LM137/LM337
3-Terminal Adjustable Negative Regulators
General Description
The LM137/LM337 are adjustable 3-terminal negative volt-
age regulators capable of supplying in excess of -1.5A over
an output voltage range of -1.2V to -37V. These regulators
are exceptionally easy to apply, requiring only 2 external
resistors to set the output voltage and 1 output capacitor for
frequency compensation. The circuit design has been opti-
mized for excellent regulation and low thermal transients.
Further, the LM137 series features internal current limiting,
thermal shutdown and safe-area compensation, making
them virtually blowout-proof against overloads.
The LM137/LM337 serve a wide variety of applications in-
cluding local on-card regulation, programmable-output volt-
age regulation or precision current regulation. The LM137/
LM337 are ideal complements to the LM117/LM317
adjustable positive regulators.
Features
n
Output voltage adjustable from -1.2V to -37V
n
1.5A output current guaranteed, -55C to +150C
n
Line regulation typically 0.01%/V
n
Load regulation typically 0.3%
n
Excellent thermal regulation, 0.002%/W
n
77 dB ripple rejection
n
Excellent rejection of thermal transients
n
50 ppm/C temperature coefficient
n
Temperature-independent current limit
n
Internal thermal overload protection
n
P
+
Product Enhancement tested
n
Standard 3-lead transistor package
n
Output is short circuit protected
LM137 Series Packages and Power Capability
Rated
Design
Device
Package
Power
Load
Dissipation
Current
LM137/337
TO-3 (K)
20W
1.5A
TO-39 (H)
2W
0.5A
LM337
TO-220 (T)
15W
1.5A
LM337
SOT-223
(MP)
2W
1A
Typical Applications
Adjustable Negative Voltage Regulator
00906701
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
Output capacitors in the range of 1 F to 1000 F of aluminum or tantalum
electrolytic are commonly used to provide improved output impedance and
rejection of transients
Comparison between SOT-223 and
D-Pak (TO-252) Packages
00906731
Scale 1:1
November 2004
LM137/LM337
3-T
erminal
Adjustable
Negative
Regulators
2004 National Semiconductor Corporation
DS009067
www.national.com
Absolute Maximum Ratings
(Notes 1,
4)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Power Dissipation
Internally Limited
Input-Output Voltage Differential
40V
Operating Junction Temperature
Range
LM137
-55C to +150C
LM337
0C to +125C
LM337I
-40C to +125C
Storage Temperature
-65C to +150C
Lead Temperature (Soldering, 10 sec.)
300C
Plastic Package (Soldering, 4 sec.)
260C
ESD Rating
2k Volts
Electrical Characteristics
(Note 1)
Parameter
Conditions
LM137
LM337
Units
Min
Typ
Max
Min
Typ
Max
Line Regulation
T
j
= 25C, 3V
|V
IN
- V
OUT
|
40V
0.01
0.02
0.01
0.04
%/V
(Note 2) I
L
= 10 mA
Load Regulation
T
j
= 25C, 10 mA
I
OUT
I
MAX
0.3
0.5
0.3
1.0
%
Thermal Regulation
T
j
= 25C, 10 ms Pulse
0.002
0.02
0.003
0.04
%/W
Adjustment Pin Current
65
100
65
100
A
Adjustment Pin Current Charge
10 mA
I
L
I
MAX
2
5
2
5
A
3.0V
|V
IN
- V
OUT
|
40V,
T
A
= 25C
Reference Voltage
T
j
= 25C (Note 3)
-1.225 -1.250 -1.275 -1.213 -1.250 -1.287
V
3V
|V
IN
- V
OUT
|
40V, (Note 3)
-1.200 -1.250 -1.300 -1.200 -1.250 -1.300
V
10 mA
I
OUT
I
MAX
, P
P
MAX
Line Regulation
3V
|V
IN
- V
OUT
|
40V, (Note 2)
0.02
0.05
0.02
0.07
%/V
Load Regulation
10 mA
I
OUT
I
MAX
, (Note 2)
0.3
1
0.3
1.5
%
Temperature Stability
T
MIN
T
j
T
MAX
0.6
0.6
%
Minimum Load Current
|V
IN
- V
OUT
|
40V
2.5
5
2.5
10
mA
|V
IN
- V
OUT
|
10V
1.2
3
1.5
6
mA
Current Limit
|V
IN
- V
OUT
|
15V
K, MP and T Package
1.5
2.2
3.5
1.5
2.2
3.7
A
H Package
0.5
0.8
1.8
0.5
0.8
1.9
A
|V
IN
- V
OUT
| = 40V, T
j
= 25C
K, MP and T Package
0.24
0.4
0.15
0.4
A
H Package
0.15
0.17
0.10
0.17
A
RMS Output Noise, % of V
OUT
T
j
= 25C, 10 Hz
f 10 kHz
0.003
0.003
%
Ripple Rejection Ratio
V
OUT
= -10V, f = 120 Hz
60
60
dB
C
ADJ
= 10 F
66
77
66
77
dB
Long-Term Stability
T
j
= 125C, 1000 Hours
0.3
1
0.3
1
%
Thermal Resistance, Junction to
Case
H Package
12
15
12
15
C/W
K Package
2.3
3
2.3
3
C/W
T Package
4
C/W
Thermal Resistance, Junction to
Ambient (No Heat Sink)
H Package
140
140
C/W
K Package
35
35
C/W
T Package
MP Package
50
170
C/W
C/W
Note 1: Unless otherwise specified, these specifications apply -55C
T
j
+150C for the LM137, 0C T
j
+125C for the LM337; V
IN
- V
OUT
= 5V; and I
OUT
= 0.1A for the TO-39 package and I
OUT
= 0.5A for the TO-3, SOT-223 and TO-220 packages. Although power dissipation is internally limited, these specifications
are applicable for power dissipations of 2W for the TO-39 and SOT-223 (see Application Hints), and 20W for the TO-3, and TO-220. I
MAX
is 1.5A for the TO-3,
SOT-223 and TO-220 packages, and 0.2A for the TO-39 package.
