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LM317T Voltage Regulator: Pinout, Datasheet, Circuit [Video]

  • Contents

There have been many articles about LM317, today we will talk about LM317T separately. This blog will cover not only its pinout , features, applications but also its CAD models, functional equivalents and some useful circuits, the datasheet is at the bottom of the page as always.

 

The LM317T belongs to a sort of an adjustable three terminal positive voltage regulator, designed to supply more than 1.5A of load current with an output voltage adjustable over a 1.2V to 3.7V range. The nominal output voltage is selected by means of a resistive divider, making the device exceptionally easy to use and eliminating the stocking of many constant regulators. Apart from using it as a variable voltage regulator, LM317T IC can also be used as a constant voltage regulator, current limiter, Battery charger, AC voltage regulator and even as an adjustable current regulator.

 

Down below is a video about how LM317T functions in a circuit.

 

Adjustable Voltage Regulator LM317T functional demo


Catalog

LM317T Pinout

LM317T Features

LM317T Schematic Circuit

LM317T Specifications

LM317T CAD Models

LM317T Applications

LM317T Package

LM317T Circuit

LM317T Functional Equivalents

LM317T Popularity by Region

LM317T Market Price Analysis

LM317T Manufacturer

Component Datasheet


LM317T Pinout

LM317T Pinout

Pin Number

Pin Name

Description

Pin1

Adjust

This pin adjusts the output voltage

Pin2

Output Voltage (Vout)

The regulated output voltage set by the adjust pin can be obtained from this pin

Pin3

Input Voltage (Vin)

The input voltage which has to be regulated is given to this pin


LM317T Features

According to LM317T datasheet, it features:

  • Output voltage range: 1.2 to 37 V 

  • Output current in excess of 1.5 A

  • 0.1% line and load regulation 

  • Current Limit Constant with Temperature

  • 100% Electrical Burn–In 

  • Eliminates the Need to Stock Many Voltages

  • 80dB Ripple Rejection


LM317T Schematic Circuit

Circuit schematic can help us to understand better about how a component or chip is used and worked in circuits. It’s a reference to make them work in an actual circuit. The following LM317T circuit schematic is a sample for reference.

LM317T Schematic Circuit


LM317T Specifications

Product Attribute

Attribute Value

Manufacturer:

STMicroelectronics

Product Category:

Linear Voltage Regulators

Mounting Style:

Through Hole

Package / Case:

TO-220-3

Number of Outputs:

1 Output

Polarity:

Positive

Output Voltage:

1.2 V to 37 V

Output Current:

1.5 A

Output Type:

Adjustable

Input Voltage MAX:

40 V

Input Voltage MIN:

4.2 V

Minimum Operating Temperature:

0 C

Maximum Operating Temperature:

+ 125 C

Load Regulation:

0.5 %

Line Regulation:

0.04 %/V

Series:

LM317

Packaging:

Tube

Height:

9.15 mm

Length:

10.4 mm

Operating Temperature Range:

0 C to + 125 C

Width:

4.6 mm

Brand:

STMicroelectronics

PSRR / Ripple Rejection - Typ:

80 dB

Product Type:

Linear Voltage Regulators

Factory Pack Quantity:

1000

Subcategory:

PMIC - Power Management ICs

Unit Weight:

0.081130 oz


LM317T CAD Models

LM317T Part Symbol

LM317T Footprint

LM317T 3D Model


LM317T Applications

LM317T voltage regulator is used in a wide range in circuits, the most common applications:

  • Used for Positive voltage regulations

  • Used in motor control circuits

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

  • Variable power supply

  • Current limiting circuits

  • Reverse polarity circuits


LM317T Package

LM317T Mechanical Data

LM317T Package


LM317T Circuit

This is how a LM317T regulator would look when connected to a circuit so that it supplies a constant DC voltage output.

LM317T Circuit

In this circuit, we add a DC voltage supply to the VIN pin of the regulator. This is the pin which, again, receives incoming voltage which the chip will then regulate down. The voltage which enters this pin must be larger than the voltage it is feeding out. Remember, voltage regulators are just devices that regulate voltage down to a certain level. They do not and cannot create voltage on their own. Therefore, in order to a get a voltage, VOUT, VIN must be greater than VOUT. In this circuit, we want a regulated 5VDC as output. Therefore, VIN must be greater than 5 volts. Generally, with regulators, unless they are low drop out regulators, you want the input voltage to be about 2 volts higher. So therefore, since we want 5 volts as output, we will feed into this regulator 7 volts.

