LM340SX-5.0/NOPB - NATIONAL SEMICONDUCTOR

Pin 1. Input

2. Ground

3. Output

Tab/Case is Ground or Output

TO-3

SOT-223

TO-220

TO-263

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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.

LM340

LM340A

LM7805

LM7812

LM7815

SNOSBT0L –FEBRUARY 2000–REVISED SEPTEMBER 2016

LM340, LM340A and LM7805 Family Wide V

1.5-A Fixed Voltage Regulators

1 Features

1• Output Current up to 1.5 A

• Available in Fixed 5-V, 12-V, and 15-V Options

• Output Voltage Tolerances of ±2% at TJ= 25°C

(LM340A)

• Line Regulation of 0.01% / V of at 1-A Load

(LM340A)

• Load Regulation of 0.3% / A (LM340A)

• Internal Thermal Overload, Short-Circuit and SOA

Protection

• Available in Space-Saving SOT-223 Package

• Output Capacitance Not Required for Stability

2 Applications

• Industrial Power Supplies

• SMPS Post Regulation

• HVAC Systems

• AC Inventors

• Test and Measurement Equipment

• Brushed and Brushless DC Motor Drivers

• Solar Energy String Invertors

SPACE

Available Packages

3 Description

The LM340 and LM7805 Family monolithic 3-terminal

positive voltage regulators employ internal current-

limiting, thermal shutdown and safe-area

compensation, making them essentially indestructible.

If adequate heat sinking is provided, they can deliver

over 1.5-A output current. They are intended as fixed

voltage regulators in a wide range of applications

including local (on-card) regulation for elimination of

noise and distribution problems associated with

single-point regulation. In addition to use as fixed

voltage regulators, these devices can be used with

external components to obtain adjustable output

voltages and currents.

Considerable effort was expended to make the entire

series of regulators easy to use and minimize the

number of external components. It is not necessary to

bypass the output, although this does improve

transient response. Input bypassing is needed only if

the regulator is located far from the filter capacitor of

the power supply.

LM7805 is also available in a higher accuracy and

better performance version (LM340A). Refer to

LM340A specifications in the LM340A Electrical

Characterisitcs table.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (NOM)

LM340x

LM7805 Family

DDPAK/TO-263 (3) 10.18 mm × 8.41 mm

SOT-223 (4) 6.50 mm × 3.50 mm

TO-220 (3) 14.986 mm × 10.16 mm

TO-3 (2) 38.94 mm x 25.40 mm

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

the end of the data sheet.

Fixed Output Voltage Regulator

*Required if the regulator is located far from

the power supply filter.

**Although no output capacitor is needed

for stability, it does help transient response.

(If needed, use 0.1-μF, ceramic disc).

LM340

LM340A

LM7805

LM7812

LM7815

SNOSBT0L –FEBRUARY 2000–REVISED SEPTEMBER 2016

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Product Folder Links: LM340 LM340A LM7805 LM7812 LM7815

Table of Contents

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

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

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

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

5 Pin Configuration and Functions......................... 3

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

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

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

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

6.4 Thermal Information.................................................. 4

6.5 LM340A Electrical Characteristics,

VO= 5 V, VI= 10 V............................................................ 5

6.6 LM340 / LM7805 Electrical Characteristics,

VO= 5 V, VI= 10 V............................................................ 6

6.7 LM340 / LM7812 Electrical Characteristics,

VO= 12 V, VI= 19 V.......................................................... 7

6.8 LM340 / LM7815 Electrical Characteristics,

VO= 15 V, VI= 23 V.......................................................... 8

6.9 Typical Characteristics.............................................. 9

7 Detailed Description............................................ 12

7.1 Overview................................................................. 12

7.2 Functional Block Diagram....................................... 12

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

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

8 Application and Implementation ........................ 13

8.1 Application Information............................................ 13

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

8.3 System Examples ................................................... 15

9 Power Supply Recommendations...................... 17

10 Layout................................................................... 17

10.1 Layout Guidelines ................................................. 17

10.2 Layout Example ................................................... 17

10.3 Heat Sinking DDPAK/TO-263 and SOT-223

Package Parts.......................................................... 18

11 Device and Documentation Support................. 20

11.1 Documentation Support ........................................ 20

11.2 Related Links ........................................................ 20

11.3 Receiving Notification of Documentation Updates 20

11.4 Community Resources.......................................... 20

11.5 Trademarks........................................................... 20

11.6 Electrostatic Discharge Caution............................ 20

11.7 Glossary................................................................ 20

12 Mechanical, Packaging, and Orderable

Information........................................................... 21

4 Revision History

NOTE: Page numbers for previous revisions may differ from page numbers in the current version.

