LM338 PDF Datasheet – 5A, Adjustable Voltage Regulator

This post explains for the regulator.

The Part Number is LM338.

The function of this semiconductor is 5A, Adjustable Voltage Regulator.

The package is TO-3 Type

Manufacturer: STMicroelectronics

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LM338 image

What is LM338?

The LM138, LM238, LM338 are adjustable 3-terminal positive voltage regulators capable of
supplying in excess of 5 A over a 1.2 V to 32 V 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 current limiting. The current limit circuitry allows peak currents of up to 12 A to be drawn from the regulator for short periods of time.

One of the key advantages of the LM338 is its high efficiency, which is achieved through its use of a low dropout voltage (LDV) design. This means that the voltage drop between the input and output pins is very low, typically around 1.5 volts, which reduces power dissipation and increases efficiency.

The LM338 is commonly used in power supply circuits, battery charging circuits, and voltage regulation applications where a stable and adjustable output voltage is required. It is also used in audio amplifiers, signal generators, and other electronic devices that require high current and low dropout voltage.


1. Guaranteed 7 A peak output current

2. Guaranteed 5 A output current

3. Adjustable output down to 1.2 V

4. Line regulation typically 0.005 %/V

5. Load regulation typically 0.1 %

6. Guaranteed thermal regulation

7. Current limit constant with temperature

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LM338 Datasheet PDF