Overview
The LM317AT, produced by Texas Instruments, is an adjustable three-terminal positive-voltage regulator. This device is capable of supplying up to 1.5 A of current over an output-voltage range of 1.25 V to 37 V. It is known for its high accuracy and robust protection features, making it versatile for various electronic applications. The LM317AT requires only two external resistors to set the desired output voltage, and it includes current limiting, thermal overload protection, and safe operating area protection.
Key Specifications
| Parameter | Value | Unit |
|---|---|---|
| Input Voltage Range | 4.25 - 40 | V |
| Output Voltage Range | 1.25 - 37 | V |
| Maximum Continuous Drain Current | 1.5 | A |
| Load Regulation Accuracy | 1% | % |
| PSRR (120 Hz) | 80 dB | dB |
| Operating Temperature Range | -40 to 125 | °C |
| Thermal Resistance (θJA) | 23.3 °C/W (TO-220) | °C/W |
| Quiescent Current (Iq) | 5 mA (typical) | mA |
| Dropout Voltage (Vdo) | 2.25 V (typical) | V |
| Package/Case | TO-220-3 |
Key Features
- Adjustable Output Voltage: The LM317AT allows for precise adjustment of the output voltage using two external resistors.
- High Accuracy: Offers 1% output-voltage accuracy, ensuring reliable and stable voltage regulation.
- Robust Protection: Includes over-current, thermal-overload protection, and safe operating area protection. These protection features remain functional even if the adjustment terminal is disconnected.
- Low Output Impedance: The NPN Darlington output topology provides naturally low output impedance, and an optional output capacitor can be added to improve transient response.
- Programmable Feedback: Allows for easy programming of output voltage or current using an op amp with a 1.25-V offset input at the ADJUST terminal.
Applications
- Programmable Output Regulation: Suitable for applications requiring adjustable voltage levels, such as in ATCA solutions, DLP systems, and optical networking.
- Local On-Card Regulation: Can be used for local voltage regulation on circuit boards, providing a stable and adjustable voltage source.
- Battery Chargers: The LM317AT can be used in battery charger applications to maintain constant voltage or constant current modes depending on the battery's charge level.
- Desktop PCs and DVR/DVS Systems: Applicable in various consumer electronics and industrial systems requiring reliable voltage regulation.
Q & A
- What is the maximum output current of the LM317AT?
The LM317AT can supply up to 1.5 A of current.
- What is the output voltage range of the LM317AT?
The output voltage range is from 1.25 V to 37 V.
- What is the typical load regulation accuracy of the LM317AT?
The load regulation accuracy is typically 1%.
- Does the LM317AT have built-in protection features?
Yes, it includes over-current, thermal-overload protection, and safe operating area protection.
- What is the recommended operating temperature range for the LM317AT?
The operating temperature range is from -40°C to 125°C.
- How do you set the output voltage of the LM317AT?
The output voltage is set using two external resistors connected to the ADJUST and OUTPUT terminals.
- Can the LM317AT be used as a current regulator?
Yes, by connecting a fixed resistor between the ADJUST and OUTPUT terminals, it can function as a precision current regulator.
- What is the typical quiescent current of the LM317AT?
The typical quiescent current is 5 mA.
- What is the dropout voltage of the LM317AT?
The typical dropout voltage is 2.25 V.
- Is the LM317AT RoHS compliant?
Yes, the LM317AT is RoHS compliant.