 

Now that we've dealt with the input pin, we must now deal with the adjustable pin (Adj). This is the pin which allows us to adjust the voltage to the level we want. Since we want 5 volts to be output, we must calculate which value of R2 will yield an output of 5 volts. Using the formula for the output voltage, VOUT= 1.25V (1 + R2/R1). Being that R1=240Ω, our equation is now 5V= 1.25V (1 + R2/240Ω), so R2=720Ω. So with R2 being a value of 720Ω, the LM317 will output 5V if fed an input voltage greater than 5 volts. If you need to calculate output voltages or which resistor R2 value you would need for a circuit, see LM317 Calculator online. This can help you find the exact resistor value needed for a circuit.

 

The last pin of the LM317 is the output pin. This is where the regulated voltage (in this case, 5 volts) will come out. To feed a circuit the regulated 5 volts, we just connect it to the output pin.


LM317T Functional Equivalents

Part Number

Description

Manufacturer

LM317T#PBF

POWER CIRCUITS

IC VREG 1.2 V-37 V ADJUSTABLE POSITIVE REGULATOR, PSFM3, PLASTIC, TO-220, 3 PIN, Adjustable Positive Single Output Standard Regulator

Linear Technology

LM317T2

POWER CIRCUITS

1.2 V-37V ADJUSTABLE POSITIVE REGULATOR, PSFM3, PLASTIC, TO-220, 3 PIN

Motorola Mobility LLC

LM317KCS

POWER CIRCUITS

1.5-A, 40-V, adjustable linear voltage regulator 3-TO-220 0 to 125

Texas Instruments

LM317T/NOPB

POWER CIRCUITS

IC VREG 1.2 V-37 V ADJUSTABLE POSITIVE REGULATOR, PSFM3, ROHS COMPLIANT, PLASTIC, TO-220, 3 PIN, Adjustable Positive Single Output Standard Regulator

National Semiconductor Corporation

LM317KC

POWER CIRCUITS

3/4 Pin 1.5A Adjustable Positive Voltage Regulator 3-TO-220 0 to 125

Texas Instruments

LM317P

POWER CIRCUITS

1.2 V to 37 V adjustable voltage regulators

STMicroelectronics

LM317BT4

POWER CIRCUITS

1.2 V-37V ADJUSTABLE POSITIVE REGULATOR, PSFM3, PLASTIC, TO-220, 3 PIN

Motorola Mobility LLC

LM317BT

POWER CIRCUITS

1.2 V-37V ADJUSTABLE POSITIVE REGULATOR, PSFM3, PLASTIC, TO-220, 3 PIN

ON Semiconductor

LM317BTG

POWER CIRCUITS

Linear Voltage Regulator, 1.5 A, High PSRR, Adjustable, Positive TJ = -40° to +125°C, TO-220, SINGLE GAUGE, 3-LEAD, 50-TUBE

ON Semiconductor

LM317KCE3

POWER CIRCUITS

3/4 Pin 1.5A Adjustable Positive Voltage Regulator 3-TO-220 0 to 125

Texas Instruments


LM317T Popularity by Region

LM317T Popularity by Region


LM317T Market Price Analysis

LM317T Market Price Analysis


LM317T Manufacturer

STMicroelectronics (SGS-THOMSON, ST) group was established in 1987 by the merger of SGS Microelectronics in Italy and Thomson Semiconductor in France. In May 1998, SGS-THOMSON Microelectronics changed its company name to STMicroelectronics Co., Ltd. STMicroelectronics is one of the world’s largest semiconductor companies. It aims to be the market leader in multimedia application integration and power solutions. STMicroelectronics has the world’s most powerful product lineup, including dedicated products with high intellectual property rights. Products, there are also innovative products in many fields, such as discrete devices, high-performance microcontrollers, security smart card chips, and micro-electromechanical systems (MEMS) devices.


Component Datasheet

LM317T Datasheet

 

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