LM338 Regulator: Circuit, Price and Pinout

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Published: 31 August 2021 | Last Updated: 31 August 2021

5360

LM338T/NOPB

LM338T/NOPB

Texas Instruments

Adjustable 2.54mm Tin LM338 PMIC 3 TO-220-3

Purchase Guide

Adjustable 2.54mm Tin LM338 PMIC 3 TO-220-3

Hello, everyone. I am Rose. Today we will discuss LM338. LM338 is a 5-Amp Adjustable Regulators. This article mainly introduce circuit, price, pinout and other detailed information about Texas Instruments LM338.

 This video will show you how to build a very simple constant current regulator based on the LM338 linear regulator.

Voltlog #128 - LM338 Constant Current Regulator Circuit

LM338 Description

LM338 is a three terminal positive adjustable voltage regulator IC available in TO-220 package. It provides stable output voltage for example if the user set its output on 5V then it will provide stable 5V output no matter if the input voltage is fluctuating. But the user or designer of the circuit has to keep one more thing in mind that the input voltage must be 2V to 3V higher than the output voltage in any condition. 


In order to solve this problem the user should provide higher input voltage than the output for example for 5V output the input voltage can be 12V or more so if the input voltage fluctuates 3V to 5V then we still get a stable 5V at the output. One best example of this can be a solar panel that changes the output voltage frequently on a partly cloudy day.


This IC is adjustable from 1.2V to 32V DC and the maximum input voltage can be applied to the IC is 40V. LM338 can be easily used in the place of LM317 if there is a requirement for higher amperes, it is capable to deliver load of up to 5A output current. However, this can also be done by using one or two high current transistors with the LM317 IC but using LM388 is still a good option if the output current requirement is under 5A.


Moreover LM338 requires very low external components because all the important circuitry is built inside the IC and hence at the output it requires only two capacitors (in some conditions), and two external resistors to adjust the output voltage. There is also an output voltage calculator available online for the IC which shows the value of the resistor to be used for a specific output.


LM338 Pinout

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LM338 CAD Model

Symbol

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Footprint

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3D Model

LM338 3D Model.jpg

LM338 Features

-Available in 3 lead transistor TO-220 package

-Guaranteed 5A output current

-Guaranteed 7A peak output current

-Voltage adjustable from 1.2V to 32V

-Less external components required

-Only two external resistors are required for output adjustment.

-Short circuit protection capability

-Overheat shutdown functionality

-Reliable to use in commercial applications

-Maximum input voltage is 40V DC

-Low standby current

-Low price

-Adjustable output down to 1.2V

-Guaranteed thermal regulation

-Current limit constant with temperature

-P+ Product Enhancement tested

-Line regulation typically 0.005 %/V

-Load regulation typically 0.1 %


Specifications

Texas Instruments LM338T/NOPB technical specifications, attributes, parameters and parts with similar specifications to Texas Instruments LM338T/NOPB.
  • Type
    Parameter
  • Lifecycle Status

    Lifecycle Status refers to the current stage of an electronic component in its product life cycle, indicating whether it is active, obsolete, or transitioning between these states. An active status means the component is in production and available for purchase. An obsolete status indicates that the component is no longer being manufactured or supported, and manufacturers typically provide a limited time frame for support. Understanding the lifecycle status is crucial for design engineers to ensure continuity and reliability in their projects.

    ACTIVE (Last Updated: 3 days ago)
  • Factory Lead Time
    6 Weeks
  • Contact Plating

    Contact plating (finish) provides corrosion protection for base metals and optimizes the mechanical and electrical properties of the contact interfaces.

    Tin
  • Mount

    In electronic components, the term "Mount" typically refers to the method or process of physically attaching or fixing a component onto a circuit board or other electronic device. This can involve soldering, adhesive bonding, or other techniques to secure the component in place. The mounting process is crucial for ensuring proper electrical connections and mechanical stability within the electronic system. Different components may have specific mounting requirements based on their size, shape, and function, and manufacturers provide guidelines for proper mounting procedures to ensure optimal performance and reliability of the electronic device.

    Through Hole
  • Mounting Type

    The "Mounting Type" in electronic components refers to the method used to attach or connect a component to a circuit board or other substrate, such as through-hole, surface-mount, or panel mount.

