Fairchild Semiconductor LM317T
| Parameters | |
|---|---|
| Series | - |
| Package / Case | TO-220-3 |
| Mfr | Fairchild Semiconductor |
| Mounting Type | Through Hole |
| Operating Temperature | 0°C ~ 125°C |
| Voltage - Input (Max) | 40V |
| Output Type | Adjustable |
| Current - Output | 1.5A |
| Supplier Device Package | TO-220AB |
| Output Configuration | Positive |
| Control Features | - |
| Voltage - Output (Min/Fixed) | 1.2V |
| Voltage - Output (Max) | 37V |
| Number of Regulators | 1 |
| Protection Features | Over Current, Over Temperature, Short Circuit |
| PSRR | 80dB ~ 65dB (120Hz) |
| Voltage Dropout (Max) | - |
| Package | Bulk |
| Product Status | Obsolete |
| Base Product Number | LM317 |
| Standard Package | 1 |
| ECCN | EAR99 |
| HTSUS | 8542.39.0001 |
Fairchild LM317T Adjustable voltage regulator, Precision power supply IC
The LM317T from Fairchild Semiconductor (now part of ON Semiconductor) is an adjustable positive voltage regulator capable of delivering 1.5A of output current with an output voltage range from 1.25V to 37V. This versatile linear regulator operates with an input voltage range of 3V to 40V, making it suitable for a wide variety of power supply applications. The device features internal current limiting, thermal overload protection, and safe operating area (SOA) protection, ensuring reliable operation under various conditions. Housed in a TO-220 package, the LM317T offers excellent thermal performance and is compatible with through-hole PCB mounting. With its low dropout voltage (typically 2V at full load) and line/load regulation of 0.01%/V, this regulator is ideal for laboratory power supplies, battery chargers, and other precision voltage regulation applications.
The LM317T provides exceptional voltage regulation accuracy (±1% typical) and maintains stable output with only two external resistors required to set the output voltage. It includes built-in thermal shutdown protection to prevent damage from excessive heat and short-circuit protection to safeguard connected components. The regulator features floating operation capability, allowing it to be used in high-voltage applications when combined with external components. Its wide operating temperature range (0°C to +125°C) ensures reliable performance in various environments. Additionally, the device offers low output noise and excellent ripple rejection (80dB typical), making it suitable for sensitive analog circuits and audio applications.
This adjustable regulator is widely used in bench power supplies, battery charging circuits, and voltage reference applications. It serves as an excellent choice for creating custom power supplies for microcontrollers, operational amplifiers, and other electronic components requiring precise voltage levels. The LM317T is commonly employed in LED drivers, motor control circuits, and industrial control systems where adjustable voltage regulation is needed. Its robust design makes it suitable for educational electronics projects, prototyping applications, and repair/maintenance of electronic equipment. The regulator is also frequently used in audio amplifiers and analog signal processing circuits due to its clean power delivery characteristics.
Selection Advantages
Compared to similar adjustable regulators, the LM317T offers unmatched versatility with its wide input voltage range and adjustable output capability. The TO-220 package provides superior thermal performance, allowing for higher power dissipation when mounted on a heatsink. Its simple implementation (requiring only two external resistors and optional capacitors) reduces design complexity and component count. The regulator's proven reliability and decades of field use make it a trusted choice for engineers worldwide. Fairchild Semiconductor's (now ON Semiconductor) strict quality standards ensure consistent performance across production lots. The device's excellent line and load regulation provides stable output under varying input conditions, while its low output noise makes it ideal for sensitive analog applications.
