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 F 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 -25C to +125C 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
Adjustable output down to 1.2V
n
Guaranteed 100 mA output current
n
Line regulation typically 0.01%/V
n
Load regulation typically 0.1%
n
Current limit constant with temperature
n
Eliminates the need to stock many voltages
n
Standard 3-lead transistor package
n
80 dB ripple rejection
n
Output is short circuit protected
Connection Diagram
DS009134-1
Bottom View
DS009134-2
Top View
Order Number LM337LM or LM337LZ
See NS Package Number M08A or Z03A
May 1998
LM337L
3-T
erminal
Adjustable
Regulator
1999 National Semiconductor Corporation
DS009134
www.national.com
Absolute Maximum Ratings
(Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Power Dissipation
Internally Limited
InputOutput Voltage Differential
40V
Operating Junction
Temperature Range
-25C to +125C
Storage Temperature
-55C to +150C
Lead Temperature
(Soldering, 10 sec.)
300C
Plastic Package (Soldering 4 sec.)
260C
ESD rating to be determined.
Electrical Characteristics
(Note 2)
Parameter
Conditions
Min
Typ
Max
Units
Line Regulation
T
A
= 25C, 3V
|V
IN
- V
OUT
|
40V,
0.01
0.04
%/V
(Note 3)
Load Regulation
T
A
= 25C, 5 mA
I
OUT
I
MAX
, (Note 3)
0.1
0.5
%
Thermal Regulation
T
A
= 25C, 10 ms Pulse
0.04
0.2
%/W
Adjustment Pin Current
50
100
A
Adjustment Pin Current Change
5 mA
I
L
100 mA
0.2
5
A
3V
|V
IN
- V
OUT
|
40V
Reference Voltage
3V
|V
IN
- V
OUT
|
40V, (Note 4)
1.20
1.25
1.30
V
10 mA
I
OUT
100 mA, P
625 mW
Line Regulation
3V
|V
IN
- V
OUT
|
40V, (Note 3)
0.02
0.07
%/V
Load Regulation
5 mA
I
OUT
100 mA, (Note 3)
0.3
1.5
%
Temperature Stability
T
MIN
T
j
T
MAX
0.65
%
Minimum Load Current
|V
IN
- V
OUT
|
40V
3.5
5
mA
3V
|V
IN
- V
OUT
|
15V
2.2
3.5
mA
Current Limit
3V
|V
IN
- V
OUT
|
13V
100
200
320
mA
|V
IN
- V
OUT
| = 40V
25
50
120
mA
Rms Output Noise, % of V
OUT
T
A
= 25C, 10 Hz
f
10 kHz
0.003
%
Ripple Rejection Ratio
V
OUT
= -10V, F = 120 Hz, C
ADJ
= 0
65
dB
C
ADJ
= 10 F
66
80
dB
Long-Term Stability
T
A
= 125C
0.3
1
%
Note 1: "Absolute Maximum Ratings" indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is
functional, but do not guarantee specific performance limits.
Note 2: Unless otherwise specified, these specifications apply -25C
T
j
+ 125C for the LM337L; |V
IN
- V
OUT
| = 5V and I
OUT
= 40 mA. Although power dissi-
pation is internally limited, these specifications are applicable for power dissipations up to 625 mW. I
MAX
is 100 mA.
Note 3: Regulation is measured at constant junction temperature, using pulse testing with a low duty cycle. Changes in output voltage due to heating effects are cov-
ered under the specification for thermal regulation.
Note 4: Thermal resistance of the TO-92 package is 180C/W junction to ambient with 0.4" leads from a PC board and 160C/W junction to ambient with 0.125" lead
length to PC board. The M package
JA
is 180C/W in still air.
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2
Typical Applications
1.2V-25V Adjustable Regulator
DS009134-3
Full output current not available at high input-output voltages
C1 = 1 F solid tantalum or 10 F aluminum electrolytic required for
stability
*C2 = 1 F solid tantalum is required only if regulator is more than 4" from
power supply filter capacitor
Regulator with Trimmable Output Voltage
DS009134-4
Trim Procedure:
-- If V
OUT
is -23.08V or bigger, cut out R3 (if smaller, don't cut it out).
-- Then if V
OUT
is -22.47V or bigger, cut out R4 (if smaller, don't).
-- Then if V
OUT
is -22.16V or bigger, cut out R5 (if smaller, don't).
This will trim the output to well within 1% of -22.00 V
DC
, without any of the
expense or trouble of a trim pot (see LB-46). Of course, this technique can
be used at any output voltage level.
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3
Physical Dimensions
inches (millimeters) unless otherwise noted
SO-8 Plastic Package (M)
Order Number LM337LM
NS Package Number M08A
TO-92 Plastic Package (Z)
Order Number LM337LZ
NS Package Number Z03A
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4
Notes
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whose failure to perform when properly used in
accordance with instructions for use provided in the
labeling, can be reasonably expected to result in a
significant injury to the user.
2. A critical component is any component of a life
support device or system whose failure to perform
can be reasonably expected to cause the failure of
the life support device or system, or to affect its
safety or effectiveness.
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LM337L
3-T
erminal
Adjustable
Regulator
National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications.
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