National Semiconductor LM117, LM317A, LM317 Technical data

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, the LM117 series offers full overload protection available only in IC'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 is sit­uated more than 6 inches from the input filter capacitors in 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 high ripple rejection ratios which are difficult to achieve with stan­dard 3-terminal regulators.
Besides replacing fixed regulators, the LM117 is useful in a wide 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 as long 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 a fixed resistor between the adjustment pin and output, the LM117 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.

Features

Guaranteed 1% output voltage tolerance (LM317A)
Guaranteed max. 0.01%/V line regulation (LM317A)
Guaranteed max. 0.3% load regulation (LM117)
Guaranteed 1.5A output current
Adjustable output down to 1.2V
Current limit constant with temperature
P+ Product Enhancement tested
80 dB ripple rejection
Output is short-circuit protected
LM117/LM317A/LM317 3-Terminal Adjustable Regulator
October 20, 2008

Typical Applications

1.2V–25V Adjustable Regulator
906301
Full output current not available at high input-output voltages
*Needed if device is more than 6 inches from filter capacitors.
†Optional—improves transient response. Output capacitors in the range of 1μF to 1000μF of aluminum or tantalum electrolytic are commonly used to provide improved output impedance and rejection of transients.

LM117/LM317A/LM317 Package Options

Part
Number
LM117, LM317 K TO-3 1.5A
LM317A, LM317 T TO-220 1.5A
LM317 S TO-263 1.5A
LM317A, LM317 EMP SOT-223 1.0A
LM117, LM317A, LM317 H TO-39 0.5A
LM117 E LCC 0.5A
LM317A, LM317 MDT TO-252 0.5A
Suffix Package
Current

SOT-223 vs. TO-252 (D-Pak) Packages

Scale 1:1
906354
Output
© 2008 National Semiconductor Corporation 9063 www.national.com

Connection Diagrams

Metal Can Package
LM117/LM317A/LM317
CASE IS OUTPUT
NS Package Number K02A or K02C
Surface-Mount Package
TO-3 (K)
Bottom View
Steel Package
TO-263 (S)
Top View
906330
TO-39 (H)
Metal Can Package
906331
CASE IS OUTPUT
Bottom View
NS Package Number H03A
TO-220 (T)
Plastic Package
906335
TO-263 (S)
Surface-Mount Package
Side View
906336
NS Package Number TS3B
Front View
906332
NS Package Number T03B
Ceramic Leadless
Chip Carrier (E)
Top View
NS Package Number E20A
906334
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LM117/LM317A/LM317
4-Lead SOT-223 (EMP)
Front View
NS Package Number MP04A

Ordering Information

Package
TO-3
Metal Can
(K)
TO-220 3- Lead
TO-263 3- Lead
SOT-223
4- Lead
TO-39
Metal Can
(H)
LCC
TO-252 3- Lead D-Pack
Temperature
Range
−55°C TJ +150°C
0°C TJ +125°C
−55°C TJ +150°C
−40°C TJ +125°C
0°C TJ +125°C
0°C TJ +125°C
0°C TJ +125°C
−40°C TJ +125°C
−55°C TJ +150°C
−55°C TJ +150°C
−40°C TJ +125°C
0°C TJ +125°C
−55°C TJ +150°C
0°C TJ +125°C
−40°C TJ +125°C
TO-252 (MDT)
906359
Front View
906366
NS Package Number TD03B
Output
Current
1.5A LM117K STEEL LM117K STEEL P+ 50 Per Bag
1.5A LM317K STEEL LM317K STEEL P+ 50 Per Bag
Order
Number
Package
Marking
Transport
Media
Drawing
K02A
1.5A LM117K/883 LM117K/883 50 Per Bag K02C
1.5A LM317AT LM317AT P+ 45 Units/Rail
1.5A LM317T LM317T P+ 45 Units/Rail
1.5A
1.0A
1.0A
LM317S
LM317SX 500 Units Tape and Reel
LM317EMP
LM317EMPX 2k Units Tape and Reel
LM317AEMP
LM317AEMPX 2k Units Tape and Reel
LM317S P+
N01A
N07A
45 Units/Rail
1k Units Tape and Reel
1k Units Tape and Reel
T03B
TS3B
MP04A
0.5A LM117H LM117H P+ 500 Per Box
0.5A LM117H/883 LM117H/883 20 Per Tray
0.5A LM317AH LM317AH P+ 500 Per Box
H03A
0.5A LM317H LM317H P+ 500 Per Box
0.5A LM117E/883 LM117E/883 50 Units/Rail E20A
0.5A
0.5A
LM317MDT
LM317MDTX 2.5k Units Tape and Reel
LM317AMDT
LM317AMDTX 2.5k Units Tape and Reel
LM317MDT
LM317AMDT
75 Units/Rail
75 Units/Rail
TD03B
NSC
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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 Input-Output Voltage Differential +40V, −0.3V Storage Temperature −65°C to +150°C Lead Temperature
LM117/LM317A/LM317
Metal Package (Soldering, 10 seconds) 300°C Plastic Package (Soldering, 4 seconds) 260°C ESD Tolerance (Note 5) 3 kV

Operating Temperature Range

LM117
LM317A
LM317

Preconditioning

Thermal Limit Burn-In All Devices 100%
−55°C TJ +150°C
−40°C TJ +125°C 0°C TJ +125°C

LM117 Electrical Characteristics (Note 3)

