LM338 Datasheet – 5-Amp Adjustable Regulator – National

Part Number: LM338, LM338K, LM338T

Function : 5-Amp Adjustable Regulator

Package: TO-3 Steel, TO-220 Type

Manufacturer: National Semiconductor


LM338 5A Adjustable Regulator



The LM138, LM338 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, LM338 family is supplied in a standard 3-lead transistor package.



LM338 datasheet pinout

1. Guaranteed 7A peak output current

2. Guaranteed 5A output current

3. Adjustable output down to 1.2V

4. Guaranteed thermal regulation

5. Current limit constant with temperature

LM338 vs LM317?

1. Input voltage range:

LM338 can handle higher input voltages of up to 40 volts, while LM317 is limited to 37 volts.

2. Output current capacity:

LM338 has a higher maximum output current of 5 amps, while LM317 is limited to 1.5 amps.

3. Dropout voltage:

LM338 has a lower dropout voltage than LM317, which means it can regulate output voltage more efficiently.

4. Thermal dissipation:

LM338 has higher thermal dissipation, which means it can handle higher power levels without overheating.

5. Price: LM338 is generally more expensive than LM317.

In summary, LM338 is suitable for applications that require higher input voltages, higher output current capacity, and more efficient voltage regulation. LM317 is suitable for applications where a lower output current is required and cost is a consideration.

Ultimately, the choice between LM338 and LM317 depends on the specific requirements of the circuit and the application in question.

LM338 Datasheet PDF

LM338 pdf


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