on November 19th 45

LM317T Voltage Regulator: Alternatives, Pinout, and Datasheet

This article explores the LM317T voltage regulator, a versatile component known for its ability to adjust voltage outputs from 1.2V to 37V. Widely used in a variety of electronic projects, the LM317T combines simplicity and effective performance. Its design supports easy integration to efficiently meet diverse application requirements with precision.

Catalog

What is the LM317T Voltage Regulator?

The LM317T stands out as a highly adaptable voltage regulator encased in a TO-220 package, known for its uncomplicated design and impressive performance in managing positive voltage outputs. It can accommodate currents greater than 1.5A, easing power management using a resistive divider for exact voltage tuning. This capability supports a wide voltage range, reducing the need for multiple fixed regulators. The LM317T is characterized by features that support efficient power regulation. Its proficiency in maintaining a stable output voltage despite variable input conditions underscores its efficiency. When using the LM317T, its thermal overload protection and short-circuit protection, providing consistent performance and resilience even in demanding environments. The LM317T is often integrated into power supply circuits for devices with varied voltage requirements. Its straightforward design allows for easy adjustments and maintenance, offering benefits in educational settings and experimental setups.

LM317T Pin Configuration

Pin No	Pin Name	Description
1	Adjust	This pin adjusts the output voltage
2	Output Voltage (Vout)	The regulated output voltage set by the adjusted pin can be obtained from this pin
3	Input Voltage (Vin)	The input voltage which has to be regulated is given to this pin

LM317T Symbol and Footprint

Features of the LM317T

Adjustable Voltage Range

One striking aspect of the LM317T is its adjustable voltage range from 1.2V to 37V, which caters to applications needing fine-tuned voltage management. This versatility appeals to many electronic applications, reducing design complications.

Current Handling Capability

With support for currents over 1.5A, the LM317T is tailored for high-demand circuits with a focus on maintaining stability across varying power needs. This characteristic contributes to seamless device operation, making it a valued component where power demands are unpredictable.

Precision in Regulation

The LM317T excels in maintaining a tight line and load regulation at 0.1%, minimizing voltage variability that could disrupt or degrade sensitive components.

Versatile Voltage Operation

The floating voltage design of the LM317T enhances circuit layout flexibility, supporting its use in negative voltage scenarios without necessitating complicated configurations. This capability becomes advantageous when multiple regulators are integrated within a single system.

Safeguard Features

Equipped with overcurrent protection, thermal shutdown, and SOA control, the LM317T offers robust safeguards, bolstering system integrity against common threats like short circuits and overheating. Through these features, many create a harmonious blend of innovation and dependability, driving forward product performance and longevity.

LM317T Technical Specifications

Type	Parameter
Lifecycle Status	ACTIVE (Last Updated: 7 months ago)
Contact Plating	Tin
Mounting Type	Through Hole
Number of Pins	3
Manufacturer Package Identifier	0015988_typeA_Rev_T
Packaging	Tube
JESD-609 Code	e3
Moisture Sensitivity Level (MSL)	1 (Unlimited)
ECCN Code	EAR99
Number of Functions	1
Base Part Number	LM317
Number of Outputs	1
Output Voltage	37V
Factory Lead Time	24 Weeks
Mount	Through Hole
Package / Case	TO-220-3
Weight	2.299807g
Operating Temperature	0°C~125°C
Tolerance	5%
Part Status	Active
Number of Terminations	3
Terminal Position	SINGLE
Terminal Pitch	2.54mm
Pin Count	3
Voltage - Input (Max)	40V
Output Type	Adjustable
Max Output Current	1.5A
Max Output Voltage	37V
Min Input Voltage	4.2V
PSRR	80dB ~ 85dB (120Hz)
Min Output Voltage	1.2V
Height	9.15mm
Width	4.6mm
Radiation Hardening	No
Lead Free	Lead Free
Output Configuration	Positive
Number of Regulators	1
Protection Features	Over Current, Over Temperature
Reference Voltage	1.25V
Power Supply Rejection Ratio (PSRR)	80dB
Length	10.4mm
REACH SVHC	No SVHC
RoHS Status	ROHS3 Compliant

LM317T Schematic Diagram

Alternatives for LM317T

Part Number	Description	Manufacturer
LM317KC	3/4 Pin 1.5A Adjustable Positive Voltage Regulator 3-TO-220 0 to 125	Texas Instruments
LM317T#PBF	IC VREG 1.2 V-37 V ADJUSTABLE POSITIVE REGULATOR, PSFM3, PLASTIC, TO-220, 3 PIN, Adjustable Positive Single Output Standard Regulator	Linear Technology
LM317T/NOPB	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
LM317T2	1.2 V-37V ADJUSTABLE POSITIVE REGULATOR, PSFM3, PLASTIC, TO-220, 3 PIN	ON Semiconductor

Additional LM317T Equivalents include: LM317EMP, LM317AEMP, LM317LIDR, LM317LMX, and others.