    Through Hole
  • Package / Case

    refers to the protective housing that encases an electronic component, providing mechanical support, electrical connections, and thermal management.

    TO-220-3
  • Number of Pins
    3
  • Weight
    2.299997g
  • Operating Temperature

    The operating temperature is the range of ambient temperature within which a power supply, or any other electrical equipment, operate in. This ranges from a minimum operating temperature, to a peak or maximum operating temperature, outside which, the power supply may fail.

    0°C~125°C
  • Packaging

    Semiconductor package is a carrier / shell used to contain and cover one or more semiconductor components or integrated circuits. The material of the shell can be metal, plastic, glass or ceramic.

    Tube
  • JESD-609 Code

    The "JESD-609 Code" in electronic components refers to a standardized marking code that indicates the lead-free solder composition and finish of electronic components for compliance with environmental regulations.

    e3
  • Pbfree Code

    The "Pbfree Code" parameter in electronic components refers to the code or marking used to indicate that the component is lead-free. Lead (Pb) is a toxic substance that has been widely used in electronic components for many years, but due to environmental concerns, there has been a shift towards lead-free alternatives. The Pbfree Code helps manufacturers and users easily identify components that do not contain lead, ensuring compliance with regulations and promoting environmentally friendly practices. It is important to pay attention to the Pbfree Code when selecting electronic components to ensure they meet the necessary requirements for lead-free applications.

    yes
  • Part Status

    Parts can have many statuses as they progress through the configuration, analysis, review, and approval stages.

    Active
  • Moisture Sensitivity Level (MSL)

    Moisture Sensitivity Level (MSL) is a standardized rating that indicates the susceptibility of electronic components, particularly semiconductors, to moisture-induced damage during storage and the soldering process, defining the allowable exposure time to ambient conditions before they require special handling or baking to prevent failures

    1 (Unlimited)
  • Number of Terminations
    3
  • Termination

    Termination in electronic components refers to the practice of matching the impedance of a circuit to prevent signal reflections and ensure maximum power transfer. It involves the use of resistors or other components at the end of transmission lines or connections. Proper termination is crucial in high-frequency applications to maintain signal integrity and reduce noise.

    Through Hole
  • ECCN Code

    An ECCN (Export Control Classification Number) is an alphanumeric code used by the U.S. Bureau of Industry and Security to identify and categorize electronic components and other dual-use items that may require an export license based on their technical characteristics and potential for military use.

    EAR99
  • Power Rating

    The "Power Rating" of an electronic component refers to the maximum amount of power that the component can handle or dissipate without being damaged. It is typically measured in watts and is an important specification to consider when designing or selecting components for a circuit. Exceeding the power rating of a component can lead to overheating, malfunction, or even permanent damage. It is crucial to ensure that the power rating of each component in a circuit is sufficient to handle the power levels expected during normal operation to maintain the reliability and longevity of the electronic system.

    25W
  • Max Power Dissipation

    The maximum power that the MOSFET can dissipate continuously under the specified thermal conditions.

    25W
  • Terminal Position

    In electronic components, the term "Terminal Position" refers to the physical location of the connection points on the component where external electrical connections can be made. These connection points, known as terminals, are typically used to attach wires, leads, or other components to the main body of the electronic component. The terminal position is important for ensuring proper connectivity and functionality of the component within a circuit. It is often specified in technical datasheets or component specifications to help designers and engineers understand how to properly integrate the component into their circuit designs.

    SINGLE
  • Number of Functions
    1
  • Terminal Pitch

    The center distance from one pole to the next.

    2.54mm
  • Current Rating

    Current rating is the maximum current that a fuse will carry for an indefinite period without too much deterioration of the fuse element.

    5A
  • Base Part Number

    The "Base Part Number" (BPN) in electronic components serves a similar purpose to the "Base Product Number." It refers to the primary identifier for a component that captures the essential characteristics shared by a group of similar components. The BPN provides a fundamental way to reference a family or series of components without specifying all the variations and specific details.

