LM123,LM323,LM323A
LM123/LM323A/LM323 3-Amp, 5-Volt Positive Regulator
Literature Number: SNVS757B
LM123/LM323A/LM323
3-Amp, 5-Volt Positive Regulator
General Description
The LM123 is a three-terminal positive regulator with a pre-
set 5V output and a load driving capability of 3 amps. New
circuit design and processing techniques are used to provide
the high output current without sacrificing the regulation
characteristics of lower current devices.
The LM323A offers improved precision over the standard
LM323. Parameters with tightened specifications include
output voltage tolerance, line regulation, and load regulation.
The 3 amp regulator is virtually blowout proof. Current limit-
ing, power limiting, and thermal shutdown provide the same
high level of reliability obtained with these techniques in the
LM109 1 amp regulator.
No external components are required for operation of the
LM123. If the device is more than 4 inches from the filter
capacitor, however,a1µFsolid tantalum capacitor should
be used on the input. A 0.1 µF or larger capacitor may be
used on the output to reduce load transient spikes created
by fast switching digital logic, or to swamp out stray load
capacitance.
An overall worst case specification for the combined effects
of input voltage, load currents, ambient temperature, and
power dissipation ensure that the LM123 will perform satis-
factorily as a system element.
For applications requiring other voltages, see LM150 series
adjustable regulator data sheet.
Operation is guaranteed over the junction temperature range
−55˚C to +150˚C for LM123, −40˚C to +125˚C for LM323A,
and 0˚C to +125˚C for LM323. A hermetic TO-3 package is
used for high reliability and low thermal resistance.
Features
nGuaranteed 1% initial accuracy (A version)
n3 amp output current
nInternal current and thermal limiting
n0.01Ωtypical output impedance
n7.5V minimum input voltage
n30W power dissipation
nP
+
Product Enhancement tested
Connection Diagram
Metal Can Package
00777102
Order Number LM123K STEEL, LM323AK STEEL or LM323K STEEL
See NS Package Number K02A
Order Number LM123K/883
See NS Package Number K02C
May 1998
LM123/LM323A/LM323 3-Amp, 5-Volt Positive Regulator
© 2004 National Semiconductor Corporation DS007771 www.national.com
Typical Applications
Basic 3 Amp Regulator
00777103
*Required if LM123 is more than 4" from filter capacitor.
†Regulator is stable with no load capacitor into resistive loads.
LM123/LM323A/LM323
www.national.com 2
Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
(Note 5)
Input Voltage 20V
Power Dissipation Internally Limited
Operating Junction Temperature Range
LM123 −55˚C to +150˚C
LM323A −40˚C to +125˚C
LM323 0˚C to +125˚C
Storage Temperature Range −65˚C to +150˚C
Lead Temperature (Soldering, 10 sec.) 300˚C
ESD Tolerance (Note 5) 2000V
LM123 Electrical Characteristics (Note 2)
Parameter Conditions LM123 Units
Min Typ Max
Output Voltage T
j
= 25˚C 4.7 5 5.3 V
V
IN
= 7.5V, I
OUT
=0A
7.5V ≤V
IN
≤15V 4.6 5.4 V
0A ≤I
OUT
≤3A, P ≤30W
Line Regulation (Note 4) T
j
= 25˚C 5 25 mV
7.5V ≤V
IN
≤15V
Load Regulation (Note 4) T
j
= 25˚C, V
IN
= 7.5V, 25 100 mV
0A ≤I
OUT
≤3A
Quiescent Current 7.5V ≤V
IN
≤15V, 12 20 mA
0A ≤I
OUT
≤3A
Output Noise Voltage T
j
= 25˚C 40 µVrms
10 Hz ≤f≤100 kHz
Short Circuit Current Limit T
j
= 25˚C
V
IN
= 15V 3 4.5 A
V
IN
= 7.5V 4 5 A
Long Term Stability 35 mV
Thermal Resistance Junction
to Case (Note 3) 2 ˚C/W
LM323A/LM323 Electrical Characteristics (Note 2)
Parameter Conditions LM323A LM323 Units
Min Typ Max Min Typ Max
Output Voltage T
j
= 25˚C 4.95 5 5.05 4.8 5 5.2 V
V
IN
= 7.5V, I
OUT
=0A
7.5V ≤V
IN
≤15V 4.85 5.15 4.75 5.25 V
0A ≤I
OUT
≤3A, P ≤30W
Line Regulation (Note 4) T
j
= 25˚C 5 10 5 25 mV
7.5V ≤V
IN
≤15V
Load Regulation (Note 4) T
j
= 25˚C, V
IN
= 7.5V, 25 50 25 100 mV
0A ≤I
OUT
≤3A
Quiescent Current 7.5V ≤V
IN
≤15V, 12 20 12 20 mA
0A ≤I
OUT
≤3A
Output Noise Voltage T
j
= 25˚C 40 40 µVrms
10 Hz ≤f≤100 kHz
Short Circuit Current Limit T
j
= 25˚C
V
IN
= 15V 3 4.5 3 4.5 A
V
IN
= 7.5V 4 6 4 5 A
Long Term Stability 35 35 mV
LM123/LM323A/LM323
www.national.com3
LM323A/LM323 Electrical Characteristics (Note 2) (Continued)
Parameter Conditions LM323A LM323 Units
Min Typ Max Min Typ Max
Thermal Resistance Junction
to Case (Note 3) 2 2 ˚C/W
Note 1: “Absolute Maximum Ratings” indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is
functional, but do not guarantee specific performance limits.