Changes from Revision K (November 2015) to Revision L Page

• Changed pinout number order for the TO-220 and SOT-223 packages from: 2, 3, 1 to: 1, 2, 3 .......................................... 1

Changes from Revision J (December 2013) to Revision K Page

• Added ESD Ratings table, Thermal Information table, Feature Description section, Device Functional Modes,

Application and Implementation section, Power Supply Recommendations section, Layout section, Device and

Documentation Support section, and Mechanical, Packaging, and Orderable Information section....................................... 1

• Deleted obsolete LM140 and LM7808C devices from the data sheet ................................................................................... 1

• Changed Figure 13 caption from Line Regulation 140AK-5.0 to Line Regulation LM340, .................................................. 11

• Changed Figure 14 caption from Line Regulation 140AK-5.0 to Line Regulation LM340, .................................................. 11

Changes from Revision I (March 2013) to Revision J Page

• Changed 0.5 from typ to max................................................................................................................................................. 5

LM340

LM340A

LM7805

LM7812

LM7815

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5 Pin Configuration and Functions

LM7805 and LM7812 KTT Package

3-Pin DDPAK/TO-263

Top View

LM7805, LM7812, and LM7815 NDE Package

3-Pin TO-220

Top View

LM7805 DCY Package

4-Pin SOT-223

Side View

LM340K-5.0 NDS Package

2-Pin TO-3

Top View

Pin Functions

PIN I/O DESCRIPTION

NAME NO.

INPUT 1 I Input voltage pin

GND 2 I/O Ground pin

OUTPUT 3 O Output voltage pin

LM340

LM340A

LM7805

LM7812

LM7815

SNOSBT0L –FEBRUARY 2000–REVISED SEPTEMBER 2016

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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.

(3) The maximum allowable power dissipation at any ambient temperature is a function of the maximum junction temperature for operation

(TJMAX = 125°C or 150°C), the junction-to-ambient thermal resistance (θJA), and the ambient temperature (TA). PDMAX = (TJMAX −

TA)/θJA. If this dissipation is exceeded, the die temperature rises above TJMAX and the electrical specifications do not apply. If the die

temperature rises above 150°C, the device goes into thermal shutdown. For the TO-3 package (NDS), the junction-to-ambient thermal

resistance (θJA) is 39°C/W. When using a heat sink, θJA is the sum of the 4°C/W junction-to-case thermal resistance (θJC) of the TO-3

package and the case-to-ambient thermal resistance of the heat sink. For the TO-220 package (NDE), θJA is 54°C/W and θJC is 4°C/W.

If SOT-223 is used, the junction-to-ambient thermal resistance is 174°C/W and can be reduced by a heat sink (see Applications Hints on

heat sinking).If the DDPAK\TO-263 package is used, the thermal resistance can be reduced by increasing the PCB copper area

thermally connected to the package: Using 0.5 square inches of copper area, θJA is 50°C/W; with 1 square inch of copper area, θJA is

37°C/W; and with 1.6 or more inches of copper area, θJA is 32°C/W.

6 Specifications

6.1 Absolute Maximum Ratings

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

MIN MAX UNIT

DC input voltage 35 V

Internal power dissipation(3) Internally Limited

Maximum junction temperature 150 °C

Lead temperature (soldering, 10 sec.) TO-3 package (NDS) 300 °C

Lead temperature 1,6 mm (1/16 in) from case for 10 s 230 °C

Storage temperature −65 150 °C

(1) ESD rating is based on the human-body model, 100 pF discharged through 1.5 kΩ.

