LM 317
The LM317 is a widely used adjustable voltage regulator integrated circuit (IC) that was developed by Robert C. Dobkin and Robert J. Widlar at National Semiconductor (now part of Texas Instruments). Here is a brief history of the LM317:
Development Phase: The LM317 was introduced in 1972 as a linear voltage regulator IC. It was designed to be an improved and adjustable version of the older LM117, which was a fixed output regulator.
Creators: Robert C. Dobkin and Robert J. Widlar are credited with the development of the LM317. Dobkin was responsible for the architecture and the initial design of the LM317, while Widlar provided crucial insight and guidance during the development process.
Purpose: The LM317 was designed to provide a variable output voltage that could be set by an external resistor network, allowing for flexibility in voltage regulation applications. This made it a versatile choice for various electronic circuits where a stable and adjustable voltage source was needed.
Advantages Over Earlier Regulators: One of the key advantages of the LM317 was its ability to provide a continuous range of output voltages from 1.25 volts up to its maximum rated voltage (usually around 37 volts), making it suitable for a wide range of applications.
Popularity and Applications: Due to its versatility, simplicity, and reliability, the LM317 quickly gained popularity among electronics enthusiasts, hobbyists, and professionals alike. It found widespread use in power supplies, battery chargers, audio equipment, and various other electronic devices.
Legacy and Continued Use: Even decades after its introduction, the LM317 remains a popular choice for voltage regulation tasks, particularly in analog circuits. Its simplicity, low cost, and ease of use have contributed to its longevity in the electronics industry.
Manufacturing and Availability: The LM317 has been manufactured by various semiconductor companies over the years, with Texas Instruments (TI) being one of the major producers after their acquisition of National Semiconductor. The IC is widely available from electronics suppliers and is still used extensively in educational, hobbyist, and professional projects.
In summary, the LM317 is an enduring component in electronics design, owing to its innovative design and robust functionality. Its introduction marked a significant advancement in the field of voltage regulation, offering engineers and hobbyists a versatile and efficient solution for a wide range of applications.
+----------------------------------------------------------------------------+
| |
| |
| |
| |
| |
| |
| x x xxxx xxxxxxxx xxxxxxxxxx |
| x xxx xxxxx x xx |
| x x xx xx xxx x x |
| x x xxxxx xx xxxxxxxxx x xx |
| x x x xx x x x |
| x x xx x x xxxxxxx |
| x x xx x x x |
| x x xx x x x |
| x x xx x x xx |
| xxxxxxx x xx xxxxxxxxxx x x |
| |
| |
| |
| |
| |
| |
| |
| |
| |
+----------+--------+-------------+--------+-----------+--------+------------+
| | | | | |
| | | | | |
| | | | | |
| | | | | |
| | | | | |
| | | | | |
| | | | | |
| | | | | |
| | | | | |
+--+--+--+ +--+--+--+ +--+--+--+
| | | | | |
| | | | | |
| | | | | |
| | | | | |
| | | | | |
| | | | | |
| | | | | |
| | | | | |
+--+ +--+ +--+
The LM317 is widely used for several key reasons:
Adjustable Output: One of the primary advantages of the LM317 is its ability to provide a continuously adjustable output voltage. By connecting external resistors, the output voltage can be set to any desired value within its specified range (typically 1.25V to 37V). This flexibility makes it suitable for a wide variety of applications where specific voltage levels are required.
Simple Design: The LM317 is relatively easy to use and requires minimal external components to function effectively. Typically, only a couple of external resistors are needed to set the output voltage, simplifying the overall circuit design and reducing component count.
Stable and Reliable: The LM317 offers good output voltage regulation and line regulation characteristics. It can maintain a stable output voltage even with variations in load currents and input voltages, which is essential for many electronic devices.
Low Dropout Voltage: The LM317 has a low dropout voltage compared to many other linear regulators. This means it can regulate the output voltage efficiently even when the input voltage is only slightly higher than the desired output voltage, minimizing power dissipation and maximizing efficiency.
Wide Operating Range: The LM317 can operate over a wide range of input voltages (up to 40V) and output currents (up to 1.5A with adequate heat sinking). This versatility makes it suitable for various power supply applications.
Cost-Effective: The LM317 is a cost-effective solution for voltage regulation, making it accessible for hobbyists, students, and small-scale projects. It provides excellent performance for its price point, making it a popular choice among electronics enthusiasts.
Availability and Documentation: Being a widely used and established component, the LM317 is well-documented in datasheets, application notes, and electronics resources. This availability of information makes it easier for engineers and designers to integrate the LM317 into their circuits confidently.
Versatility: The LM317 can be used in a wide range of applications including power supplies, battery chargers, LED drivers, audio amplifiers, and more. Its versatility and adaptability to different circuit requirements contribute to its widespread adoption.
Overall, the combination of adjustable output, simplicity, reliability, performance, and affordability has made the LM317 a go-to choice for voltage regulation in countless electronic projects and applications. Its enduring popularity over several decades is a testament to its effectiveness and usefulness in the field of electronics.