LM317 Voltage Regulator[Video+FAQ]: Pinout, Circuit, LM317 VS LM7805 and Datasheet

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Published: 27 April 2022 | Last Updated: 27 April 2022

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LM317T

LM317T

ON Semiconductor

Adjustable 2.54mm Tin LM317 PMIC 3 TO-220-3

Purchase Guide

Adjustable 2.54mm Tin LM317 PMIC 3 TO-220-3

The LM317 is an adjustable voltage linear regulator that can output 1.25 – 37V at up to 1.5A current with an input voltage range of 3–40V. This passage covers the LM317 regulator alternative, datasheet, applications, features, and other information on how to use and where to use this device.

This is a introduction video about LM317.

LM317 VOLTAGE REGULATOR Tutorial | How to use? | Pinout

LM317 Overview

 LM317 is an adjustable three-terminal regulator. The world's major IC manufacturers have similar products to choose from. Therefore, LM317 is a widely used series of integrated voltage regulators and can be used as a voltage regulator circuit in a DC-regulated power supply.


LM317 Pinout

lm317 pinout.jpg

Pin NumberPin NameDescription
1AdjustThese pins adjust the output voltage
2Output Voltage (Vout)The regulated output voltage set by the adjusted pin can be obtained from this pin
3Input Voltage (Vin)The input voltage which has to be regulated is given to this pin


Specifications

ON Semiconductor LM317T technical specifications, attributes, parameters and parts with similar specifications to ON Semiconductor LM317T.
  • 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.

    LAST SHIPMENTS (Last Updated: 3 days ago)
  • 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
    1.214012g
  • 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
  • Published
    2004
  • 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.

    Obsolete
  • 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
  • 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.

    20W
  • Packing Method

    The packing method in electronic components refers to the technique used to package and protect the component during shipping and handling. It encompasses various forms including tape and reel, tray, tube, or bulk packaging, each suited for different types of components and manufacturing processes. The choice of packing method can affect the ease of handling, storage, and the efficiency of assembly in automated processes. Additionally, it plays a crucial role in ensuring the reliability and integrity of the components until they are used in electronic devices.

    RAIL
  • Max Power Dissipation

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

    20W
  • 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
  • Peak Reflow Temperature (Cel)

    Peak Reflow Temperature (Cel) is a parameter that specifies the maximum temperature at which an electronic component can be exposed during the reflow soldering process. Reflow soldering is a common method used to attach electronic components to a circuit board. The Peak Reflow Temperature is crucial because it ensures that the component is not damaged or degraded during the soldering process. Exceeding the specified Peak Reflow Temperature can lead to issues such as component failure, reduced performance, or even permanent damage to the component. It is important for manufacturers and assemblers to adhere to the recommended Peak Reflow Temperature to ensure the reliability and functionality of the electronic components.

    235
  • Number of Functions
    1
  • Terminal Pitch

    The center distance from one pole to the next.

    2.54mm
  • Time@Peak Reflow Temperature-Max (s)

    Time@Peak Reflow Temperature-Max (s) refers to the maximum duration that an electronic component can be exposed to the peak reflow temperature during the soldering process, which is crucial for ensuring reliable solder joint formation without damaging the component.

    30
  • 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.

    LM317
  • Pin Count

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

    3
  • Number of Outputs
    1
  • Voltage - Input (Max)

    Voltage - Input (Max) is a parameter in electronic components that specifies the maximum voltage that can be safely applied to the input of the component without causing damage. This parameter is crucial for ensuring the proper functioning and longevity of the component. Exceeding the maximum input voltage can lead to electrical overstress, which may result in permanent damage or failure of the component. It is important to carefully adhere to the specified maximum input voltage to prevent any potential issues and maintain the reliability of the electronic system.

    40V
  • 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.

    1.5A
  • 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
  • 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
  • Number of Regulators

    A regulator is a mechanism or device that controls something such as pressure, temperature, or fluid flow. The voltage regulator keeps the power level stabilized. A regulator is a mechanism or device that controls something such as pressure, temperature, or fluid flow.

    1
  • 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.

    1.3V
  • 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.

    2V
  • 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.

    3V
  • 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).

    60dB
  • Min Current Limit

    Min Current Limit is a parameter in electronic components that refers to the minimum amount of current that must flow through the component to ensure proper operation. This parameter is important because if the current falls below this limit, the component may not function as intended or may even be damaged. Manufacturers specify the minimum current limit to help users understand the operating conditions and limitations of the component. It is crucial to ensure that the current flowing through the component remains above the specified minimum limit to maintain its performance and reliability.

    1.5A
  • 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.