6.2 ESD Ratings VALUE UNIT

V(ESD) Electrostatic

discharge Human-body model (HBM)(1) ±2000 V

6.3 Recommended Operating Conditions

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

Temperature (TA) LM340A, LM340 0 125 °C

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

report.

6.4 Thermal Information

THERMAL METRIC(1)

LM340, LM7805 Family

UNIT

NDE

(TO-220) KTT

(DDPAK/TO-263) DCY

(SOT-223) NDS

(TO-3)

3 PINS 3 PINS 4 PINS 2 PINS

RθJA Junction-to-ambient thermal resistance 23.9 44.8 62.1 39 °C/W

RθJC(top) Junction-to-case (top) thermal resistance 16.7 45.6 44 2 °C/W

RθJB Junction-to-board thermal resistance 5.3 24.4 10.7 — °C/W

ψJT Junction-to-top characterization parameter 3.2 11.2 2.7 — °C/W

ψJB Junction-to-board characterization parameter 5.3 23.4 10.6 — °C/W

RθJC(bot) Junction-to-case (bottom) thermal resistance 1.7 1.5 — — °C/W

LM340

LM340A

LM7805

LM7812

LM7815

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(1) All characteristics are measured with a 0.22-μF capacitor from input to ground and a 0.1-μF capacitor from output to ground. All

characteristics except noise voltage and ripple rejection ratio are measured using pulse techniques (tw≤10 ms, duty cycle ≤5%).

Output voltage changes due to changes in internal temperature must be taken into account separately.

6.5 LM340A Electrical Characteristics,

VO= 5 V, VI= 10 V

IOUT = 1 A, 0°C ≤TJ≤125°C (LM340A) unless otherwise specified(1)

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

VOOutput voltage

TJ= 25°C 4.9 5 5.1 V

PD≤15 W, 5 mA ≤IO≤1 A

7.5 V ≤VIN ≤20 V 4.8 5.2 V

ΔVOLine regulation

7.5 V ≤VIN ≤20

VTJ= 25°C 3 10 mV

Over temperature, IO= 500 mA 10 mV

8 V ≤VIN ≤12 V TJ= 25°C 4 mV

Over temperature 12 mV

ΔVOLoad regulation TJ= 25°C 5 mA ≤IO≤1.5 A 10 25 mV

250 mA ≤IO≤750 mA 15 mV

Over temperature, 5 mA ≤IO≤1 A 25 mV

IQQuiescent current TJ= 25°C 6 mA

Over temperature 6.5 mA

ΔIQQuiescent current

change

TJ= 25°C, IO= 1 A

7.5 V ≤VIN ≤20 V 0.8 mA

Over temperature, 5 mA ≤IO≤1 A 0.5 mA

Over temperature, IO= 500 mA

8 V ≤VIN ≤25 V 0.8 mA

VNOutput noise voltage TA= 25°C, 10 Hz ≤f≤100 kHz 40 μV

Ripple rejection

f = 120 Hz

8 V ≤VIN ≤18

TJ= 25°C, , IO= 1 A 68 80 dB

Over temperature, IO= 500 mA 68 dB

Dropout voltage TJ= 25°C, IO= 1 A 2 V

Output resistance f = 1 kHz 8 mΩ

Short-circuit current TJ= 25°C 2.1 A

Peak output current TJ= 25°C 2.4 A

Average TC of VOMin, TJ= 0°C, IO= 5 mA −0.6 mV/°C

VIN Input voltage required to

maintain line regulation TJ= 25°C 7.5 V

LM340

LM340A

LM7805

LM7812

LM7815

SNOSBT0L –FEBRUARY 2000–REVISED SEPTEMBER 2016

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Product Folder Links: LM340 LM340A LM7805 LM7812 LM7815

(1) All characteristics are measured with a 0.22-μF capacitor from input to ground and a 0.1-μF capacitor from output to ground. All

characteristics except noise voltage and ripple rejection ratio are measured using pulse techniques (tw≤10 ms, duty cycle ≤5%).

Output voltage changes due to changes in internal temperature must be taken into account separately.