    LM338
  • Pin Count

    a count of all of the component leads (or pins)

    3
  • Number of Outputs
    1
  • Output Voltage

    Output voltage is a crucial parameter in electronic components that refers to the voltage level produced by the component as a result of its operation. It represents the electrical potential difference between the output terminal of the component and a reference point, typically ground. The output voltage is a key factor in determining the performance and functionality of the component, as it dictates the level of voltage that will be delivered to the connected circuit or load. It is often specified in datasheets and technical specifications to ensure compatibility and proper functioning within a given system.

    37V
  • Output Type

    The "Output Type" parameter in electronic components refers to the type of signal or data that is produced by the component as an output. This parameter specifies the nature of the output signal, such as analog or digital, and can also include details about the voltage levels, current levels, frequency, and other characteristics of the output signal. Understanding the output type of a component is crucial for ensuring compatibility with other components in a circuit or system, as well as for determining how the output signal can be utilized or processed further. In summary, the output type parameter provides essential information about the nature of the signal that is generated by the electronic component as its output.

    Adjustable
  • Max Output Current

    The maximum current that can be supplied to the load.

    5A
  • Max Supply Voltage

    In general, the absolute maximum common-mode voltage is VEE-0.3V and VCC+0.3V, but for products without a protection element at the VCC side, voltages up to the absolute maximum rated supply voltage (i.e. VEE+36V) can be supplied, regardless of supply voltage.

    40V
  • Min Supply Voltage

    The minimum supply voltage (V min ) is explored for sequential logic circuits by statistically simulating the impact of within-die process variations and gate-dielectric soft breakdown on data retention and hold time.

    3V
  • Output Configuration

    Output Configuration in electronic components refers to the arrangement or setup of the output pins or terminals of a device. It defines how the output signals are structured and how they interact with external circuits or devices. The output configuration can determine the functionality and compatibility of the component in a circuit design. Common types of output configurations include single-ended, differential, open-drain, and push-pull configurations, each serving different purposes and applications in electronic systems. Understanding the output configuration of a component is crucial for proper integration and operation within a circuit.

    Positive
  • Power Dissipation

    the process by which an electronic or electrical device produces heat (energy loss or waste) as an undesirable derivative of its primary action.

    25W
  • Quiescent Current

    The quiescent current is defined as the current level in the amplifier when it is producing an output of zero.

    3mA
  • Max Output Voltage

    The maximum output voltage refers to the dynamic area beyond which the output is saturated in the positive or negative direction, and is limited according to the load resistance value.

    37V
  • Voltage - Output (Min/Fixed)

    Voltage - Output (Min/Fixed) refers to the minimum fixed output voltage level that an electronic component, such as a voltage regulator or power supply, is designed to provide under specified load conditions. This parameter ensures that the device consistently delivers a reliable voltage that meets the requirements of the connected circuits or components. It is critical for applications where stable and predictable voltage is necessary for proper operation.

    1.24V
  • Min Input Voltage

    The parameter "Min Input Voltage" in electronic components refers to the minimum voltage level that must be applied to the component for it to operate within its specified parameters. This value is crucial as providing a voltage below this minimum threshold may result in the component malfunctioning or not functioning at all. It is important to adhere to the specified minimum input voltage to ensure the proper operation and longevity of the electronic component. Failure to meet this requirement may lead to potential damage to the component or the overall system in which it is used.

    4.2V
  • Protection Features

    Protection features in electronic components refer to the built-in mechanisms or functionalities designed to safeguard the component and the overall system from various external factors or internal faults. These features are crucial for ensuring the reliability, longevity, and safety of the electronic device. Common protection features include overvoltage protection, overcurrent protection, reverse polarity protection, thermal protection, and short-circuit protection. By activating these features when necessary, the electronic component can prevent damage, malfunctions, or hazards that may arise from abnormal operating conditions or unforeseen events. Overall, protection features play a vital role in enhancing the robustness and resilience of electronic components in diverse applications.

    Over Temperature, Short Circuit
  • PSRR

    PSRR stands for Power Supply Rejection Ratio. It is a measure of how well a device, such as an amplifier or a voltage regulator, can reject variations in the power supply voltage. A high PSRR value indicates that the device is able to maintain its performance even when the power supply voltage fluctuates. This parameter is important in ensuring stable and reliable operation of electronic components, especially in applications where the power supply voltage may not be perfectly regulated. A good PSRR helps to minimize noise and interference in the output signal of the device.

