LM117/LM317A/LM317
3-Terminal Adjustable Regulator
General Description
The LM117 series of adjustable 3-terminal positive voltage
regulators is capable of supplying in excess of 1.5A over a
1.2V to 37V output range. They are exceptionally easy to
use and require only two external resistors to set the output
voltage. Further, both line and load regulation are better
than standard fixed regulators. Also, the LM117 is packaged
in standard transistor packages which are easily mounted
and handled.
In addition to higher performance than fixed regulators, theLM117 series offers full overload protection available only inIC’s. Included on the chip are current limit, thermal overload
protection and safe area protection. All overload protection
circuitry remains fully functional even if the adjustment terminal is disconnected.
Normally, no capacitors are needed unless the device issituated more than 6 inches from the input filter capacitorsin which case an input bypass is needed. An optional output
capacitor can be added to improve transient response. The
adjustment terminal can be bypassed to achieve very highripple rejection ratios which are difficult to achieve with standard 3-terminal regulators.
Besides replacing fixed regulators, the LM117 is useful in awide variety of other applications. Since the regulator is‘‘floating’’ and sees only the input-to-output differential voltage, supplies of several hundred volts can be regulated aslong as the maximum input to output differential is not exceeded, i.e., avoid short-circuiting the output.
Also, it makes an especially simple adjustable switching regulator, a programmable output regulator, or by connecting afixed resistor between the adjustment pin and output, theLM117 can be used as a precision current regulator. Supplies with electronic shutdown can be achieved by clamping

the adjustment terminal to ground which programs the output to 1.2V where most loads draw little current.
For applications requiring greater output current, see LM150
series (3A) and LM138 series (5A) data sheets. For the negative complement, see LM137 series data sheet.
LM117 Series Packages and Power Capability
Part Number
SuffixPackage

Rated
Power
Dissipation

DesignLoad
Current

K

TO-3

20W

1.5A

H

TO-39

2W

0.5A

T

TO-220

20W

1.5A

E

LCC

2W

0.5A

S

TO-2634W

1.5A

Features
Guaranteed 1% output voltage tolerance(LM317A)
Y Guaranteed max. 0.01%/V line regulation(LM317A)
Y Guaranteed max. 0.3% load regulation(LM117)
Y Guaranteed 1.5A output current
Y Adjustable output down to 1.2V
Y Current limit constant with temperature
Y P a Product Enhancement tested
Y 80 dB ripple rejection
Y Output is short-circuit protectedY

Typical Applications
1.2V–25V Adjustable Regulator

Digitally Selected Outputs

TL/H/9063 – 1

Full output current not available at high input-output voltages*Needed if device is more than 6 inches from filter capacitors.
² OptionalÐimproves transient response. Output capacitors in the range of

1 mF to 1000 mF of aluminum or tantalum electrolytic are commonly used
to provide improved output impedance and rejection of transients.
² ² VOUT e 1.25V# 1 R1 JaR2

a IADJ(R2)

C1996 National Semiconductor Corporation

TL/H/9063

TL/H/9063 – 2*Sets maximum VOUT

RRD-B30M56/Printed in U. S. A.

http://www.national.com

LM117/LM317A/LM317 3-Terminal Adjustable Regulator

May 1996

Absolute Maximum Ratings (Note 1)

Operating Temperature Range

If Military/Aerospace specified devices are required,please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
(Note 2)
Power Dissipation
Internally Limited
a 40V, b 0.3V
Input-Output Voltage Differential

LM117

b 55§ C s TJ s a 150§ C

LM317Ab 40§ C s TJ s a 125§ C

LM317

0§ C s TJ s a 125§ C

Preconditioning
Thermal Limit Burn-In

All Devices 100%b 65§ C to a 150§ C
Storage Temperature
Lead Temperature
Metal Package (Soldering, 10 seconds)
300§ C
Plastic Package (Soldering, 4 seconds)
260§ CESD Tolerance (Note 5)

