Pin 1. Input
2. Ground
3. Output
Tab/Case is Ground or Output
13
3
1
TO-3
SOT-223
TO-220
TO-263
2
12
23
12
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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 2000REVISED SEPTEMBER 2016
LM340, LM340A and LM7805 Family Wide V
IN
1.5-A Fixed Voltage Regulators
1
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).
2
LM340
,
LM340A
,
LM7805
,
LM7812
,
LM7815
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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......................... 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
3
LM340
,
LM340A
,
LM7805
,
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,
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
4
LM340
,
LM340A
,
LM7805
,
LM7812
,
LM7815
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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
5
LM340
,
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,
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,
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,
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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 (tw10 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 TJ125°C (LM340A) unless otherwise specified(1)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
VOOutput voltage
TJ= 25°C 4.9 5 5.1 V
PD15 W, 5 mA IO1 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 IO1.5 A 10 25 mV
250 mA IO750 mA 15 mV
Over temperature, 5 mA IO1 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 IO1 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 f100 kHz 40 μV
Ripple rejection
f = 120 Hz
8 V VIN 18
V
TJ= 25°C, , IO= 1 A 68 80 dB
Over temperature, IO= 500 mA 68 dB
RO
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
6
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 (tw10 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 TJ125°C unless otherwise specified(1)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
VOOutput voltage
TJ= 25°C, 5 mA IO1 A 4.8 5 5.2 V
PD15 W, 5 mA IO1 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
IO1 A
TJ= 25°C
7.5V VIN 20V 50 mV
Over temperature
8V VIN 12V 25 mV
ΔVOLoad regulation TJ= 25°C 5 mA IO1.5 A 10 50 mV
250 mA IO750 mA 25 mV
Over temperature, 5 mA IO1 A 50 mV
IQQuiescent current IO1 A TJ= 25°C 8 mA
Over temperature 8.5 mA
ΔIQQuiescent current change
0°C TJ125°C, 5 mA IO1 A 0.5 mA
7 V VIN 20 V TJ= 25°C, IO1 A 1 mA
Over temperature, IO500
mA 1mA
VNOutput noise voltage TA= 25°C, 10 Hz f100 kHz 40 μV
Ripple rejection f = 120 Hz
8 V VIN 18 V
TJ= 25°C, IO1 A 62 80 dB
Over temperature, IO500
mA 62 dB
RO
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, IO1 A 7.5 V
7
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,
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,
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,
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,
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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 (tw10 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 TJ125°C unless otherwise specified(1)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
VOOutput voltage
TJ= 25°C, 5 mA IO1 A 11.5 12 12.5 V
PD15 W, 5 mA IO1 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
IO1 A
TJ= 25°C
14.6V VIN 27V 120 mV
Over temperature
16V VIN 22V 60 mV
ΔVOLoad regulation TJ= 25°C 5 mA IO1.5 A 12 120 mV
250 mA IO750 mA 60 mV
Over temperature, 5 mA IO1 A 120 mV
IQQuiescent current IO1 A TJ= 25°C 8 mA
Over temperature 8.5 mA
ΔIQQuiescent current change
5 mA IO1 A 0.5 mA
TJ= 25°C, IO1 A
14.8 V VIN 27 V 1mA
Over temperature, IO500 mA
14.5 V VIN 30 V 1mA
VNOutput noise voltage TA= 25°C, 10 Hz f100 kHz 75 μV
Ripple rejection f = 120 Hz
15 V VIN 25
V
TJ= 25°C, IO1 A 55 72 dB
Over temperature, IO500
mA, 55 dB
RO
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, IO1 A 14.6 V
8
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 (tw10 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 TJ125°C unless otherwise specified(1)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
VOOutput voltage
TJ= 25°C, 5 mA IO1 A 14.4 15 15.6 V
PD15 W, 5 mA IO1 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
IO1 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 IO1.5 A 12 150 mV
250 mA IO750 mA 75 mV
Over temperature, 5 mA IO1 A, 150 mV
IQQuiescent current IO1 A TJ= 25°C 8 mA
Over temperature 8.5 mA
ΔIQQuiescent current change
5 mA IO1 A 0.5 mA
TJ= 25°C, IO1 A
17.9 V VIN 30 V 1mA
Over temperature, IO500 mA
17.5 V VIN 30 V 1mA
VNOutput noise voltage TA= 25°C, 10 Hz f100 kHz 90 μV
Ripple rejection f = 120 Hz
18.5 V VIN
28.5 V
TJ= 25°C, IO1 A 54 70 dB
Over temperature, IO500
mA, 54 dB
RO
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, IO1 A 17.7 V
9
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,
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,
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,
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,
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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
10
LM340
,
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,
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,
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,
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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
11
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,
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,
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,
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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
12
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,
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,
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,
LM7812
,
LM7815
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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.
13
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,
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,
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,
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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
14
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,
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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
VO
VI
0.1 PF
0.22 PF
OUTPUTINPUT
GND
VO
VI
15
LM340
,
LM340A
,
LM7805
,
LM7812
,
LM7815
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SNOSBT0L FEBRUARY 2000REVISED SEPTEMBER 2016
Product Folder Links: 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
16
LM340
,
LM340A
,
LM7805
,
LM7812
,
LM7815
SNOSBT0L FEBRUARY 2000REVISED SEPTEMBER 2016
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Product Folder Links: LM340 LM340A LM7805 LM7812 LM7815
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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
17
LM340
,
LM340A
,
LM7805
,
LM7812
,
LM7815
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SNOSBT0L FEBRUARY 2000REVISED SEPTEMBER 2016
Product Folder Links: LM340 LM340A LM7805 LM7812 LM7815
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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
18
LM340
,
LM340A
,
LM7805
,
LM7812
,
LM7815
SNOSBT0L FEBRUARY 2000REVISED SEPTEMBER 2016
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Product Folder Links: LM340 LM340A LM7805 LM7812 LM7815
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Layout Example (continued)
Figure 28. Layout Example SOT-223
10.3 Heat Sinking DDPAK/TO-263 and SOT-223 Package Parts
Both the DDPAK/TO-263 (KTT) and SOT-223 (DCY) packages use a copper plane on the PCB and the PCB
itself as a heat sink. To optimize the heat sinking ability of the plane and PCB, solder the tab of the plane.
Figure 29 shows for the DDPAK/TO-263 the measured values of θ(J–A) for different copper area sizes using a
typical