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Linear LT138A LT338A LM138 LM338 Data Handbook

Summary

The LT138A/LT338A series is a high-performance adjustable voltage regulator designed for demanding power applications requiring superior stability and reliability. This device guarantees stable output current up to 5A across a wide range of voltages while excelling at handling large transient load spikes. The technical manual provides comprehensive specifications, detailed electrical characteristics, thermal parameters, and typical application guidelines, making it an essential component for engineers designing circuits such as lighting controllers or high-power drivers who require precise, regulated voltage output.

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Page 1 Text Content

查询LM138供应商

LT138A/LT338A LM138/LM338 5A Positive Adjustable Voltage Regulator

FEATURES DESCRIPTIO Guaranteed 1% Initial Tolerance The LT®138A series of adjustable regulators provide 5A Guaranteed 0.3% Load Regulation output current over an output voltage range of 1.2V to 32V. Guaranteed 5A Output Current The internal voltage reference is trimmed to less than 1%, 100% Thermal Limit Burn-In enabling a very tight output voltage. In addition to excel- 12A Transient Output Current lent line and load regulation, with full overload protection,

the LT138A incorporates new current limiting circuitry allowing large transient load currents to be handled for

APPLICATIO S

short periods. Transient load currents of up to 12A can be High Power Linear Regulator supplied without limiting, eliminating the need for a large Battery Chargers output capacitor.

Power Driver

The LT138A is an improved version of the popular LM138

Constant-Current Regulator

with improved circuit design and advanced process tech-

OU TP UT OL TA GE RR OR

niques to provide superior performance and reliability. The graph below shows the significant improvement in output voltage tolerance achieved by using the LT138A or LT338A. , LTC and LT are registered trademarks of Linear Technology Corporation.

TYPICAL APPLICATIO

Parallel Regulators for Higher Current* Output Voltage Error

LT338A

VINVIN VOUT

2% RESISTORS

LM338

1% RESISTORS

LT350A LM338

LT338A

VIN VOUT

ADJ 121Ω 2% RESISTORS 1% LT338A

1% RESISTORS

365Ω 1% 138/338 TA01

OUTPUT VOLTAGE (V)

THIS CIRCUIT WILL NOT WORK WITH LM VERSION DEVICES

138A/338A TA02

CURRENT SHARING RESISTORS DEGRADE REGULATION TO 1%

Page Summary Contents For Linear LT138A LT338A LM138 LM338 Data Handbook

Page 1 查询LM138供应商 LT138A/LT338A LM138/LM338 5A Positive Adjustable Voltage Regulator FEATURES DESCRIPTIO Guaranteed 1% Initial Tolerance The LT®138A series of adjustable regulators provide 5A Guaranteed 0.3%...
Page 2 LT138A/LT338A LM138/LM338 XI ARBSOLUTE TI (Note 1) Power Dissipation Internally Limited Storage Temperature Range –65°C to 150°C Input-to-Output Voltage Differential 35V Lead Temperature (Soldering, 1...
Page 3 LT138A/LT338A LM138/LM338 ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. (Note 2) LT138A LM13...
Page 4 LT138A/LT338A RI PP LE EJ EC TI ON (d B) RE FE RE NC VO LT AG (V OU TP UT OL TA GE EV IA TI ON LM138/LM338 TYPICAL PERFOR A CE CHARACTERISTICS Load Regulation Dropout Voltage Adjustment Current 0.2 VI...
Page 5 LT138A/LT338A OU TP UT UR RE NT (A LM138/LM338 TYPICAL PERFOR A CE CHARACTERISTICS IN PU VO LT AG OU TP UT OL TA GE CH AN GE (V DE VI AT IO (V Current Limit Current Limit Current Limit PEAK CURRENT LI...
Page 6 LT138A/LT338A LM138/LM338 APPLICATIONS INFORMATION For example, using 2% resistors and ±4% tolerance for (80d B) can be accomplished by adding a 10µF capacitor VREF, calculations will show that the ex...
Page 7 LT138A/LT338A LM138/LM338 APPLICATIONS INFORMATION negative side of the load. Although it may not be immedi- PARASITIC LT338A ately obvious, best load regulation is obtained when the LINE RESISTANCE V...
Page 8 LT138A/LT338A LM138/LM338 TYPICAL APPLICATIONS 5V Regulator with Shutdown LT338A VIN VIN VOUT 5V ADJ 121Ω 1%1µF TTL 2N3904 138A/338A TA05 Temperature Compensated Lead Acid Battery Charger 3A LT338A VI...
Page 9 LT138A/LT338A LM138/LM338 SCHE ATIC DIAGRA LT138A/LT338A p FC1 UT AD 8A /3 SS
Page 10 LT138A/LT338A LM138/LM338 PACKAGE DESCRIPTION Dimensions in inches (millimeters) unless otherwise noted. K Package 2-Lead TO-3 Metal Can (LTC DWG # 05-08-1310) (3.86 – 4.09) DIA, 2PLCS K2 (TO-3) 1098
Page 11 LT138A/LT338A LM138/LM338 PACKAGE DESCRIPTION Dimensions in inches (millimeters) unless otherwise noted. P Package 3-Lead Plastic TO-3P (Similar to TO-247) (LTC DWG # 05-08-1450) (8.255) MOUNTING HOLE...
Page 12 LT138A/LT338A LM138/LM338 TYPICAL APPLICATIONS Lamp Flasher Automatic Light Control LT338A LT338A 15V VIN VOUT VIN VOUT ADJ ADJ 1k 138A/338A TA09 138A/338A TA08 Protected High Current Lamp Driver LT33...

Manual Details

Brand Linear
Pages 12
File Size 188.63 KB
Published June 06, 2026
33 views

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Frequently Asked Questions

What is the maximum transient load current this regulator can handle?

It can supply transient load currents of up to 12A without limiting.

Does this regulator require a large output capacitor compared to older models?

No, the new current limiting circuitry eliminates the need for a larger output capacitor when handling transient loads.

What is the required minimum input-to-output voltage difference?

The Input-to-Output Voltage Differential must be at least 3.5V.

Which operating range should I consider if my system needs flexibility in cold weather?

The LT138A/LM138 offers a precondition operating junction temperature range from -55°C to 150°C.