6.6 LM340 / LM7805 Electrical Characteristics,

VO= 5 V, VI= 10 V

0°C ≤TJ≤125°C unless otherwise specified(1)

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

VOOutput voltage

TJ= 25°C, 5 mA ≤IO≤1 A 4.8 5 5.2 V

PD≤15 W, 5 mA ≤IO≤1 A

7.5 V ≤VIN ≤20 V 4.75 5.25 V

ΔVOLine regulation

IO= 500 mA

TJ= 25°C

7V ≤VIN ≤25V 3 50 mV

Over temperature

8V ≤VIN ≤20V 50 mV

IO≤1 A

TJ= 25°C

7.5V ≤VIN ≤20V 50 mV

Over temperature

8V ≤VIN ≤12V 25 mV

ΔVOLoad regulation TJ= 25°C 5 mA ≤IO≤1.5 A 10 50 mV

250 mA ≤IO≤750 mA 25 mV

Over temperature, 5 mA ≤IO≤1 A 50 mV

IQQuiescent current IO≤1 A TJ= 25°C 8 mA

Over temperature 8.5 mA

ΔIQQuiescent current change

0°C ≤TJ≤125°C, 5 mA ≤IO≤1 A 0.5 mA

7 V ≤VIN ≤20 V TJ= 25°C, IO≤1 A 1 mA

Over temperature, IO≤500

mA 1mA

VNOutput noise voltage TA= 25°C, 10 Hz ≤f≤100 kHz 40 μV

Ripple rejection f = 120 Hz

8 V ≤VIN ≤18 V

TJ= 25°C, IO≤1 A 62 80 dB

Over temperature, IO≤500

mA 62 dB

Dropout voltage TJ= 25°C, IO= 1 A 2 V

Output resistance f = 1 kHz 8 mΩ

Short-circuit current TJ= 25°C 2.1 A

Peak output current TJ= 25°C 2.4 A

Average TC of VOUT Over temperature, IO= 5 mA −0.6 mV/°C

VIN Input voltage required to

maintain line regulation TJ= 25°C, IO≤1 A 7.5 V

LM340

LM340A

LM7805

LM7812

LM7815

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(1) All characteristics are measured with a 0.22-μF capacitor from input to ground and a 0.1-μF capacitor from output to ground. All

characteristics except noise voltage and ripple rejection ratio are measured using pulse techniques (tw≤10 ms, duty cycle ≤5%).

Output voltage changes due to changes in internal temperature must be taken into account separately.

6.7 LM340 / LM7812 Electrical Characteristics,

VO= 12 V, VI= 19 V

0°C ≤TJ≤125°C unless otherwise specified(1)