Note 2: Unless otherwise noted, specifications apply for −55˚C ≤Tj≤+150˚C for the LM123, −40˚C ≤Tj≤+125˚C for the LM323A, and 0˚C ≤Tj≤+125˚C for the
LM323. Although power dissipation is internally limited, specifications apply only for P ≤30W.
Note 3: Without a heat sink, the thermal resistance of the TO-3 package is about 35˚C/W. With a heat sink, the effective thermal resistance can only approach the
specified values of 2˚C/W, depending on the efficiency of the heat sink.
Note 4: Load and line regulation are specified at constant junction temperature. Pulse testing is required with a pulse width ≤1 ms and a duty cycle ≤5%.
Note 5: Refer to RETS123K drawing for LM123K military specifications.
Note 6: Human body model, 1.5 kΩin series with 100 pF.
Typical Performance Characteristics
Maximum Average Power
Dissipation for LM123
Maximum Average Power
Dissipation for LM323A, LM323
00777109 00777110
Output Impedance Peak Available Output Current
00777111 00777112
LM123/LM323A/LM323
www.national.com 4
Typical Performance Characteristics (Continued)
Short Circuit Current Ripple Rejection
00777113 00777114
Dropout Voltage Line Transient Response
00777115 00777116
Output Voltage Quiescent Current
00777117 00777118
LM123/LM323A/LM323
www.national.com5
Typical Performance Characteristics (Continued)
Load Transient Response Output Noise Voltage
00777119 00777120
Typical Applications
10 Amp Regulator with Complete Overload Protection
00777106
*Select for 20 mA Current from Unregulated Negative Supply
LM123/LM323A/LM323
www.national.com 6
Typical Applications (Continued)
Adjustable Regulator 0V−10V @3A
00777107
A1— LM101A
C1— 2 µF Optional — Improves Ripple Rejection, Noise, and Transient Response
Trimming Output to 5V
00777108
LM123/LM323A/LM323
www.national.com7
Typical Applications (Continued)
Adjustable Output 5V−10V 0.1% Regulation
00777104
*Select to Set Output Voltage
**Select to Draw 25 mA from V−
Schematic Diagram
00777101
LM123/LM323A/LM323
www.national.com 8
Physical Dimensions inches (millimeters)
unless otherwise noted
Metal Can Package (K)
Order Number LM123K STEEL, LM323AK STEEL or LM323K STEEL
NS Package Number K02A
LM123/LM323A/LM323
www.national.com9
Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
Metal Can Package (K)
Mil-Aero Product
Order Number LM123K/883
NS Package Number K02C
National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves
the right at any time without notice to change said circuitry and specifications.
For the most current product information visit us at www.national.com.
LIFE SUPPORT POLICY
NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS
WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR
CORPORATION. As used herein:
1. Life support devices or systems are devices or systems
which, (a) are intended for surgical implant into the body, or
(b) support or sustain life, and whose failure to perform when
properly used in accordance with instructions for use
provided in the labeling, can be reasonably expected to result
in a significant injury to the user.
2. A critical component is any component of a life support
device or system whose failure to perform can be reasonably
expected to cause the failure of the life support device or
system, or to affect its safety or effectiveness.
BANNED SUBSTANCE COMPLIANCE
National Semiconductor certifies that the products and packing materials meet the provisions of the Customer Products Stewardship
Specification (CSP-9-111C2) and the Banned Substances and Materials of Interest Specification (CSP-9-111S2) and contain no ‘‘Banned
Substances’’ as defined in CSP-9-111S2.
