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An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,

intellectual property matters and other important disclaimers. PRODUCTION DATA.

LM317-N-MIL

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LM317-N-MIL Wide Temperature Three-Pin Adjustable Regulator

1 Features

1• Typ. 0.1% Load Regulation

• Typ. 0.01%/V Line Regulation

• 1.5-A Output Current

• Adjustable Output Down to 1.25 V

• Current Limit Constant With Temperature

• 80-dB Ripple Rejection

• Short-Circuit Protected Output

2 Applications

• Automotive LED Lighting

• Battery Chargers

• Post Regulation for Switching Supplies

• Constant Current Regulators

• Microprocessor Supplies

Typical Application

*Needed if device is more than 6 inches from filter

capacitors.

†Optional—improves transient response

††

3 Description

The LM317-N-MIL adjustable 3-pin positive voltage

regulator is capable of supplying in excess of 1.5 A

over a 1.25-V to 37-V output range and a wide

temperature range. The LM317-N-MIL is easy to use

and requires only two external resistors to set the

output voltage. Further, both line and load regulation

are better than standard fixed regulators.

The LM317-N-MIL offers full overload protection,

such as current limit, thermal overload protection, and

safe area protection. All overload protection circuitry

remains fully functional even if the adjustment

terminal is disconnected.

Typically, 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

that are difficult to achieve with standard 3-terminal

regulators.

Because the regulator is floating and detects 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.

That is, avoid short-circuiting the output.

By connecting a fixed resistor between the

adjustment pin and output, the LM317-N-MIL can be

also 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 1.25 V where most loads draw

little current.

For applications requiring greater output current, see

data sheets for LM150 series (3 A), SNVS772, and

LM138 series (5 A), SNVS771. For the negative

complement, see LM137 (SNVS778) series data

sheet.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (NOM)

LM317-N-MIL

TO-3 (2) 38.94 mm x 25.40 mm

TO-220 (3) 14.986 mm × 10.16 mm

TO-263 (3) 10.18 mm × 8.41 mm

SOT-223 (4) 6.50 mm × 3.50 mm

TO (3) 8.255 mm × 8.255 mm

TO-252 (3) 6.58 mm × 6.10 mm

(1) For all available packages, see the orderable addendum at

the end of the data sheet.

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Table of Contents

1 Features.................................................................. 1

2 Applications ........................................................... 1

3 Description............................................................. 1

4 Revision History..................................................... 2

5 Pin Configuration and Functions......................... 2

6 Specifications......................................................... 4

6.1 Absolute Maximum Ratings ...................................... 4

6.2 ESD Ratings.............................................................. 4

6.3 Recommended Operating Conditions....................... 4

6.4 Thermal Information.................................................. 5

6.5 Electrical Characteristics........................................... 6

6.6 Typical Characteristics.............................................. 7

7 Detailed Description............................................ 10

7.1 Overview................................................................. 10

7.2 Functional Block Diagram....................................... 11

7.3 Feature Description................................................. 12

7.4 Device Functional Modes........................................ 12

8 Application and Implementation ........................ 14

8.1 Application Information............................................ 14

8.2 Typical Applications ................................................ 14

9 Power Supply Recommendations...................... 26

10 Layout................................................................... 26

10.1 Layout Guidelines ................................................. 26

10.2 Layout Example .................................................... 26

10.3 Thermal Considerations........................................ 27

11 Device and Documentation Support................. 34

11.1 Documentation Support ........................................ 34

11.2 Related Links ........................................................ 34

11.3 Community Resources.......................................... 34

11.4 Trademarks........................................................... 34

11.5 Electrostatic Discharge Caution............................ 34

11.6 Glossary................................................................ 34

12 Mechanical, Packaging, and Orderable

Information........................................................... 34

4 Revision History

DATE REVISION NOTES

June 2017 * Initial Release

5 Pin Configuration and Functions

NDS Metal Can Package

2-Pin TO-3

Bottom View

Case is Output

NDT Metal Can Package

3-Pin TO

Bottom View

Case is Output

Pin Functions, Metal Can Packages

PIN I/O DESCRIPTION

NAME TO-3 TO

ADJ 1 2 — Adjust pin

VOUT CASE 3, CASE O Output voltage pin for the regulator

VIN 2 1 I Input voltage pin for the regulator

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KTT Surface-Mount Package

3-Pin DDPAK/TO-263

Top View

NDE Plastic Package

3-Pin TO-220

Front View

DCY Surface-Mount Package

4-Pin SOT-223

Top View

NDP Surface-Mount Package

3-Pin TO-252

Front View

Pin Functions

PIN I/O DESCRIPTION

NAME TO-263 TO-220 SOT-223 TO-252

ADJ 1 1 1 1 — Adjust pin

VOUT 2, TAB 2, TAB 2, 4 2, TAB O Output voltage pin for the regulator

VIN 3 3 3 3 I Input voltage pin for the regulator

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(1) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings

only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended

Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.

(2) If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/Distributors for availability and

specifications.

6 Specifications

6.1 Absolute Maximum Ratings

over operating free-air temperature range (unless otherwise noted)(1)(2)

MIN MAX UNIT

Power dissipation Internally Limited

Input-output voltage differential −0.3 40 V

Lead temperature Metal package (soldering, 10 seconds) 300 °C

Plastic package (soldering, 4 seconds) 260 °C

Storage temperature, Tstg −65 150 °C

(1) Manufacturing with less than 500-V HBM is possible with the necessary precautions. Pins listed as ±3000 V may actually have higher

performance.

6.2 ESD Ratings VALUE UNIT

V(ESD) Electrostatic

discharge Human-body model (HBM)(1) ±3000 V

6.3 Recommended Operating Conditions

over operating free-air temperature range (unless otherwise noted) MIN MAX UNIT

Operating temperature (LM117) −55 150 °C

Operating temperature (LM317-N) 0 125 °C

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(1) For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application

report, SPRA953.

(2) When surface mount packages are used (SOT-223, TO-252), the junction to ambient thermal resistance can be reduced by increasing

the PCB copper area that is thermally connected to the package. See Heatsink Requirements for heatsink techniques.

(3) No heatsink

6.4 Thermal Information

THERMAL METRIC(1)(2)

LM317-N

UNIT

KTT

(TO-263) NDE

(TO-220) DCY

(SOT-223) NDT

(TO) NDP

(TO-252)

3 PINS 3 PINS 4 PINS 3 PINS 3 PINS

RθJA Junction-to-ambient thermal resistance 41.0 23.3 59.6 186(3) 54 °C/W

RθJC(top) Junction-to-case (top) thermal resistance 43.6 16.2 39.3 21 51.3 °C/W

RθJB Junction-to-board thermal resistance 23.6 4.9 8.4 — 28.6 °C/W

ψJT Junction-to-top characterization parameter 10.4 2.7 1.8 — 3.9 °C/W

ψJB Junction-to-board characterization parameter 22.6 4.9 8.3 — 28.1 °C/W

RθJC(bot) Junction-to-case (bottom) thermal resistance 0.9 1.1 — — 0.9 °C/W

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(1) IMAX = 1.5 A for the NDS (TO-3), NDE (TO-220), and KTT (TO-263) packages. IMAX = 1.0 A for the DCY (SOT-223) package.

IMAX = 0.5 A for the NDT (TO) and NDP (TO-252) packages. Device power dissipation (PD) is limited by ambient temperature (TA),

device maximum junction temperature (TJ), and package thermal resistance (θJA). The maximum allowable power dissipation at any

temperature is : PD(MAX) = ((TJ(MAX) – TA) / θJA). All Min. and Max. limits are ensured to TI's Average Outgoing Quality Level (AOQL).

(2) Regulation is measured at a constant junction temperature, using pulse testing with a low duty cycle. Changes in output voltage due to

heating effects are covered under the specifications for thermal regulation.

6.5 Electrical Characteristics(1)

Some specifications apply over full Operating Temperature Range as noted. Unless otherwise specified, TJ= 25°C, VIN −

VOUT = 5 V, and IOUT = 10 mA.