3 kVElectrical Characteristics
Specifications with standard type face are for TJ e 25§ C, and those with boldface type apply over full Operating Temperature Range. Unless otherwise specified, VIN b VOUT e 5V, and IOUT e 10 mA. (Note 3)
Parameter

LM117 (Note 2)

Conditions
Min

Typ

Units
Max

Reference Voltage

V
3V s (VIN b VOUT) s 40V,
10 mA s IOUT s IMAX, P s PMAXLine Regulation

3V s (VIN b VOUT) s 40V (Note 4)

Load Regulation

10 mA s IOUT s IMAX (Note 4)

Thermal Regulation

1.20

20 ms Pulse

Adjustment Pin Current

1.25

1.30

V

0.01

0.02

%/V

0.02

0.05

%/V

0.1

0.3

%

0.3

1

%

0.03

0.07

%/W

50

100

mA

0.2

5

mA

Adjustment Pin Current Change

10 mA s IOUT s IMAX
3V s (VIN b VOUT) s 40V

Temperature Stability

TMIN s TJ s TMAX

1

Minimum Load Current(VIN b VOUT) e 40V

3.5

5

mA

Current Limit(VIN b VOUT) s 15V
K Package
H, K Packages

1.5
0.5

2.2
0.8

3.4
1.8

A
A

(VIN b VOUT) e 40V
K Package
H, K Packages

0.3
0.15

0.4
0.2

A
A

%

RMS Output Noise, % of VOUT

10 Hz s f s 10 kHz

0.003

%

Ripple Rejection Ratio

VOUT e 10V, f e 120 Hz,
CADJ e 0 mF

65

dB

80

dB

VOUT e 10V, f e 120 Hz,
CADJ e 10 mF

66

Long-Term Stability

TJ e 125§ C, 1000 hrs

0.3

1

%

Thermal Resistance,
Junction-to-Case

K Package
H Package
E Package

2.3
12

3
15

§ C/W
§ C/W
§ C/W

Thermal Resistance, Junctionto-Ambient (No Heat Sink)

K Package
H Package
E Package35
140

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2

§ C/W
§ C/W
§ C/W

Electrical Characteristics (Continued)
Specifications with standard type face are for TJ e 25§ C, and those with boldface type apply over full Operating Temperature Range. Unless otherwise specified, VIN b VOUT e 5V, and IOUT e 10 mA. (Note 3)
Parameter

LM317A

Conditions

Reference Voltage
3V s (VIN b VOUT) s 40V,
10 mA s IOUT s IMAX, P s PMAXLine Regulation

Load Regulation

Thermal Regulation

LM317

Min

Typ

Max

1.238

1.250

1.262

1.225

1.250

1.270

3V s (VIN b VOUT) s 40V (Note 4)

10 mA s IOUT s IMAX (Note 4)

