LM337L 3-Terminal Adjustable Regulator
May 1998
LM337L
3-Terminal Adjustable Regulator
General Description
The LM337L is an adjustable 3-terminal negative voltage
regulator capable of supplying 100 mA over a 1.2V to 37V
output range. It is exceptionally easy to use and requires
only two external resistors to set the output voltage. Further-
more, both line and load regulation are better than standard
fixed regulators. Also, the LM337L is packaged in a standard
TO-92 transistor package which is easy to use.
In addition to higher performance than fixed regulators, the
LM337L offers full overload protection. Included on the chip
are current limit, thermal overload protection and safe area
protection. All overload protection circuitry remains fully func-
tional even if the adjustment terminal is disconnected.
Normally, only a single 1 µF solid tantalum output capacitor
is needed unless the device is situated more than 6 inches
from the input filter capacitors, in which case an input bypass
is needed. A larger output capacitor can be added to improve
transient response. The adjustment terminal can be by-
passed to achieve very high ripple rejection ratios which are
difficult to achieve with standard 3-terminal regulators.
Besides replacing fixed regulators, the LM337L is useful in a
wide variety of other applications. Since the regulator is
“floating” and sees only the input-to-output differential volt-
age, supplies of several hundred volts can be regulated as
long as the maximum input-to-output differential is not ex-
ceeded.
Also, it makes an especially simple adjustable switching
regulator, a programmable output regulator, or by connecting
a fixed resistor between the adjustment and output, the
LM337L can be used as a precision current regulator. Sup-
plies with electronic shutdown can be achieved by clamping
the adjustment terminal to ground which programs the out-
put to 1.2V where most loads draw little current.
The LM337L is available in a standard TO-92 transistor
package and a SO-8 surface mount package. The LM337L is
rated for operation over a −25˚C to +125˚C range.
For applications requiring greater output current in excess of
0.5A and 1.5A, see LM137 series data sheets. For the posi-
tive complement, see series LM117 and LM317L data
sheets.
Features
n
n
n
n
n
n
n
n
n
Adjustable output down to 1.2V
Guaranteed 100 mA output current
Line regulation typically 0.01%/V
Load regulation typically 0.1%
Current limit constant with temperature
Eliminates the need to stock many voltages
Standard 3-lead transistor package
80 dB ripple rejection
Output is short circuit protected
Connection Diagram
DS009134-1
Bottom View
Top View
Order Number LM337LM or LM337LZ
See NS Package Number M08A or Z03A
DS009134-2
© 1999 National Semiconductor Corporation
DS009134
www.national.com
NSC [ NATIONAL SEMICONDUCTOR ]