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

Reference voltage

TJ= 25°C 1.25 V

3 V ≤(VIN −VOUT)≤40 V,

10 mA ≤IOUT ≤IMAX(1) (over Full Operating Temperature

Range) 1.2 1.25 1.3 V

Line regulation 3V ≤(VIN −VOUT)≤40 V(2) TJ= 25°C 0.01 0.04 %/V

(over full operating

temperature range) 0.02 0.07

Load regulation 10 mA ≤IOUT ≤IMAX(1)(2) TJ= 25°C 0.1% 0.5%

(over full operating

temperature range) 0.3% 1.5%

Thermal regulation 20-ms pulse 0.04 0.07 %/W

Adjustment pin current (over full operating temperature range) 50 100 μA

Adjustment pin current change 10 mA ≤IOUT ≤IMAX(1)

3V ≤(VIN −VOUT)≤40V (over full operating

temperature range) 0.2 5 μA

Temperature stability TMIN ≤TJ≤TMAX (over full operating

temperature range) 1%

Minimum load current (VIN −VOUT) = 40 V (over full operating

temperature range) 3.5 10 mA

Current limit

(VIN −VOUT)≤15 V

TO-3, TO-263 Packages

(over full operating

temperature range) 1.5 2.2 3.4

SOT-223, TO-220

Packages (over full

operating temperature

range) 1.5 2.2 3.4

TO, TO-252 Package (over

full operating temperature

range) 0.5 0.8 1.8

(VIN −VOUT) = 40 V TO-3, TO-263 packages 0.15 0.4 ASOT-223, TO-220 packages 0.15 0.4

TO, TO-252 package 0.075 0.2

RMS output noise, % of VOUT 10 Hz ≤f≤10 kHz 0.003%

Ripple rejection ratio

VOUT = 10 V, f = 120 Hz, CADJ = 0 μF (over full operating

temperature range) 65 dB

VOUT = 10V, f = 120 Hz, CADJ = 10 μF (over full operating

temperature range) 66 80 dB

Long-term stability TJ= 125°C, 1000 hrs 0.3% 1%

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6.6 Typical Characteristics

Output Capacitor = 0 μF, unless otherwise noted.

Figure 1. Load Regulation Figure 2. Current Limit

Figure 3. Adjustment Current Figure 4. Dropout Voltage

Figure 5. VOUT vs VIN, VOUT = VREF Figure 6. VOUT vs VIN, VOUT = 5 V

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Typical Characteristics (continued)

Output Capacitor = 0 μF, unless otherwise noted.

Figure 7. Temperature Stability Figure 8. Minimum Operating Current

Figure 9. Ripple Rejection Figure 10. Ripple Rejection

Figure 11. Ripple Rejection Figure 12. Output Impedance

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Typical Characteristics (continued)

Output Capacitor = 0 μF, unless otherwise noted.

Figure 13. Line Transient Response Figure 14. Load Transient Response

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OUT ADJ

V = 1.25 V I R

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7 Detailed Description

7.1 Overview

In operation, the LM317-N-MIL develops a nominal 1.25-V reference voltage, VREF, between the output and

adjustment terminal. The reference voltage is impressed across program resistor R1 and, because the voltage is

constant, a constant current I1then flows through the output set resistor R2, giving an output voltage calculated

by Equation 1:

(1)

Figure 15. Setting the VOUT Voltage

Because the 100-μA current from the adjustment terminal represents an error term, the LM317-N-MIL 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.

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7.2 Functional Block Diagram

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7.3 Feature Description

7.3.1 Load Regulation

The LM317-N-MIL is capable of providing extremely good load regulation but a few precautions are needed to

obtain maximum performance. The current set resistor, R1, must be connected near the output terminal of the

regulator rather than near the load. If R1 is placed too far from the output terminal, then the increased trace

resistance, RS, will cause an error voltage drop in the adjustment loop and degrade load regulation performance.

Therefore, R1 must be placed as close as possible to the output terminal to minimize RSand maximize load

regulation performance.

Figure 16 shows the effect of the trace resistance, RS, when R1 is placed far from the output terminal of the

regulator. It is clear that RSwill cause an error voltage drop especially during higher current loads, so it is

important to minimize the RStrace resistance by keeping R1 close to the regulator output terminal.

Figure 16. 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 package, care must 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.

7.4 Device Functional Modes

7.4.1 External Capacitors

An input bypass capacitor is recommended. A 0.1-μF disc or 1-μF 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 LM317-N-MIL to improve ripple rejection. This

bypass capacitor prevents ripple from being amplified as the output voltage is increased. With a 10-μF bypass

capacitor, 80-dB ripple rejection is obtainable at any output level. Increases over 10 μF 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 at high frequencies. Depending upon capacitor construction, it takes about 25 μF in aluminum electrolytic to

equal 1-μF solid tantalum at high frequencies. Ceramic capacitors are also good at high frequencies. However,

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 LM317-N-MIL 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 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.