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

VOOutput voltage

TJ= 25°C, 5 mA ≤IO≤1 A 11.5 12 12.5 V

PD≤15 W, 5 mA ≤IO≤1 A

14.5 V ≤VIN ≤27 V 11.4 12.6 V

ΔVOLine regulation

IO= 500 mA

TJ= 25°C

14.5V ≤VIN ≤30V 4 120 mV

Over temperature

15V ≤VIN ≤27V 120 mV

IO≤1 A

TJ= 25°C

14.6V ≤VIN ≤27V 120 mV

Over temperature

16V ≤VIN ≤22V 60 mV

ΔVOLoad regulation TJ= 25°C 5 mA ≤IO≤1.5 A 12 120 mV

250 mA ≤IO≤750 mA 60 mV

Over temperature, 5 mA ≤IO≤1 A 120 mV

IQQuiescent current IO≤1 A TJ= 25°C 8 mA

Over temperature 8.5 mA

ΔIQQuiescent current change

5 mA ≤IO≤1 A 0.5 mA

TJ= 25°C, IO≤1 A

14.8 V ≤VIN ≤27 V 1mA

Over temperature, IO≤500 mA

14.5 V ≤VIN ≤30 V 1mA

VNOutput noise voltage TA= 25°C, 10 Hz ≤f≤100 kHz 75 μV

Ripple rejection f = 120 Hz

15 V ≤VIN ≤25

TJ= 25°C, IO≤1 A 55 72 dB

Over temperature, IO≤500

mA, 55 dB

Dropout voltage TJ= 25°C, IO= 1 A 2 V

Output resistance f = 1 kHz 18 mΩ

Short-circuit current TJ= 25°C 1.5 A

Peak output current TJ= 25°C 2.4 A

Average TC of VOUT Over temperature, IO= 5 mA −1.5 mV/°C

VIN Input voltage required to

maintain line regulation TJ= 25°C, IO≤1 A 14.6 V

LM340

LM340A

LM7805

LM7812

LM7815

SNOSBT0L –FEBRUARY 2000–REVISED SEPTEMBER 2016

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Product Folder Links: LM340 LM340A LM7805 LM7812 LM7815

(1) All characteristics are measured with a 0.22-μF capacitor from input to ground and a 0.1-μF capacitor from output to ground. All

characteristics except noise voltage and ripple rejection ratio are measured using pulse techniques (tw≤10 ms, duty cycle ≤5%).

Output voltage changes due to changes in internal temperature must be taken into account separately.

6.8 LM340 / LM7815 Electrical Characteristics,

VO= 15 V, VI= 23 V

0°C ≤TJ≤125°C unless otherwise specified(1)

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

VOOutput voltage

TJ= 25°C, 5 mA ≤IO≤1 A 14.4 15 15.6 V

PD≤15 W, 5 mA ≤IO≤1 A

17.5 V ≤VIN ≤30 V 14.25 15.75 V

ΔVOLine regulation

IO= 500 mA

TJ= 25°C

17.5 V ≤VIN ≤30 V 4 150 mV

Over temperature

18.5 V ≤VIN ≤30 V 150 mV

IO≤1 A

TJ= 25°C

17.7 V ≤VIN ≤30 V 150 mV

Over temperature

20 V ≤VIN ≤26 V 75 mV

ΔVOLoad regulation TJ= 25°C 5 mA ≤IO≤1.5 A 12 150 mV

250 mA ≤IO≤750 mA 75 mV

Over temperature, 5 mA ≤IO≤1 A, 150 mV

IQQuiescent current IO≤1 A TJ= 25°C 8 mA

Over temperature 8.5 mA

ΔIQQuiescent current change

5 mA ≤IO≤1 A 0.5 mA

TJ= 25°C, IO≤1 A

17.9 V ≤VIN ≤30 V 1mA

Over temperature, IO≤500 mA

17.5 V ≤VIN ≤30 V 1mA

VNOutput noise voltage TA= 25°C, 10 Hz ≤f≤100 kHz 90 μV

Ripple rejection f = 120 Hz

18.5 V ≤VIN ≤

28.5 V

TJ= 25°C, IO≤1 A 54 70 dB

Over temperature, IO≤500

mA, 54 dB

Dropout voltage TJ= 25°C, IO= 1 A 2 V

Output resistance f = 1 kHz 19 mΩ

Short-circuit current TJ= 25°C 1.2 A

Peak output current TJ= 25°C 2.4 A

Average TC of VOUT Over temperature, IO= 5 mA −1.8 mV/°C

VIN Input voltage required to

maintain line regulation TJ= 25°C, IO≤1 A 17.7 V

LM340

LM340A

LM7805

LM7812

LM7815

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6.9 Typical Characteristics

Figure 1. Maximum Average Power Dissipation Figure 2. Maximum Average Power Dissipation

Figure 3. Maximum Power Dissipation (DDPAK/TO-263)

Shaded area refers to LM340A/LM340, LM7805, LM7812 and

LM7815.