20 ms Pulse

Adjustment Pin Current

Min

Typ

Units
Max
V

1.20

1.25

1.30

V

0.005

0.01

0.01

0.04

%/V

0.01

0.02

0.02

0.07

%/V
%

0.1

0.5

0.1

0.5

0.3

1

0.3

1.5

%

0.04

0.07

0.04

0.07

%/W

50

100

50

100

mA

0.2

5

0.2

5

mA

3.5

10

mA

1.5
0.5

2.2
0.8

3.4
1.8

A
A

0.15
0.075

0.4
0.2

A
A

Adjustment Pin Current Change

10 mA s IOUT s IMAX
3V s (VIN b VOUT) s 40V

Temperature Stability

TMIN s TJ s TMAX

1

Minimum Load Current(VIN b VOUT) e 40V

3.5

10

Current Limit(VIN b VOUT) s 15V
K, T Packages
H, P Packages

1.5
0.5

2.2
0.8

3.4
1.8

(VIN b VOUT) e 40V
K, T Packages
H, P Packages

0.15
0.075

0.4
0.2

1

%

RMS Output Noise, % of VOUT

10 Hz s f s 10 kHz

0.003

0.003

%

Ripple Rejection Ratio

VOUT e 10V, f e 120 Hz,
CADJ e 0 mF

65

65

dB

80

dB

VOUT e 10V, f e 120 Hz,
CADJ e 10 mF
Long-Term Stability

TJ e 125§ C, 1000 hrs

Thermal Resistance, Junctionto-Case

K Package
H Package
T Package
P Package

Thermal Resistance, Junctionto-Ambient (No Heat Sink)

K Package
H Package
T Package
P Package (Note 6)

66

80
0.3
12
4
35
140
50

66
1

0.3

1

%

15
5

2.3
12
4

3
15

§ C/W
§ C/W
§ C/W
§ C/W

35
140
50
50

§ C/W
§ C/W
§ C/W
§ C/W

Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device isintended to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics.
The guaranteed specifications apply only for the test conditions listed.
Note 2: Refer to RETS117H drawing for the LM117H, or the RETS117K for the LM117K military specifications.
Note 3: Although power dissipation is internally limited, these specifications are applicable for maximum power dissipations of 2W for the TO-39 and 20W for the
TO-3 and TO-220. IMAX is 1.5A for the TO-3 and TO-220 packages and 0.5A for the TO-39 package. All limits (i.e., the numbers in the Min. and Max. columns) areguaranteed to National’s AOQL (Average Outgoing Quality Level).
Note 4: Regulation is measured at a constant junction temperature, using pulse testing with a low duty cycle. Changes in output voltage due to heating effects arecovered under the specifications for thermal regulation.
Note 5: Human body model, 100 pF discharged through a 1.5 kX resistor.
Note 6: If the TO-263 package is used, the thermal resistance can be reduced by increasing the PC board copper area thermally connected to the package: Using
0.5 square inches of copper area. iJA is 50§ C/W; with 1 square inch of copper area, iJA is 37§ C/W; and with 1.6 or more square inches of copper area, iJA is32§ C/W.

3

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Typical Performance Characteristics
Output Capacitor e 0 mF unless otherwise noted
Load Regulation

Current Limit

Adjustment Current

Dropout Voltage

Temperature Stability

Minimum Operating Current

Ripple Rejection

Ripple Rejection

Ripple Rejection

Output ImpedanceLine Transient Response

Load Transient Response

TL/H/9063 – 4

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4Application Hints
tween 500 pF and 5000 pF. A 1 mF solid tantalum (or 25 mF
aluminum electrolytic) on the output swamps this effect andinsures stability. Any increase of the load capacitance larger
than 10 mF will merely improve the loop stability and output
impedance.

In operation, the LM117 develops a nominal 1.25V reference voltage, VREF, between the output and adjustment terminal. The reference voltage is impressed across program
resistor R1 and, since the voltage is constant, a constantcurrent I1 then flows through the output set resistor R2, giving an output voltage of
VOUT e VREF

#

1a

R2
R1

J

Load Regulation
The LM117 is capable of providing extremely good load regulation but a few precautions are needed to obtain maximum performance. The current set resistor connected between the adjustment terminal and the output terminal (usually 240X) should be tied directly to the output (case) of theregulator rather than near the load. This eliminates line
drops from appearing effectively in series with the reference
and degrading regulation. For example, a 15V regulator with
0.05X resistance between the regulator and load will have aload regulation due to line resistance of 0.05X c IL. If theset resistor is connected near the load the effective line
resistance will be 0.05X (1 a R2/R1) or in this case, 11.5
times worse.

a IADJR2

Figure 2 shows the effect of resistance between the regulator and 240X set resistor.
TL/H/9063 – 5