    75dB ~ 60dB (120Hz)
  • Reference Voltage

    A voltage reference is an electronic device that ideally produces a fixed (constant) voltage irrespective of the loading on the device, power supply variations, temperature changes, and the passage of time. Voltage references are used in power supplies, analog-to-digital converters, digital-to-analog converters, and other measurement and control systems. Voltage references vary widely in performance; a regulator for a computer power supply may only hold its value to within a few percent of the nominal value, whereas laboratory voltage standards have precisions and stability measured in parts per million.

    1.29V
  • Dropout Voltage

    Dropout voltage is the input-to-output differential voltage at which the circuit ceases to regulate against further reductions in input voltage; this point occurs when the input voltage approaches the output voltage.

    3mV
  • Dropout Voltage1-Nom

    Dropout Voltage1-Nom is a parameter commonly found in voltage regulators and power management ICs. It refers to the minimum voltage difference required between the input voltage and the output voltage for the regulator to maintain regulation. In other words, it is the minimum voltage drop that the regulator can handle while still providing a stable output voltage. This parameter is important to consider when designing power supply circuits to ensure that the regulator can operate within its specified voltage range and maintain proper regulation under varying load conditions.

    2.7V
  • Min Output Voltage

    Min Output Voltage refers to the lowest voltage level that an electronic component, such as a voltage regulator or power supply, can provide reliably under specified conditions. It indicates the minimum threshold required for proper operation of connected devices. Operating below this voltage may lead to device malfunction or failure to operate as intended.

    1.2V
  • Power Supply Rejection Ratio (PSRR)

    Power Supply Rejection Ratio (PSRR) is a measure of how well an electronic component, such as an operational amplifier or voltage regulator, can reject changes in its supply voltage. It indicates the ability of the component to maintain a stable output voltage despite fluctuations in the input supply voltage. A higher PSRR value signifies better performance in rejecting noise and variations from the power supply, leading to improved signal integrity and more reliable operation in electronic circuits. PSRR is typically expressed in decibels (dB).

    75dB
  • Load Regulation-Max(%)

    Load Regulation-Max(%) is a measure of how much the output voltage of a power supply or voltage regulator changes in response to variations in load current. It is expressed as a percentage of the nominal output voltage and indicates the maximum deviation from the set voltage when the load shifts from no load to full load. A lower value of load regulation signifies better performance, as it indicates that the output voltage remains stable under varying load conditions.

    1%
  • Line Regulation-Max (%/V)

    Line regulation refers to the ability of an electronic component, such as a voltage regulator, to maintain a stable output voltage despite variations in the input voltage. The parameter "Line Regulation-Max (%/V)" specifies the maximum percentage change in the output voltage for a given change in the input voltage. For example, if the Line Regulation-Max is 0.1%/V, it means that the output voltage will change by a maximum of 0.1% for every 1V change in the input voltage. A lower value for Line Regulation-Max indicates better performance and stability of the component in maintaining a consistent output voltage under varying input conditions. It is an important parameter to consider when designing or selecting electronic components for applications where voltage stability is critical.

    0.06
  • Height
    4.7mm
  • Length
    14.986mm
  • Width
    10.16mm
  • Thickness

    Thickness in electronic components refers to the measurement of how thick a particular material or layer is within the component structure. It can pertain to various aspects, such as the thickness of a substrate, a dielectric layer, or conductive traces. This parameter is crucial as it impacts the electrical, mechanical, and thermal properties of the component, influencing its performance and reliability in electronic circuits.

    4.572mm
  • REACH SVHC

    The parameter "REACH SVHC" in electronic components refers to the compliance with the Registration, Evaluation, Authorization, and Restriction of Chemicals (REACH) regulation regarding Substances of Very High Concern (SVHC). SVHCs are substances that may have serious effects on human health or the environment, and their use is regulated under REACH to ensure their safe handling and minimize their impact.Manufacturers of electronic components need to declare if their products contain any SVHCs above a certain threshold concentration and provide information on the safe use of these substances. This information allows customers to make informed decisions about the potential risks associated with using the components and take appropriate measures to mitigate any hazards.Ensuring compliance with REACH SVHC requirements is essential for electronics manufacturers to meet regulatory standards, protect human health and the environment, and maintain transparency in their supply chain. It also demonstrates a commitment to sustainability and responsible manufacturing practices in the electronics industry.