Figure 4. Output Voltage (Normalized to 1 V at TJ= 25°C)

Figure 5. Ripple Rejection Figure 6. Ripple Rejection

LM340

LM340A

LM7805

LM7812

LM7815

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Typical Characteristics (continued)

Figure 7. Output Impedance Figure 8. Dropout Characteristics

Shaded area refers to LM340A/LM340, LM7805, LM7812, and

LM7815. Figure 9. Quiescent Current Figure 10. Peak Output Current

Shaded area refers to LM340A/LM340, LM7805, LM7812, and

LM7815. Figure 11. Dropout Voltage Figure 12. Quiescent Current

LM340

LM340A

LM7805

LM7812

LM7815

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Typical Characteristics (continued)

IOUT = 1 A, TA= 25°C

Figure 13. Line Regulation LM340 VIN = 10 V, TA= 25°C

Figure 14. Line Regulation LM340

LM340

LM340A

LM7805

LM7812

LM7815

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Product Folder Links: LM340 LM340A LM7805 LM7812 LM7815

7 Detailed Description

7.1 Overview

The LM340 and LM7805 devices are a family of fixed output positive voltage regulators with outputs ranging from

3 V to 15 V. They accept up to 35 V of input voltage and with proper heat dissipation can provide over 1.5 A of

current. With a combination of current limiting, thermal shutdown, and safe area protection, these regulators

eliminate any concern of damage. These features paired with excellent line and load regulation make the LM340

and LM7805 Family versatile solutions to a wide range of power management designs. Although the LM340 and

LM7805 Family were designed primarily as fixed-voltage regulators, these devices can be used with external

component for adjustable voltage and current.

7.2 Functional Block Diagram

7.3 Feature Description

7.3.1 Output Current

With proper considerations, the LM340 and LM7805 Family can exceed 1.5-A output current. Depending on the

desired package option, the effective junction-to-ambient thermal resistance can be reduced through heat

sinking, allowing more power to be dissipated in the device.

7.3.2 Current Limiting Feature

In the event of a short circuit at the output of the regulator, each device has an internal current limit to protect it

from damage. The typical current limits for the LM340 and LM7805 Family is 2.4 A.

7.3.3 Thermal Shutdown

Each package type employs internal current limiting and thermal shutdown to provide safe operation area

protection. If the junction temperature is allowed to rise to 150°C, the device will go into thermal shutdown.

7.4 Device Functional Modes

There are no functional modes for this device.

LM340

LM340A

LM7805

LM7812

LM7815

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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 should

validate and test their design implementation to confirm system functionality.

8.1 Application Information

The LM340x and LM7805 series is designed with thermal protection, output short-circuit protection, and output

transistor safe area protection. However, as with any IC regulator, it becomes necessary to take precautions to

assure that the regulator is not inadvertently damaged. The following describes possible misapplications and

methods to prevent damage to the regulator.

8.1.1 Shorting the Regulator Input

When using large capacitors at the output of these regulators, a protection diode connected input to output

(Figure 15) may be required if the input is shorted to ground. Without the protection diode, an input short causes

the input to rapidly approach ground potential, while the output remains near the initial VOUT because of the

stored charge in the large output capacitor. The capacitor will then discharge through a large internal input to

output diode and parasitic transistors. If the energy released by the capacitor is large enough, this diode, low

current metal, and the regulator are destroyed. The fast diode in Figure 15 shunts most of the capacitors

discharge current around the regulator. Generally no protection diode is required for values of output capacitance

≤10 μF.

8.1.2 Raising the Output Voltage Above the Input Voltage

Because the output of the device does not sink current, forcing the output high can cause damage to internal low

current paths in a manner similar to that just described in Shorting the Regulator Input.

8.1.3 Regulator Floating Ground

When the ground pin alone becomes disconnected, the output approaches the unregulated input, causing

possible damage to other circuits connected to VOUT. If ground is reconnected with power ON, damage may also

occur to the regulator. This fault is most likely to occur when plugging in regulators or modules with on card

regulators into powered up sockets. The power must be turned off first, the thermal limit ceases operating, or the

ground must be connected first if power must be left on. See Figure 16.

8.1.4 Transient Voltages

If transients exceed the maximum rated input voltage of the device, or reach more than 0.8 V below ground and

have sufficient energy, they will damage the regulator. The solution is to use a large input capacitor, a series

input breakdown diode, a choke, a transient suppressor or a combination of these.

Figure 15. Input Short

LM340

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Application Information (continued)

Figure 16. Regulator Floating Ground

Figure 17. Transients

When a value for θ(H–A) is found, a heat sink must be selected that has a value that is less than or equal to this

number.