( )

OUT ADJ

V = 1.25 V I R

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Device Functional Modes (continued)

7.4.2 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 20-A 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 LM317-N-MIL, this discharge path is through a large

junction that is able to sustain 15-A 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 LM317-N-MIL is a 50-Ωresistor which limits the

peak discharge current. No protection is needed for output voltages of 25 V or less and 10-μF capacitance.

Figure 17 shows an LM317-N-MIL with protection diodes included for use with outputs greater than 25 V and

high values of output capacitance.

D1 protects against C1

D2 protects against C2

Figure 17. Regulator With Protection Diodes

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8 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component

specification, and TI does not warrant its accuracy or completeness. TI’s customers are

responsible for determining suitability of components for their purposes. Customers must

validate and test their design implementation to confirm system functionality.

8.1 Application Information

The LM317-N-MIL is a versatile, high performance, linear regulator with high accuracy and a wide temperature

range. An output capacitor can be added to further improve transient response, and the ADJ pin can be

bypassed to achieve very high ripple-rejection ratios. Its functionality can be utilized in many different

applications that require high performance regulation, such as battery chargers, constant current regulators, and

microprocessor supplies.

8.2 Typical Applications

8.2.1 1.25-V to 25-V Adjustable Regulator

The device can be used as a simple, low-dropout regulator to enable a variety of output voltages needed for

demanding applications. By using an adjustable R2 resistor, a variety of output voltages can be made possible

as shown in Figure 18.

NOTE: 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 1 μF to 1000 μF of aluminum or tantalum

electrolytic are commonly used to provide improved output impedance and rejection of transients.

Figure 18. 1.25-V to 25-V Adjustable Regulator

8.2.1.1 Design Requirements

The device component count is very minimal, employing two resistors as part of a voltage divider circuit and an

output capacitor for load regulation. An input capacitor is needed if the device is more than 6 inches from filter

capacitors. An optional bypass capacitor across R2 can also be used to improve PSRR.

8.2.1.2 Detailed Design Procedure

The output voltage is set based on the selection of the two resistors, R1 and R2, as shown in Figure 18. For

details on capacitor selection, refer to External Capacitors.

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Typical Applications (continued)

8.2.1.3 Application Curve

As shown in Figure 19, VOUT will rise with VIN minus some dropout voltage. This dropout voltage during startup

will vary with ROUT.

Figure 19. VOUT vs VIN, VOUT = 5V

8.2.2 5-V Logic Regulator With Electronic Shutdown

Figure 20 shows a variation of the 5-V output regulator application uses the device along with an NPN transistor

to provide shutdown control. The NPN will either block or sink the current from the ADJ pin by responding to the

TTL pin logic. When TTL is pulled high, the NPN is on and pulls the ADJ pin to GND, and the LM117 outputs

about

1.25 V. When TTL is pulled low, the NPN is off and the regulator outputs according to the programmed

adjustable voltage.

NOTE: Min. output ≊1.2 V

Figure 20. 5-V Logic Regulator With Electronic Shutdown

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Typical Applications (continued)

8.2.3 Slow Turnon 15-V Regulator

An application of the device includes a PNP transistor with a capacitor to implement slow turnon functionality

(see Figure 21). As VIN rises, the PNP sinks current from the ADJ rail. The output voltage at start up is the

addition of the 1.25-V reference plus the drop across the base to emitter. While this is happening, the capacitor

begins to charge and eventually opens the PNP. At this point, the device functions normally, regulating the

output at 15 V. A diode is placed between C1 and VOUT to provide a path for the capacitor to discharge. Such

controlled turnon is useful for limiting the in-rush current.

Figure 21. Slow Turnon 15-V Regulator

267 

1.5 k

2 k

0.1 µF

LM329

VIN

15 V VOUT

10 V

VIN VOUT

ADJ

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Typical Applications (continued)

8.2.4 Adjustable Regulator With Improved Ripple Rejection

To improve ripple rejection, a capacitor is used to bypass the ADJ pin to GND (see Figure 22). This is used to

smooth output ripple by cleaning the feedback path and stopping unnecessary noise from being fed back into the

device, propagating the noise.