Where and How to Use the LM317?

Versatile Power Control with Variable Voltage Supplies

The LM317 finds extensive use in variable voltage power supply applications due to its ability to adjust output voltage levels. In educational environments and electronics laboratories, it supports the development and testing of diverse circuits. With a flexible output range from 1.25V to 37V, enjoy a broad spectrum of possibilities.

Simplified Overcurrent Solutions with Current Limiters

For applications requiring current limitation, the LM317 delivers an effective and straightforward approach. This characteristic proves beneficial in battery chargers and power management systems where safeguarding against overcurrent is needed. By inserting a resistor in series with the output, the regulator ensures the current is maintained within secure bounds, preserving both the power source and connected devices. Such a method remarkably boosts device longevity and dependability.

Precise Control in Motor Controller Applications

The adaptability of the LM317 extends its utility to motor controllers, where it regulates voltage for DC motors in robotics and automation settings, offering precise motor speed control. This regulator facilitates smooth transitions in acceleration and deceleration, which is particularly used for applications demanding precise movements, such as in robotic arms or CNC machinery. Its efficiency in providing stable motor function under changing load conditions accentuates its practicality in varied industrial scenarios.

Evaluating Dropout Voltage Considerations

Despite its robust features, the LM317’s 2.5V dropout voltage requires careful evaluation. This aspect potentially affects its application in low voltage scenarios where the input-to-output differential must be minimal. You need to verify that the input voltage surpasses the desired output by at least this dropout value to ensure effective operation. In cases where dropout voltage can limit functionality, considering alternative low-dropout (LDO) regulators could be more appropriate, balancing technical necessities with creative solutions.

Enhanced Role in Consumer Electronics

The LM317 finds widespread use across various consumer electronics such as PCs and DVD players. Its reliability and simplicity endear it to power regulation tasks, extending from delivering power to logic circuits to stabilizing voltage for sensitive components. This versatility highlights the role of the LM317 in boosting device performance and reliability, contributing to the uninterrupted function of household devices.

LM317 Circuitry Applications

Voltage Regulation

The LM317’s adjustable output capability allows it to maintain consistent voltage output despite fluctuations in input voltage or load conditions, ensuring sensitive electronic devices operate reliably. Voltage regulation plays a role in applications like battery chargers and portable devices. A stable voltage level can extend battery life and enhance device performance.

Current Limiting

Current limiting is key to preventing overcurrent conditions that could harm circuit components. By automatically adjusting to manage current flow, it serves as an efficient shield against unintended high current scenarios. In practical settings, it’s required in circuits that incorporate a variety of components with different current ratings, maintaining safe and optimal operation without overheating or failure.

Polarity Protection

Polarity protection addresses common issues such as incorrect power supply connections often encountered during product prototyping or routine adjustments. Circuit design and maintenance shows the value of polarity protection in ensuring long-term durability and reliable performance under varying operational circumstances.

Package for LM317T

TO-220 (single gauge) Package Information

TO-220 (single gauge) Mechanical Data

LM317T Manufacturer Information

STMicroelectronics stands prominently within the semiconductor industry, enriching the development and creativity of System on Chip (SoC) technology. The company's impact stretches across various microelectronics applications, influencing global industries and fostering the blending of diverse technologies. STMicroelectronics is renowned for its progress in SoC solutions, merging various functions onto a single chip. This integration is aimed at enhancing performance, lowering power usage, and shrinking the system's total size. The commitment of STMicroelectronics to innovation propels its exploration of new areas in microelectronics, encouraging an ongoing development of abilities. Their research and development initiatives not only aim to enhance current technologies but also to formulate new models that tackle modern issues like sustainable development and energy conservation.

Datasheet PDF

LM317T Datasheets:

LM217, LM317.pdf