over load,
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.
**Required for stability. Must be at least a 10 µF aluminum electrolytic ora1µFsolid tantalum to maintain stability. May be increased without bound to
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 10Ω over the same operating temperature range as the regulator.
June 1999
LM2990
Negative
Low
Dropout
Regulator
© 1999 National Semiconductor Corporation DS010801 www.national.com