    5.8%
  • Height
    9.15mm
  • Length
    10.4mm
  • Width
    4.6mm
  • 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.

    RoHS 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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LM317 CAD Models

Symbol

QQ截图20220427152223.jpg

Footprint

QQ截图20220427152233.jpg

3D Models

3d1.jpg


LM317 Features

  • Output voltage range adjustable from 1.25V to 37V

  • Output current greater than 1.5A

  • Internal short-circuit current limiting

  • Thermal overload protection

  • Output safe-area compensation


LM317 Applications

  • Used for Positive voltage regulations

  • Variable power supply

  • Current limiting circuits

  • Reverse polarity circuits

  • Commonly used in Desktop PC, DVDs, and other consumer products

  • Used in motor control circuits


LM317 Alternatives

LM317 Equivalents

Where to use LM317?

    When it comes to variable voltage control, the LM317 is almost certainly the top choice. It can be used as a variable voltage regulator, a fixed voltage regulator, a current limiter, a battery charger, an AC voltage regulator, and even an adjustable current regulator. One significant disadvantage of this IC is that it has a voltage drop of roughly 2.5 across it during regulation, so if you want to avoid that problem, look into the other equivalent ICs listed above.

     So, if you need a variable voltage regulator that can supply current up to 1.5A, this regulator IC could be a good fit for your application.


How to use LM317?

LM317 is a 3-terminal regulator IC and it is very simple to use. It has many application circuits in its datasheet, but this IC is known for being used as a variable voltage regulator. So, let’s look into how to use this IC as a variable voltage regulator.

 

As said earlier the IC has 3 pins, in which the input voltage is supplied to pin3 (VIN) then using a pair of resistors (potential divider) we set a voltage at pin 1 (Adjust) which will decide the output voltage of the IC that is given out at pin 2 (VOUT). Now to make it act as a variable voltage regulator we have to set variable voltages at pin 1 which can be done by using a potentiometer in the potential divider. The below circuit is designed to take 12V (you can supply up to 24V) as input and regulate it from 1.25V to 10V.

where to use.jpg

The Resistor R1 (1K) and the potentiometer (10k) together create a potential difference in adjusting the pin which regulates the output pin accordingly. The formulae to calculate the output voltage based on the value of resistors is

                                                        VOUT = 1.25 × (1 + (R2/R1))

Now, let’s verify this formula for the above circuit. The value of R1 is 1000 ohms and the value of R2 (potentiometer) is 5000 because it is a 10k potentiometer placed at 50% (50/100 of 1000 is 5000).

Vout  = 1.25 × (1 + (5000/1000))

         = 1.25 × 6

         = 7.5V

And the simulation shows 7.7V which is pretty much close. You can vary the output voltage by simply varying the potentiometer. In our circuit, a motor is connected as a load that consumes around 650mA you can connect any load up to 1.5A.

The same formulae can also be used to calculate the value of the resistor for your required output voltage. One easy way to do this is to use this online calculator to randomly substitute the value of resistors you have and check which output voltage you will get.


LM317 VS LM7805

  • LM317 is an adjustable voltage regulator, while LM7805 is the constant voltage regulator.

  • LM317 can give an adjustable output voltage in the range of 1.5V to 37V, whereas LM7805 can only give an output voltage of 5V.

  • What’s more, LM317 has the capability to give an output current of more than 1.5A whereas LM7805 can only give an output current only up to 1.5A.

  • LM317 requires more external components (adjustment pot or precision resistors to set the voltage divider etc.) as compared to the LM7805.




Recommended Article:

Is LM317 better than LM7805?[video+FAQ]

LM258P Low Power Dual Bipolar Op-amps: Description, Features, and Applications

LM317AT-Linear Voltage Regulators 3-TERMINAL ADJ REG



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Parts with Similar Specs

The three parts on the right have similar specifications to ON Semiconductor & LM317T.
Frequently Asked Questions

How does LM317 work?

An LM317 is a voltage regulator that can supply variable output voltage. The working principle of the LM317 is very simple. It uses a voltage divider, formed by using two external resistors connected in series. The output voltage is adjusted by varying the resistor values.

What is a LM317 used for?

The LM317 is commonly used as:
1. A voltage regulator in electronic devices to provide a stable output voltage.
2. A precision current regulator to provide constant current.
3. In designing battery charger circuits and variable power supplies.

What is the maximum input voltage of a LM317?

The maximum input voltage of LM317 is 40 V. The LM317 can operate as long as the difference between its input voltage and the desired output voltage is in the range of 3-40 V.

What is the output voltage of a LM317?

The LM317 can provide an adjustable output voltage between 1.25 V and 37 V. It can supply current up to 1.5 A.
LM317T

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