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

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

−40°C ≤ TJ ≤ +125°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

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

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

LM317MDT

LM317MDTX 2.5k Units Tape and Reel

LM317AMDT

LM317AMDTX 2.5k Units Tape and Reel

LM317MDT

LM317AMDT

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

Junction-to-Case

Thermal Resistance, θ

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

≤ 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

= 10V, f = 120 Hz, C

OUT

= 10V, f = 120 Hz, C

OUT

TJ = 125°C, 1000 hrs

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

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

0.003 %

65 dB

66 80 dB

0.3 1 %

°C/W

186

°C/W

%/V

μA

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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

vs VIN, V

OUT

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OUT

= V

REF

906367

OUT

vs VIN, V

OUT

906340

= 5V

906368

LM117/LM317A/LM317

Temperature Stability

Ripple Rejection

906341

Minimum Operating Current

906342

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.

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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