NOTE: †Solid tantalum

*Discharges C1 if output is shorted to ground

Figure 22. Adjustable Regulator With Improved Ripple Rejection

8.2.5 High Stability 10-V Regulator

Using a high stability shunt voltage reference in the feedback path, such as the LM329, provides damping

necessary for a stable, low noise output (see Figure 23).

Figure 23. High Stability 10-V Regulator

three LM195 devices in parallel

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Typical Applications (continued)

8.2.6 High-Current Adjustable Regulator

Using the LM195 power transistor in parallel with the device can increase the maximum possible output load

current (see Figure 24). Sense resistor R1 provides the 0.6 V across base to emitter to turn on the PNP. This on

switch allows current to flow, and the voltage drop across R3 drives three LM195 power transistors designed to

carry an excess of 1 A each.

NOTE

The selection of R1 determines a minimum load current for the PNP to turn on. The higher

the resistor value, the lower the load current must be before the transistors turn on.

NOTE: ‡Optional—improves ripple rejection

†Solid tantalum

*Minimum load current = 30 mA

Figure 24. High-Current Adjustable Regulator

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Typical Applications (continued)

8.2.7 Emitter-Follower Current Amplifier

The device is used as a constant current source in the emitter follower circuit (see Figure 25). The LM195 power

transistor is being used as a current gain amplifier, boosting the INPUT current. The device provides a stable

current bias than just using a resistor.

Figure 25. Emitter-Follower Current Amplifier

8.2.8 1-A Current Regulator

A simple, fixed current regulator can be made by placing a resistor between the VOUT and ADJ pins of the device

(see Figure 26). By regulating a constant 1.25 V between these two terminals, a constant current is delivered to

the load.

Figure 26. 1-A Current Regulator

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Typical Applications (continued)

8.2.9 Common-Emitter Amplifier

Sometimes it is necessary to use a power transistor for high current gain. In this case, the device provides

constant current at the collector of the LM195 in this common emitter application (see Figure 27). The 1.25-V

reference between VOUT and ADJ is maintained across the 2.4-Ωresistor, providing about 500-mA constant bias

current into the collector of the LM195.

Figure 27. Common-Emitter Amplifier

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Typical Applications (continued)

8.2.10 Low-Cost 3-A Switching Regulator

The LM317-N-MIL can be used in a switching buck regulator application in cost sensitive applications that require

high efficiency. The switch node above D1 oscillates between ground and VIN, as the voltage across sense

resistor R1 drives the power transistor on and off. Figure 28 exhibits self-oscillating behavior by negative

feedback through R6 and C3 to the ADJ pin of the LM317-N-MIL.

NOTE: †Solid tantalum

*Core—Arnold A-254168-2 60 turns

Figure 28. Low-Cost 3-A Switching Regulator

Short circuit current is approximately , or 210 mA

600

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Typical Applications (continued)

8.2.11 Current-Limited Voltage Regulator

A maximum limit on output current can be set using the circuit shown in Figure 29. The load current travels

through R3 and R4. As the load current increases, the voltage drop across R3 increases until the NPN transistor

is driven, during which the ADJ pin is pulled down to ground and the output voltage is pulled down to the

reference voltage of 1.25 V.

(Compared to the higher current limit of the device)

—At 50 mA output only ¾ volt of drop occurs in R3and R4

Figure 29. Current-Limited Voltage Regulator

8.2.12 Adjusting Multiple On-Card Regulators With Single Control

Figure 30 shows how multiple LM317-N-MIL regulators can be controlled by setting one resistor. Because each

device maintains the reference voltage of about 1.25 V between its VOUT and ADJ pins, we can connect each

ADJ rail to a single resistor, setting the same output voltage across all devices. This allows for independent

outputs, each responding to its corresponding input only. Designers must also consider that by the nature of the

circuit, changes to R1 and R2 affect all regulators.

NOTE: *All outputs within ±100 mV

†Minimum load—10 mA

Figure 30. Adjusting Multiple On-Card Regulators With Single Control

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Typical Applications (continued)

8.2.13 AC Voltage Regulator

In Figure 31, the top regulator is +6 V above the bottom regulator. It is clear that when the input rises above +6 V

plus the dropout voltage, only the top LM317-N-MIL regulates +6 V at the output. When the input falls below –6 V

minus the dropout voltage, only the bottom LM317-N-MIL regulates –6 V at the output. For regions where the

output is not clipped, there is no regulation taking place, so the output follows the input.