θ(H–A) is specified numerically by the heat sink manufacturer in this catalog or shown in a curve that plots

temperature rise vs power dissipation for the heat sink.

8.2 Typical Applications

8.2.1 Fixed Output Voltage Regulator

The LM340x and LM7805 Family devices are primarily designed to provide fixed output voltage regulation. The

simplest implementation of LM340x and LM7805 Family is shown in Figure 18.

*Required if the regulator is located far from the power supply filter.

**Although no output capacitor is needed for stability, it does help transient response. (If needed, use 0.1-μF, ceramic

disc).

Figure 18. Fixed Output Voltage Regulator

8.2.1.1 Design Requirements

The device component count is very minimal. Although not required, TI recommends employing bypass

capacitors at the output for optimum stability and transient response. These capacitors must be placed as close

as possible to the regulator. If the device is located more than 6 inches from the power supply filter, it is required

to employ input capacitor.

0.1 PF

0.22 PF

OUTPUTINPUT

GND

0.1 PF

0.22 PF

OUTPUTINPUT

GND

LM340

LM340A

LM7805

LM7812

LM7815

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Typical Applications (continued)

8.2.1.2 Detailed Design Procedure

The output voltage is set based on the device variant. LM340x and LM7805 Family are available in 5-V, 12-V

and 15-V regulator options.

8.2.1.3 Application Curve

Figure 19. VOUT vs VIN, VOUT =5V

8.3 System Examples

IOUT = V2–3 / R1 + IQ

ΔIQ= 1.3 mA over line and load changes. VOUT = 5 V + (5 V/R1 + IQ) R2 5 V/R1 > 3 IQ,

load regulation (Lr)≈[(R1 + R2)/R1] (Lrof LM340-5).

Figure 20. Current Regulator Figure 21. Adjustable Output Regulator

Figure 22. High Input Voltage Circuit With Series

Resistor Figure 23. High Input Voltage Circuit

implementation With Transistor

0.1 PF

OUTPUTINPUT

GND

+ OUT

+ +

0.1 PF

OUTPUTINPUT

GND

- OUT

+ +

LM340

LM79xx

0.1 PF

0.22 PF

OUTPUT

INPUT

GND

3.0:

2N6133

IO MAX

IQ1

IREG

0.1 PF

0.22 PF

OUTPUT

INPUT

GND

OUT

3.0:

2N6132

RSC

2N6124

LM340

LM340A

LM7805

LM7812

LM7815

SNOSBT0L –FEBRUARY 2000–REVISED SEPTEMBER 2016

www.ti.com

Product Folder Links: LM340 LM340A LM7805 LM7812 LM7815

System Examples (continued)

β(Q1) ≥IO Max / IREG Max

R1 = 0.9 / IREG =β(Q1) VBE(Q1) / IREG Max (β+1) – IO Max

RSC = 0.8 / ISC

R1 = βVBE(Q1) / IREG Max (β+1) – IO Max

Figure 24. High Current Voltage Regulator Figure 25. High Output Current With Short-Circuit

Protection

Figure 26. LM340 Used With Negative Regulator LM79xx

LM340

LM340A

LM7805

LM7812

LM7815

www.ti.com

SNOSBT0L –FEBRUARY 2000–REVISED SEPTEMBER 2016

Product Folder Links: LM340 LM340A LM7805 LM7812 LM7815

9 Power Supply Recommendations

The LM340 is designed to operate from a wide input voltage up to 35 V. Please refer to electrical characteristics

tables for the minimum input voltage required for line/load regulation. If the device is more than six inches from

the input filter capacitors, an input bypass capacitor, 0.1 μF or greater, of any type is needed for stability.

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. To improve

PSRR, a bypass capacitor can be placed at the OUTPUT pin and must be placed as close as possible to the IC.

All that is required for the typical fixed output regulator application circuit is the LM340x/LM7805 Family IC and a

0.22-µF input capacitor if the regulator is placed far from the power supply filter. A 0.1-µF output capacitor is

recommended to help with transient response. 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.

10.2 Layout Example

Figure 27. Layout Example DDPAK