Note 2: Regulation is measured at constant junction temperature, using pulse testing with a low duty cycle. Changes in output voltage due to heating effects are
covered under the specification for thermal regulation. Load regulation is measured on the output pin at a point
1
/
8
" below the base of the TO-3 and TO-39 packages.
Note 3: Selected devices with tightened tolerance reference voltage available.
LM137/LM337
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2
Electrical Characteristics
(Note 1) (Continued)
Note 4: Refer to RETS137H drawing for LM137H or RETS137K drawing for LM137K military specifications.
Schematic Diagram
00906702
Thermal Regulation
When power is dissipated in an IC, a temperature gradient
occurs across the IC chip affecting the individual IC circuit
components. With an IC regulator, this gradient can be es-
pecially severe since power dissipation is large. Thermal
regulation is the effect of these temperature gradients on
output voltage (in percentage output change) per Watt of
power change in a specified time. Thermal regulation error is
independent of electrical regulation or temperature coeffi-
cient, and occurs within 5 ms to 50 ms after a change in
power dissipation. Thermal regulation depends on IC layout
as well as electrical design. The thermal regulation of a
voltage regulator is defined as the percentage change of
V
OUT
, per Watt, within the first 10 ms after a step of power is
applied. The LM137's specification is 0.02%/W, max.
00906703
LM137, V
OUT
= -10V
V
IN
- V
OUT
= -40V
I
IL
= 0A
0.25A 0A
Vertical sensitivity, 5 mV/div
FIGURE 1.
LM137/LM337
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3
Thermal Regulation
(Continued)
In Figure 1, a typical LM137's output drifts only 3 mV (or
0.03% of V
OUT
= -10V) when a 10W pulse is applied for
10 ms. This performance is thus well inside the specification
limit of 0.02%/W x 10W = 0.2% max. When the 10W pulse is
ended, the thermal regulation again shows a 3 mV step at
the LM137 chip cools off. Note that the load regulation error
of about 8 mV (0.08%) is additional to the thermal regulation
error. In Figure 2, when the 10W pulse is applied for 100 ms,
the output drifts only slightly beyond the drift in the first
10 ms, and the thermal error stays well within 0.1% (10 mV).
Connection Diagrams
TO-3
Metal Can Package
TO-39
Metal Can Package
00906705
Case is Input
Bottom View
Order Number LM137K/883
LM137KPQML and LM137KPQMLV(Note 5)
See NS Package Number K02C
Order Number LM337K STEEL
See NS Package Number K02A
00906706
Case Is Input
Note 5: See STD Mil DWG 5962P99517 for Radiation Tolerant Devices
Bottom View
Order Number LM137H, LM137H/883 or LM337H
LM137HPQML and LM137HPQMLV(Note 5)
See NS Package Number H03A
00906704
LM137, V
OUT
= -10V
V
IN
- V
OUT
= -40V
I
L
= 0A
0.25A 0A
Horizontal sensitivity, 20 ms/div
FIGURE 2.
LM137/LM337
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4
Connection Diagrams
(Continued)
TO-220
Plastic Package
3-Lead SOT-223
00906707
Front View
Order Number LM337T
See NS Package Number T03B
00906734
Front View
Order Number LM337IMP
Package Marked N02A See NS Package Number MP04A
Application Hints
When a value for
(H-A)
is found using the equation shown,
a heatsink must be selected that has a value that is less than
or equal to this number.
HEATSINKING SOT-223 PACKAGE PARTS
The SOT-223 ("MP") packages use a copper plane on the
PCB and the PCB itself as a heatsink. To optimize the heat
sinking ability of the plane and PCB, solder the tab of the
package to the plane.
Figures 3, 4 show the information for the SOT-223 package.
Figure 4 assumes a
(J-A)
of 75C/W for 1 ounce copper and
51C/W for 2 ounce copper and a maximum junction tem-
perature of 125C.
Please see AN1028 for power enhancement techniques to
be used with the SOT-223 package.
00906732
FIGURE 3.
(J-A)
vs Copper (2 ounce) Area for the
SOT-223 Package
00906733
FIGURE 4. Maximum Power Dissipation vs. T
AMB
for
the SOT-223 Package
LM137/LM337
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