Figure 31. AC Voltage Regulator

8.2.14 12-V Battery Charger

The LM317-N-MIL can be used in a battery charger application shown in Figure 32, where the device maintains

either constant voltage or constant current mode depending on the current charge of the battery. To do this, the

part senses the voltage drop across the battery and delivers the maximum charging current necessary to charge

the battery. When the battery charge is low, there exists a voltage drop across the sense resistor RS, providing

constant current to the battery at that instant. As the battery approaches full charge, the potential drop across RS

approaches zero, reducing the current and maintaining the fixed voltage of the battery.

Use of RSallows low charging rates with fully charged battery.

Figure 32. 12-V Battery Charger

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Typical Applications (continued)

8.2.15 Adjustable 4-A Regulator

Using three LM317-N-MIL devices in parallel increases load current capability (Figure 33). Output voltage is set

by the variable resistor tied to the non-inverting terminal of the operational amplifier, and reference current to the

transistor is developed across the 100-Ωresistor. When output voltage rises, the operational amplifier corrects by

drawing current from the base, closing the transistor. This effectively pulls ADJ down and lowers the output

voltage through negative feedback.

Figure 33. Adjustable 4-A Regulator

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Typical Applications (continued)

8.2.16 Current-Limited 6-V Charger

The current in a battery charger application is limited by switching between constant current and constant voltage

states (see Figure 34). When the battery pulls low current, the drop across the 1-Ωresistor is not substantial and

the NPN remains off. A constant voltage is seen across the battery, as regulated by the resistor divider. When

current through the battery rises past peak current, the 1 Ωprovides enough voltage to turn the transistor on,

pulling ADJ close to ground. This results in limiting the maximum current to the battery.

*Sets peak current (0.6A for 1Ω)

**The 1000-μF is recommended to filter out input transients

Figure 34. Current-Limited 6-V Charger

8.2.17 Digitally Selected Outputs

Figure 35 demonstrates a digitally selectable output voltage. In its default state, all transistors are off and the

output voltage is set based on R1 and R2. By driving certain transistors, the associated resistor is connected in

parallel to R2, modifying the output voltage of the regulator.

*Sets maximum VOUT

Figure 35. Digitally Selected Outputs

(2)

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9 Power Supply Recommendations

The input supply to the LM317-N-MIL must be kept at a voltage level such that its maximum input to output

differential voltage is not exceeded. The minimum dropout voltage must also be met with extra headroom when

possible to keep the LM317-N-MIL in regulation. An input capacitor is recommended, especially when the input

pin is located more than 6 inches away from the power supply source. For more information regarding capacitor

selection, refer to External Capacitors.

10 Layout

10.1 Layout Guidelines

Some layout guidelines must be followed to ensure proper regulation of the output voltage with minimum noise.

Traces carrying the load current must be wide to reduce the amount of parasitic trace inductance and the

feedback loop from VOUT to ADJ must be kept as short as possible. To improve PSRR, a bypass capacitor can

be placed at the ADJ pin and must be located as close as possible to the IC. In cases when VIN shorts to ground,

an external diode must be placed from VOUT to VIN to divert the surge current from the output capacitor and

protect the IC. Similarly, in cases when a large bypass capacitor is placed at the ADJ pin and VOUT shorts to

ground, an external diode must be placed from ADJ to VOUT to provide a path for the bypass capacitor to

discharge. These diodes must be placed close to the corresponding IC pins to increase their effectiveness.

10.2 Layout Example

Figure 36. Layout Example (SOT-223)

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Layout Example (continued)

Figure 37. Layout Example (TO-220)

10.3 Thermal Considerations

10.3.1 Heatsink Requirements

The LM317-N-MIL regulators have internal thermal shutdown to protect the device from over-heating. Under all

operating conditions, the junction temperature of the LM317-N-MIL must not exceed the rated maximum junction

temperature (TJ) of 125°C. A heatsink may be required depending on the maximum device power dissipation and

the maximum ambient temperature of the application. To determine if a heatsink is needed, the power dissipated

by the regulator, PD, must be calculate with Equation 3:

PD= ((VIN −VOUT) × IL) + (VIN × IG) (3)

Figure 38 shows the voltage and currents which are present in the circuit.

