LM338T/NOPB National Semiconductor, LM338T/NOPB Datasheet



Manufacturer Part Number
National Semiconductor
Voltage Regulatorr

Specifications of LM338T/NOPB

Regulator Topology
Positive Adjustable
Voltage - Output
1.2 ~ 32 V
Voltage - Input
4.2 ~ 40 V
Number Of Regulators
Current - Output
Current - Limit (min)
Operating Temperature
0°C ~ 125°C
Mounting Type
Through Hole
Package / Case
TO-220-3 (Straight Leads)
Current, Output
5 A
Package Type
Regulation, Line
0.005 %/V
Regulation, Load
0.1 %
Regulator Type
Positive Voltage Out
Resistance, Thermal, Junction To Case
4 °C/W
Temperature, Operating, Range
0 to +125 °C
Voltage, Input
-0.3 to +40 V
Voltage, Noise
0.003 %
Voltage, Output
1.2 to 32 V
Voltage, Supply, Rejection Ratio
60 dB
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Voltage - Dropout (typical)
Lead Free Status / Rohs Status
RoHS Compliant part Electrostatic Device
Other names

Available stocks

Part Number
Part Number:
60 959
Part Number:
© 1999 National Semiconductor Corporation
5-Amp Adjustable Regulators
General Description
The LM138 series of adjustable 3-terminal positive voltage
regulators is capable of supplying in excess of 5A over a
1.2V to 32V output range. They are exceptionally easy to
use and require only 2 resistors to set the output voltage.
Careful circuit design has resulted in outstanding load and
line regulation — comparable to many commercial power
supplies. The LM138 family is supplied in a standard 3-lead
transistor package.
A unique feature of the LM138 family is time-dependent cur-
rent limiting. The current limit circuitry allows peak currents
of up to 12A to be drawn from the regulator for short periods
of time. This allows the LM138 to be used with heavy tran-
sient loads and speeds start-up under full-load conditions.
Under sustained loading conditions, the current limit de-
creases to a safe value protecting the regulator. Also in-
cluded on the chip are thermal overload protection and safe
area protection for the power transistor. Overload protection
remains functional even if the adjustment pin is accidentally
Normally, no capacitors are needed unless the device is situ-
ated more than 6 inches from the input filter capacitors in
which case an input bypass is needed. An output capacitor
can be added to improve transient response, while bypass-
ing the adjustment pin will increase the regulator’s ripple re-
Connection Diagrams
Order Number LM138K STEEL or LM338K STEEL
See NS Package Number K02A
Metal Can Package
Bottom View
(See Physical Dimension section for further information)
Besides replacing fixed regulators or discrete designs, the
LM138 is useful in a wide variety of other applications. Since
the regulator is “floating” and sees 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, i.e., do not short-circuit output to ground.
The part numbers in the LM138 series which have a K suffix
are packaged in a standard Steel TO-3 package, while those
with a T suffix are packaged in a TO-220 plastic package.
The LM138 is rated for −55˚C T
is rated for 0˚C
n Guaranteed 7A peak output current
n Guaranteed 5A output current
n Adjustable output down to 1.2V
n Guaranteed thermal regulation
n Current limit constant with temperature
n P
n Output is short-circuit protected
n Adjustable power supplies
n Constant current regulators
n Battery chargers
Product Enhancement tested
See NS Package Number T03B
Order Number LM338T
Plastic Package
Front View
+150˚C, and the LM338
May 1998

LM338T/NOPB Summary of contents

Page 1

... DS009060-30 Bottom View Order Number LM138K STEEL or LM338K STEEL See NS Package Number K02A © 1999 National Semiconductor Corporation DS009060 Besides replacing fixed regulators or discrete designs, the LM138 is useful in a wide variety of other applications. Since the regulator is “floating” and sees only the input-to-output ...

Page 2

... Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. (Note 4) Power Dissipation Input/Output Voltage Differential Storage Temperature Electrical Characteristics Specifications with standard type face are for T ture Range. Unless otherwise specified, V ...

Page 3

Electrical Characteristics Symbol Parameter V Temperature Stability R/T I (Min) Minimum Load Current LOAD I Current Limit CL V RMS Output Noise OUT Ripple Rejection Ratio Long-Term Stability Thermal Resistance JC Junction to Case Thermal Resistance, ...

Page 4

Typical Performance Characteristics Temperature Stability DS009060-38 Ripple Rejection DS009060-41 Line Transient Response DS009060-44 Application Hints In operation, the LM138 develops a nominal 1.25V reference voltage between the output and adjustment terminal. REF The reference voltage is impressed across ...

Page 5

Application Hints (Continued) DS009060-6 FIGURE 1. Since the 50 µA current from the adjustment terminal repre- sents an error term, the LM138 was designed to minimize I and make it very constant with line and load changes. ADJ To do ...

Page 6

Application Hints (Continued) D1 protects against C1 D2 protects against C2 www.national.com DS009060-8 FIGURE 3. Regulator with Protection Diodes 6 ...

Page 7

Typical Applications Regulator and Voltage Reference DS009060-3 1.2V–25V Adjustable Regulator Temperature Controller Full output current not available at high input-output voltages † Optional — improves transient response. Output capacitors in the range of 1 µF to 1000 µF of aluminum ...

Page 8

Schematic Diagram www.national.com 8 ...

Page 9

Typical Applications Precision Power Regulator with Low Temperature Coefficient * Adjust for 3.75 across R1 Slow Turn-On 15V Regulator High Stability 10V Regulator Adjustable Regulator with Improved Ripple Rejection DS009060-13 † Solid tantalum * Discharges C1 if output is shorted ...

Page 10

Typical Applications (Continued) * Minimum load — 100 mA 5V Logic Regulator with Electronic Shutdown ** Minimum output 1.2V www.national.com 15A Regulator ** Light Controller DS009060-18 10 DS009060-17 DS009060-11 ...

Page 11

Typical Applications (Continued 240 , for LM138 Full output current not available at high input-output voltages 0 to 22V Regulator DS009060-19 12V Battery Charger 11 DS009060-20 www.national.com ...

Page 12

Typical Applications (Continued) Adjustable Current Regulator 5A Current Regulator DS009060-23 Adjusting Multiple On-Card Regulators with Single Control † Minimum load — ± * All outputs within 100 mV www.national.com Precision Current Limiter DS009060-21 Tracking Preregulator 12 DS009060-22 DS009060-24 ...

Page 13

Typical Applications (Continued 10k 100 10 100k Bandwidth 100 kHz Distortion 0.1% Use of R allows low charging ...

Page 14

Typical Applications (Continued) Adjustable 15A Regulator * Minimum load — 100 mA www.national.com Current Limited 6V Charger * Set max charge current THE 1000 µF is recommended to filter out input transients. DS009060-26 10A Regulator 14 ...

Page 15

Physical Dimensions inches (millimeters) unless otherwise noted Order Number LM138K or LM338K STEEL 2 Lead TO-3 Metal Can Package (K) NS Package Number K02A 3 Lead Molded TO-220 (T) Order Number LM338T NS Package Number T03B 15 www.national.com ...

Page 16

... National Semiconductor Asia Pacific Customer Fax: +49 (0) 1 80-530 85 86 Response Group Email: europe.support@nsc.com Tel: 65-2544466 Fax: 65-2504466 Tel: +49 (0) 1 80-532 78 32 Email: sea.support@nsc.com Tel: +49 (0) 1 80-534 16 80 National Semiconductor Japan Ltd. Tel: 81-3-5639-7560 Fax: 81-3-5639-7507 ...

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