FIGURE 1
Since the 100 mA current from the adjustment terminal represents an error term, the LM117 was designed to minimize
IADJ and make it very constant with line and load changes.
To do this, all quiescent operating current is returned to the
output establishing a minimum load current requirement. If
there is insufficient load on the output, the output will rise.
External Capacitors
An input bypass capacitor is recommended. A 0.1 mF discor 1 mF solid tantalum on the input is suitable input bypassing for almost all applications. The device is more sensitive
to the absence of input bypassing when adjustment or output capacitors are used but the above values will eliminate
the possibility of problems.
The adjustment terminal can be bypassed to ground on the
LM117 to improve ripple rejection. This bypass capacitor
prevents ripple from being amplified as the output voltage isincreased. With a 10 mF bypass capacitor 80 dB ripple rejection is obtainable at any output level. Increases over
10 mF do not appreciably improve the ripple rejection at
frequencies above 120 Hz. If the bypass capacitor is used, it
is sometimes necessary to include protection diodes to prevent the capacitor from discharging through internal low current paths and damaging the device.
In general, the best type of capacitors to use is solid tantalum. Solid tantalum capacitors have low impedance even athigh frequencies. Depending upon capacitor construction, it
takes about 25 mF in aluminum electrolytic to equal 1 mF
solid tantalum at high frequencies. Ceramic capacitors arealso good at high frequencies; but some types have a large
decrease in capacitance at frequencies around 0.5 MHz.
For this reason, 0.01 mF disc may seem to work better thana 0.1 mF disc as a bypass.
Although the LM117 is stable with no output capacitors, likeany feedback circuit, certain values of external capacitancecan cause excessive ringing. This occurs with values be-

TL/H/9063 – 6

FIGURE 2. Regulator with Line Resistancein Output Lead
With the TO-3 package, it is easy to minimize the resistancefrom the case to the set resistor, by using two separate
leads to the case. However, with the TO-5 package, careshould be taken to minimize the wire length of the output
lead. The ground of R2 can be returned near the ground of
the load to provide remote ground sensing and improveload regulation.
Protection Diodes
When external capacitors are used with any IC regulator it issometimes necessary to add protection diodes to preventthe capacitors from discharging through low current points
into the regulator. Most 10 mF capacitors have low enoughinternal series resistance to deliver 20A spikes when shorted. Although the surge is short, there is enough energy todamage parts of the IC.
When an output capacitor is connected to a regulator andthe input is shorted, the output capacitor will discharge into
the output of the regulator. The discharge current depends
on the value of the capacitor, the output voltage of the regulator, and the rate of decrease of VIN. In the LM117, thisdischarge path is through a large junction that is able tosustain 15A surge with no problem. This is not true of othertypes of positive regulators. For output capacitors of 25 mF
or less, there is no need to use diodes.

5

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Application Hints (Continued)
current. No protection is needed for output voltages of 25Vor less and 10 mF capacitance. Figure 3 shows an LM117
with protection diodes included for use with outputs greaterthan 25V and high values of output capacitance.

The bypass capacitor on the adjustment terminal can discharge through a low current junction. Discharge occurs
when either the input or output is shorted. Internal to theLM117 is a 50X resistor which limits the peak discharge

VOUT e 1.25V# 1 R1 JaR2

a IADJR2

D1 protects against C1D2 protects against C2

TL/H/9063 – 7

FIGURE 3. Regulator with Protection Diodes

Schematic Diagram

TL/H/9063 – 8

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6

Typical Applications (Continued)
Slow Turn-On 15V Regulator

5V Logic Regulator with Electronic Shutdown**Min. output & 1.2V

TL/H/9063 – 9

TL/H/9063 – 3Adjustable Regulator with Improved
Ripple Rejection

High Stability 10V Regulator² Solid tantalum*Discharges C1 if output is shorted to ground

TL/H/9063 – 10

TL/H/9063 – 11High Current Adjustable Regulator² Solid tantalum*Minimum load current e 30 mA