The next parameter which must be calculated is the maximum allowable temperature rise, TR(MAX) in Equation 4:

TR(MAX) = TJ(MAX) −TA(MAX) (4)

where TJ(MAX) is the maximum allowable junction temperature (125°C for the LM317-N-MIL), and TA(MAX) is the

maximum ambient temperature that will be encountered in the application.

Using the calculated values for TR(MAX) and PD, the maximum allowable value for the junction-to-ambient thermal

resistance (θJA) can be calculated with Equation 5:

θJA = (TR(MAX) / PD) (5)

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Thermal Considerations (continued)

Figure 38. Power Dissipation Diagram

If the calculated maximum allowable thermal resistance is higher than the actual package rating, then no

additional work is needed. If the calculated maximum allowable thermal resistance is lower than the actual

package rating either the power dissipation (PD) needs to be reduced, the maximum ambient temperature TA(MAX)

needs to be reduced, the thermal resistance (θJA) must be lowered by adding a heatsink, or some combination of

these.

If a heatsink is needed, the value can be calculated from Equation 6:

θHA ≤(θJA – (θCH +θJC))

where

•θCH is the thermal resistance of the contact area between the device case and the heatsink surface

•θJC is thermal resistance from the junction of the die to surface of the package case (6)

When a value for θHA is found using the equation shown, a heatsink must be selected that has a value that is

less than, or equal to, this number.

The θHA rating is specified numerically by the heatsink manufacturer in the catalog, or shown in a curve that plots

temperature rise vs power dissipation for the heatsink.

10.3.2 Heatsinking Surface Mount Packages

The TO-263 (KTT), SOT-223 (DCY) and TO-252 (NDP) 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.

10.3.2.1 Heatsinking the SOT-223 (DCY) Package

Figure 39 and Figure 40 show the information for the SOT-223 package. Figure 40 assumes a θJA of 74°C/W for

1-oz. copper and 59.6°C/W for 2-oz. copper and a maximum junction temperature of 125°C. See AN-1028

(SNVA036) for thermal enhancement techniques to be used with SOT-223 and TO-252 packages.

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Thermal Considerations (continued)

Figure 39. θJA vs Copper (2-oz.) Area for the SOT-223

Package Figure 40. Maximum Power Dissipation vs TAMB for the

SOT-223 Package

10.3.2.2 Heatsinking the TO-263 (KTT) Package

Figure 41 shows for the TO-263 the measured values of θJA for different copper area sizes using a typical PCB

with 1-oz. copper and no solder mask over the copper area used for heatsinking.

As shown in Figure 41, increasing the copper area beyond 1 square inch produces very little improvement. It

must also be observed that the minimum value of θJA for the TO-263 package mounted to a PCB is 32°C/W.

Figure 41. θJA vs Copper (1-oz.) Area for the TO-263 Package

As a design aid, Figure 42 shows the maximum allowable power dissipation compared to ambient temperature

for the TO-263 device (assuming θJA is 35°C/W and the maximum junction temperature is 125°C).

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Thermal Considerations (continued)

Figure 42. Maximum Power Dissipation vs TAMB for the TO-263 Package

10.3.2.3 Heatsinking the TO-252 (NDP) Package

If the maximum allowable value for θJA is found to be ≥54°C/W (typical rated value) for the TO-252 package, no

heatsink is needed because the package alone will dissipate enough heat to satisfy these requirements. If the

calculated value for θJA falls below these limits, a heatsink is required.

As a design aid, Table 1 shows the value of the θJA of NDP the package for different heatsink area. The copper

patterns that we used to measure these θJAs are shown in Figure 47.Figure 43 reflects the same test results as

what are in Table 1.

Figure 44 shows the maximum allowable power dissipation versus ambient temperature for the TO-252 device.

Figure 45 shows the maximum allowable power dissipation versus copper area (in2) for the TO-252 device. See

AN-1028 (SNVA036) for thermal enhancement techniques to be used with SOT-223 and TO-252 packages.

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Thermal Considerations (continued)

(1) Tab of device attached to topside of copper.