Specifications with standard type face are for TJ = 25°C, and those with boldface type apply over full Operating Temperature Range. Unless otherwise specified, VIN − V
Parameter Conditions
Reference Voltage
Line Regulation
Load Regulation
Thermal Regulation 20 ms Pulse 0.03 0.07 %/W
Adjustment Pin Current 50 100
Adjustment Pin Current Change
Temperature Stability
Minimum Load Current
Current Limit
RMS Output Noise, % of V
OUT
Ripple Rejection Ratio
Long-Term Stability
Thermal Resistance, θ
JC
Junction-to-Case
Thermal Resistance, θ
JA
Junction-to-Ambient (No Heat Sink)
= 5V, and I
OUT
3V (VIN − V 10 mA I
3V (VIN − V
10 mA I
10 mA I 3V (VIN − V
T
TJ T
MIN
(VIN − V
OUT
(VIN − V
OUT
) 40V,
OUT
I
OUT
MAX
) 40V (Note 4)
OUT
I
OUT
MAX
I
OUT
MAX
) 40V
OUT
MAX
) = 40V
) 15V
K Package H, E Package
(VIN − V
OUT
) = 40V
K Package H, E Package
10 Hz f 10 kHz
V
= 10V, f = 120 Hz, C
OUT
V
= 10V, f = 120 Hz, C
OUT
TJ = 125°C, 1000 hrs
K (TO-3) Package H (TO-39) Package E (LCC) Package
K (TO-3) Package H (TO-39) Package E (LCC) Package
= 10 mA.
OUT
(Note 4)
= 0 μF
ADJ
= 10 μF
ADJ
LM117 (Note 2)
Min Typ Max Units
1.20 1.25 1.30 V
0.01
0.02
0.1
0.3
0.02
0.05
0.3
1
0.2 5
1 %
3.5 5 mA
1.5
0.5
2.2
0.8
3.4
1.8
0.3
0.15
0.4
0.20
A
0.003 %
65 dB
66 80 dB
0.3 1 %
2
21
°C/W
12
39
186
°C/W
88
%/V
%
μA
μA
A
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LM317A and LM317 Electrical Characteristics (Note 3)

Specifications with standard type face are for TJ = 25°C, and those with boldface type apply over full Operating Temperature Range. Unless otherwise specified, VIN − V
Parameter Conditions
1.238 1.250 1.262 - 1.25
Reference Voltage
= 5V, and I
OUT
= 10 mA.
OUT
LM317A LM317
Min Typ Max Min Typ Max Units

Typical Performance Characteristics Output Capacitor = 0 μF unless otherwise noted

LM117/LM317A/LM317
Adjustment Current
Load Regulation
906337
Current Limit
906338
Dropout Voltage
906339
V
vs VIN, V
OUT
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OUT
= V
REF
906367
V
OUT
vs VIN, V
OUT
906340
= 5V
906368
LM117/LM317A/LM317
Temperature Stability
Ripple Rejection
906341
Minimum Operating Current
906342
Ripple Rejection
Ripple Rejection
906343
906345
906344
Output Impedance
906346
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Line Transient Response
LM117/LM317A/LM317
Load Transient Response
906347
906348
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LM117/LM317A/LM317

Application Hints

In operation, the LM117 develops a nominal 1.25V reference voltage, V The reference voltage is impressed across program resistor R1 and, since the voltage is constant, a constant current I then flows through the output set resistor R2, giving an output voltage of
, between the output and adjustment terminal.
REF
906305

FIGURE 1.

(1)
aluminum electrolytic) on the output swamps this effect and insures stability. Any increase of the load capacitance larger than 10 μF will merely improve the loop stability and output impedance.
1

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 240Ω) should be tied directly to the output (case) of the regulator 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 0.05Ω resis­tance between the regulator and load will have a load regu­lation due to line resistance of 0.05Ω × IL. If the set resistor is connected near the load the effective line resistance will be
0.05Ω (1 + R2/R1) or in this case, 11.5 times worse. Figure 2 shows the effect of resistance between the regulator
and 240Ω set resistor.
Since the 100μA current from the adjustment terminal repre­sents an error term, the LM117 was designed to minimize I
and make it very constant with line and load changes. To
ADJ
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 0.1μF disc or 1μF 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 is increased. With a 10 μF bypass capacitor 80dB ripple rejec­tion is obtainable at any output level. Increases over 10 μF do not appreciably improve the ripple rejection at frequencies above 120Hz. 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 at high frequencies. Depending upon capacitor construction, it takes about 25 μF in aluminum electrolytic to equal 1μF solid tan­talum at high frequencies. Ceramic capacitors are also good at high frequencies; but some types have a large decrease in capacitance at frequencies around 0.5 MHz. For this reason,
0.01 μF disc may seem to work better than a 0.1 μF disc as a bypass.
Although the LM117 is stable with no output capacitors, like any feedback circuit, certain values of external capacitance can cause excessive ringing. This occurs with values be­tween 500 pF and 5000 pF. A 1 μF solid tantalum (or 25 μF
906306

FIGURE 2. Regulator with Line Resistance in Output Lead

With the TO-3 package, it is easy to minimize the resistance from the case to the set resistor, by using two separate leads to the case. However, with the TO-39 package, care should 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 improve load regulation.

PROTECTION DIODES

When external capacitors are used with any IC regulator it is sometimes necessary to add protection diodes to prevent the capacitors from discharging through low current points into the regulator. Most 10 μF capacitors have low enough internal series resistance to deliver 20A spikes when shorted. Al­though the surge is short, there is enough energy to damage parts of the IC.
When an output capacitor is connected to a regulator and the 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, this discharge path is through a large junction that is able to sustain 15A surge with no problem. This is not true of other types of positive regulators. For output capacitors of 25 μF or less, there is no need to use diodes.
The bypass capacitor on the adjustment terminal can dis­charge through a low current junction. Discharge occurs when either the input, or the output, is shorted. Internal to the LM117 is a 50Ω resistor which limits the peak discharge current. No protection is needed for output voltages of 25V or less and 10 μF capacitance. Figure 3 shows an LM117 with protection
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