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 ca-
pacitor, however, a 1 F solid tantalum capacitor should be
used on the input. A 0.1 F 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 capaci-
tance.
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
-55C to +150C for LM123, -40C to +125C for LM323A,
and 0C to +125C for LM323. A hermetic TO-3 package is
used for high reliability and low thermal resistance.
Features
n
Guaranteed 1% initial accuracy (A version)
n
3 amp output current
n
Internal current and thermal limiting
n
0.01
typical output impedance
n
7.5V minimum input voltage
n
30W power dissipation
n
P
+
Product Enhancement tested
Connection Diagram
Typical Applications
Metal Can Package
DS007771-2
Order Number LM123K STEEL, LM323AK STEEL or LM323K STEEL
See NS Package Number K02A
Order Number LM123K/883
See NS Package Number K02C
Basic 3 Amp Regulator
DS007771-3
*Required if LM123 is more than 4" from filter capacitor.
Regulator is stable with no load capacitor into resistive loads.
April 1998
LM123/LM323A/LM323
3-Amp,
5-V
olt
Positive
Regulator
1999 National Semiconductor Corporation
DS007771
www.national.com
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
-55C to +150C
LM323A
-40C to +125C
LM323
0C to +125C
Storage Temperature Range
-65C to +150C
Lead Temperature (Soldering, 10 sec.)
300C
ESD Tolerance (Note 5)
2000V
LM123 Electrical Characteristics
(Note 2)
Parameter
Conditions
LM123
Units
Min
Typ
Max
Output Voltage
T
j
= 25C
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
= 25C
5
25
mV
7.5V
V
IN
15V
Load Regulation (Note 4)
T
j
= 25C, 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
= 25C
40
Vrms
10 Hz
f
100 kHz
Short Circuit Current Limit
T
j
= 25C
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
= 25C
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
= 25C
5
10
5
25
mV
7.5V
V
IN
15V
Load Regulation (Note 4)
T
j
= 25C, 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
= 25C
40
40
Vrms
10 Hz
f
100 kHz
Short Circuit Current Limit
T
j
= 25C
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
Thermal Resistance Junction
to Case (Note 3)
2
2
C/W
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2
LM323A/LM323 Electrical Characteristics
(Note 2) (Continued)
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 -55C
T
j
+150C for the LM123, -40C
T
j
+125C for the LM323A, and 0C
T
j
+125C 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 35C/W. With a heat sink, the effective thermal resistance can only approach the
specified values of 2C/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 k
in series with 100 pF.
Typical Performance Characteristics
Maximum Average Power
Dissipation for LM123
DS007771-9
Maximum Average Power
Dissipation for LM323A, LM323
DS007771-10
Output Impedance
DS007771-11
Peak Available Output Current
DS007771-12
Short Circuit Current
DS007771-13
Ripple Rejection
DS007771-14
Dropout Voltage
DS007771-15
Line Transient Response
DS007771-16
Output Voltage
DS007771-17
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3
Typical Performance Characteristics
(Continued)
Typical Applications
Quiescent Current
DS007771-18
Load Transient Response
DS007771-19
Output Noise Voltage
DS007771-20
10 Amp Regulator with Complete Overload Protection
DS007771-6
*Select for 20 mA Current from Unregulated Negative Supply
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4
Typical Applications
(Continued)
Adjustable Regulator 0V-10V
@
3A
DS007771-7
A
1
-- LM101A
C
1
-- 2 F Optional -- Improves Ripple Rejection, Noise, and Transient Response
Trimming Output to 5V
DS007771-8
Adjustable Output 5V-10V 0.1% Regulation
DS007771-4
*Select to Set Output Voltage
*
*
Select to Draw 25 mA from V
-
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5
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