    No SVHC
  • Radiation Hardening

    Radiation hardening is the process of making electronic components and circuits resistant to damage or malfunction caused by high levels of ionizing radiation, especially for environments in outer space (especially beyond the low Earth orbit), around nuclear reactors and particle accelerators, or during nuclear accidents or nuclear warfare.

    No
  • RoHS Status

    RoHS means “Restriction of Certain Hazardous Substances” in the “Hazardous Substances Directive” in electrical and electronic equipment.

    ROHS3 Compliant
  • Lead Free

    Lead Free is a term used to describe electronic components that do not contain lead as part of their composition. Lead is a toxic material that can have harmful effects on human health and the environment, so the electronics industry has been moving towards lead-free components to reduce these risks. Lead-free components are typically made using alternative materials such as silver, copper, and tin. Manufacturers must comply with regulations such as the Restriction of Hazardous Substances (RoHS) directive to ensure that their products are lead-free and environmentally friendly.

    Lead Free
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LM338 Alternatives

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LM338 Functional Block Diagram

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LM338 Layout Example

Layout Example.png

LM338 Circuit

5A Current Regulator Circuit.png12-V Battery Charger.png

                                  5A Current Regulator Circuit                           12-V Battery Charger Circuit

LM338 Applications

-Used in commercial power supplies

-Used in educational power supplies

-Used in lab power supplies

-Used in voltage step down circuits

-Used in battery chargers circuits

-Used in solar power supplies

-Used in solar battery charger circuits

-Used in microcontroller Applications

-Used in DC to DC converters Circuits

-Used in portable Instrument applications

-Used in adjustable power supplies

-Used in constant current regulators


LM338 Package

Package.png

LM338 Manufacturer

Texas Instruments Incorporated (TI) is an American technology company headquartered in Dallas, Texas, that designs and manufactures semiconductors and various integrated circuits, which it sells to electronics designers and manufacturers globally.[6] It is one of the top 10 semiconductor companies worldwide based on sales volume.The company's focus is on developing analog chips and embedded processors, which account for more than 80% of its revenue.TI also produces TI digital light processing technology and education technology products including calculators, microcontrollers and multi-core processors. The company holds 45,000 patents worldwide as of 2016.


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Parts with Similar Specs

The three parts on the right have similar specifications to Texas Instruments & LM338T/NOPB.
Frequently Asked Questions

1.What is the difference between the LM138 chip and the LM338 chip? Are the parameters the same?

The parameters in the LM138 chip and the LM338 chip are basically the same, mainly the temperature of the LM138 chip is -55-150 degrees, and the temperature of the LM338 chip is 0-125 degrees. In addition, the ripple factor should be smaller.

2.What are the precautions for the use of LM338?

(1)LM338 is a series-adjustable regulated power supply, so when it outputs a small voltage and a large current, the tube voltage drop is large, the power consumption of the tube is correspondingly large, and the temperature will be very high, so the radiator should be enlarged when using it.
(2)The filter capacitor of the power supply should be large, and a small capacitor should be connected in parallel to filter the high frequency, and the capacitor should be as close as possible to the pin.
(3)Due to the protection circuit, try not to connect large capacitors and capacitive loads to the output terminal, otherwise the protection circuit may malfunction.

3.What are the advantages and disadvantages of LM338 and LM317 as an adjustable power supply?

In terms of output current, the maximum output current of LM338 is larger (5A), and the maximum output current of LM317 is 1.5A;
In terms of output voltage adjustment range, LM317 is larger than LM338, the adjustment range of LM317 is 1.2V~37V, and the adjustment range of LM338 is 1.2V~32V;
In terms of the maximum input and output voltage difference, LM317 is also slightly larger than LM338, LM317 is 40V, LM338 is 35V.
LM338T/NOPB

Texas Instruments

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