National Semiconductor
Americas Customer
Support Center
Email: new.feedback@nsc.com
Tel: 1-800-272-9959
National Semiconductor
Europe Customer Support Center
Fax: +49 (0) 180-530 85 86
Email: europe.support@nsc.com
Deutsch Tel: +49 (0) 69 9508 6208
English Tel: +44 (0) 870 24 0 2171
Français Tel: +33 (0) 1 41 91 8790
National Semiconductor
Asia Pacific Customer
Support Center
Email: ap.support@nsc.com
National Semiconductor
Japan Customer Support Center
Fax: 81-3-5639-7507
Email: jpn.feedback@nsc.com
Tel: 81-3-5639-7560
www.national.com
LM123/LM323A/LM323 3-Amp, 5-Volt Positive Regulator
IMPORTANT NOTICE
Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements,
and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should
obtain the latest relevant information before placing orders and should verify that such information is current and complete. All products are
sold subject to TI’s terms and conditions of sale supplied at the time of order acknowledgment.
TI warrants performance of its hardware products to the specifications applicable at the time of sale in accordance with TI’s standard
warranty. Testing and other quality control techniques are used to the extent TI deems necessary to support this warranty. Except where
mandated by government requirements, testing of all parameters of each product is not necessarily performed.
TI assumes no liability for applications assistance or customer product design. Customers are responsible for their products and
applications using TI components. To minimize the risks associated with customer products and applications, customers should provide
adequate design and operating safeguards.
TI does not warrant or represent that any license, either express or implied, is granted under any TI patent right, copyright, mask work right,
or other TI intellectual property right relating to any combination, machine, or process in which TI products or services are used. Information
published by TI regarding third-party products or services does not constitute a license from TI to use such products or services or a
warranty or endorsement thereof. Use of such information may require a license from a third party under the patents or other intellectual
property of the third party, or a license from TI under the patents or other intellectual property of TI.
Reproduction of TI information in TI data books or data sheets is permissible only if reproduction is without alteration and is accompanied
by all associated warranties, conditions, limitations, and notices. Reproduction of this information with alteration is an unfair and deceptive
business practice. TI is not responsible or liable for such altered documentation. Information of third parties may be subject to additional
restrictions.
Resale of TI products or services with statements different from or beyond the parameters stated by TI for that product or service voids all
express and any implied warranties for the associated TI product or service and is an unfair and deceptive business practice. TI is not
responsible or liable for any such statements.
TI products are not authorized for use in safety-critical applications (such as life support) where a failure of the TI product would reasonably
be expected to cause severe personal injury or death, unless officers of the parties have executed an agreement specifically governing
such use. Buyers represent that they have all necessary expertise in the safety and regulatory ramifications of their applications, and
acknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements concerning their products
and any use of TI products in such safety-critical applications, notwithstanding any applications-related information or support that may be
provided by TI. Further, Buyers must fully indemnify TI and its representatives against any damages arising out of the use of TI products in
such safety-critical applications.
TI products are neither designed nor intended for use in military/aerospace applications or environments unless the TI products are
specifically designated by TI as military-grade or "enhanced plastic."Only products designated by TI as military-grade meet military
specifications. Buyers acknowledge and agree that any such use of TI products which TI has not designated as military-grade is solely at
the Buyer's risk, and that they are solely responsible for compliance with all legal and regulatory requirements in connection with such use.
TI products are neither designed nor intended for use in automotive applications or environments unless the specific TI products are
designated by TI as compliant with ISO/TS 16949 requirements. Buyers acknowledge and agree that, if they use any non-designated
products in automotive applications, TI will not be responsible for any failure to meet such requirements.
Following are URLs where you can obtain information on other Texas Instruments products and application solutions:
Products Applications
Audio www.ti.com/audio Communications and Telecom www.ti.com/communications
Amplifiers amplifier.ti.com Computers and Peripherals www.ti.com/computers
Data Converters dataconverter.ti.com Consumer Electronics www.ti.com/consumer-apps
DLP®Products www.dlp.com Energy and Lighting www.ti.com/energy
DSP dsp.ti.com Industrial www.ti.com/industrial
Clocks and Timers www.ti.com/clocks Medical www.ti.com/medical
Interface interface.ti.com Security www.ti.com/security
Logic logic.ti.com Space, Avionics and Defense www.ti.com/space-avionics-defense
Power Mgmt power.ti.com Transportation and Automotive www.ti.com/automotive
Microcontrollers microcontroller.ti.com Video and Imaging www.ti.com/video
RFID www.ti-rfid.com
OMAP Mobile Processors www.ti.com/omap
Wireless Connectivity www.ti.com/wirelessconnectivity
TI E2E Community Home Page e2e.ti.com
Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265
Copyright ©2011, Texas Instruments Incorporated