Table 1. θJA Different Heatsink Area

LAYOUT COPPER AREA THERMAL RESISTANCE

Top Side (in2)(1) Bottom Side (in2) (θJA°C/W) TO-252

1 0.0123 0 103

2 0.066 0 87

3 0.3 0 60

4 0.53 0 54

5 0.76 0 52

6 1.0 0 47

7 0.066 0.2 84

8 0.066 0.4 70

9 0.066 0.6 63

10 0.066 0.8 57

11 0.066 1.0 57

12 0.066 0.066 89

13 0.175 0.175 72

14 0.284 0.284 61

15 0.392 0.392 55

16 0.5 0.5 53

Figure 43. θJA vs 2-oz. Copper Area for TO-252 Figure 44. Maximum Allowable Power Dissipation vs

Ambient Temperature for TO-252

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Figure 45. Maximum Allowable Power Dissipation vs 2-oz. Copper Area for TO-252

Figure 46. Top View of the Thermal Test Pattern in Actual Scale

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Figure 47. Bottom View of the Thermal Test Pattern in Actual Scale

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11 Device and Documentation Support

11.1 Documentation Support

11.1.1 Related Documentation

• For applications requiring greater output current, see LM150 series (3A) (SNVS772) and LM138 series (5A)

(SNVS771) data sheets.

• For the negative complement, see LM137 (SNVS778) series data sheet.

• For specifications and availability for military and space grades of LM117/883, see the LM117QML data sheet

(SNVS356).

• Specifications and availability for military and space grades of LM117JAN can be found in the LM117 data

sheet (SNVS365).

• For thermal enhancement techniques to be used with SOT-223 and TO-252 packages, see AN-1028,

Maximum Power Enhancement Techniques for Power Packages (SNVA036).

11.2 Related Links

The table below lists quick access links. Categories include technical documents, support and community

resources, tools and software, and quick access to sample or buy.

Table 2. Related Links

PARTS PRODUCT FOLDER SAMPLE & BUY TECHNICAL

DOCUMENTS TOOLS &

SOFTWARE SUPPORT &

COMMUNITY

LM317-N-MIL Click here Click here Click here Click here Click here

11.3 Community Resources

The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective

contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of

Use.

TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration

among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help

solve problems with fellow engineers.

Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and

contact information for technical support.

11.4 Trademarks

E2E is a trademark of Texas Instruments.

All other trademarks are the property of their respective owners.

11.5 Electrostatic Discharge Caution

These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam

during storage or handling to prevent electrostatic damage to the MOS gates.

11.6 Glossary

SLYZ022 —TI Glossary.

This glossary lists and explains terms, acronyms, and definitions.

12 Mechanical, Packaging, and Orderable Information

The following pages include mechanical, packaging, and orderable information. This information is the most

current data available for the designated devices. This data is subject to change without notice and revision of

this document. For browser-based versions of this data sheet, refer to the left-hand navigation.

PACKAGE OPTION ADDENDUM

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PACKAGING INFORMATION

Orderable Device Status

(1)

Package Type Package

Drawing Pins Package

Qty Eco Plan

(2)

Lead finish/

Ball material

(6)

MSL Peak Temp

(3)

Op Temp (°C) Device Marking

(4/5)

Samples

LM317K STEEL ACTIVE TO-3 NDS 2 50 Non-RoHS &

Non-Green Call TI Call TI 0 to 0 LM317K

STEELP+

LM317K STEEL/NOPB ACTIVE TO-3 NDS 2 50 RoHS & Green Call TI Level-1-NA-UNLIM 0 to 0 LM317K

STEELP+

(1) The marketing status values are defined as follows:

ACTIVE: Product device recommended for new designs.

LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.

NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.

PREVIEW: Device has been announced but is not in production. Samples may or may not be available.

OBSOLETE: TI has discontinued the production of the device.

(2) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance

do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may

reference these types of products as "Pb-Free".

RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.

Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of <=1000ppm threshold. Antimony trioxide based

flame retardants must also meet the <=1000ppm threshold requirement.

(3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.

(4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device.

(5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation

of the previous line and the two combined represent the entire Device Marking for that device.

(6) Lead finish/Ball material - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead finish/Ball material values may wrap to two

lines if the finish value exceeds the maximum column width.

Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information

provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and

continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.

TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.

In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.

PACKAGE OPTION ADDENDUM

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MECHANICAL DATA

NDS0002A

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