TL/H/9063 – 12

³ OptionalÐimproves ripple rejection

7

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Typical Applications (Continued)
Power Follower

0 to 30V Regulator

Full output current not available at high input-output voltages

TL/H/9063–13

TL/H/9063 – 14

5A Constant Voltage/Constant Current Regulator² Solid tantalum

TL/H/9063 – 15

*Lights in constant current mode

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Typical Applications (Continued)
1A Current Regulator

1.2V – 20V Regulator with
Minimum Program Current

TL/H/9063–16

High Gain Amplifier

TL/H/9063 – 17

*Minimum load current & 4 mA

TL/H/9063 – 18

Low Cost 3A Switching Regulator² Solid tantalum

TL/H/9063 – 19*CoreÐArnold A-254168-2 60 turns

4A Switching Regulator with Overload Protection

Precision Current Limiter

TL/H/9063 – 21

² Solid tantalum*CoreÐArnold A-254168-2 60 turns

TL/H/9063 – 209

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Typical Applications (Continued)
Tracking Preregulator

TL/H/9063 – 22

Current Limited Voltage Regulatorb Short circuit current is approximately

600 mV, or 120 mA
R3

TL/H/9063 – 23(Compared to LM117’s higher current limit)b At 50 mA output only */4 volt of drop occurs in R3 and R4

Adjusting Multiple On-Card Regulators with Single Control**All outputs within g 100 mV² Minimum loadÐ10 mA

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TL/H/9063 – 24

Typical Applications (Continued)
AC Voltage Regulator

50 mA Constant Current Battery Charger

TL/H/9063 – 27

Adjustable 4A Regulator

TL/H/9063 – 25

12V Battery Charger

TL/H/9063 – 26

*RSÐsets output impedance of charger: ZOUT e RS

#

1a

R2
R1

J

Use of RS allows low charging rates with fully charged battery.
TL/H/9063 – 28

Current Limited 6V Charger*Sets peak current (0.6A for 1X)**The 1000 mF is recommended to filter out input
transients

TL/H/9063 – 2911

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Connection Diagrams(TO-39)
Metal Can Package(TO-3)
Metal Can Package

CASE IS OUTPUT
CASE IS OUTPUT
TL/H/9063–30

Order Number LM117H, LM117H/883,
LM317AH or LM317H
See NS Package Number H03A

Bottom View
Steel Package
Order Number LM117K STEELor LM317K STEEL
See NS Package Number K02A
Order Number LM117K/883
See NS Package Number K02C

(TO-220)
Plastic Package

TL/H/9063 – 31

Bottom View

(TO-263) Surface-Mount Package

TL/H/9063 – 35

Top View

TL/H/9063 – 36

Top View

Order Number LM317S
See NS Package Number TS3B

Order Number LM117E/883
See NS Package Number E20A

TL/H/9063–32

Front View
Order Number LM317AT or LM317T
See NS Package Number T03B

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TL/H/9063 – 34

Side View

12

Physical Dimensions inches (millimeters) unless otherwise noted

Order Number LM117E/883
NS Package Number E20A

(TO-39) Metal Can Package
Order Number LM117H, LM117H/883, LM317AH or LM317H
NS Package Number H03A
13

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Physical Dimensions inches (millimeters) unless otherwise noted (Continued)

TO-3 Metal Can Package (K)Order Number LM117K STEEL,
LM117K STEEL/883, or LM317K STEELNS Package Number K02A

TO-3 Metal Can Package (K)Mil-Aero Product
Order Number LM117K/883
NS Package Number K02C

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14

Physical Dimensions inches, (millimeters) (Continued)(TO-220) Outline Drawing
Order Number LM317AT or LM317T
NS Package Number T03B

15

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LM117/LM317A/LM317 3-Terminal Adjustable Regulator

Physical Dimensions inches, (millimeters) (Continued)

Order Number LM317S
NS Package Number TS3B

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