Datasheet LM317 (Texas Instruments)

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LM317
SLVS044Z – SEPTEMBER 1997 – REVISED APRIL 2025
LM317 3-Pin Adjustable Regulator 1 Features 3 Description
• Output voltage range: The LM317 is an adjustable three-pin, positive-voltage – Adjustable: 1.25V to 37V regulator capable of supplying more than 1.5A over • Output current: 1.5A an output voltage range of 1.25V to 37V. The device • Line regulation: 0.01%/V (typ) requires only two external resistors to set the output • Load regulation: 0.1% (typ) voltage. The device features a typical line regulation • Internal short-circuit current limiting of 0.01% and typical load regulation of 0.1%. The • Thermal overload protection LM317 includes current limiting, thermal overload • Output safe-area compensation (new chip) protection, and safe operating area protection. • PSRR: 80dB at 120Hz for C Overload protection remains functional even if the ADJ = 10μF (new chip) • Packages: ADJUST pin is disconnected. – 4-pin, SOT-223 (DCY) Typically, no capacitors are needed unless the device – 3-pin, TO-263 (KTT) is situated more than 6 inches from the input filter – 3-pin, TO-220 (KCS, KCT), legacy chip capacitors. In that case, an input bypass is needed.
2 Applications
Add an optional output capacitor to improve transient response. Bypass the adjustment pin to achieve very • Multifunction printers high ripple rejection ratios that are difficult to achieve • AC drive power stage modules with standard 3-pin regulators. • Electricity meters • Servo drive control modules
Package Information
• Merchant network and server PSU
PART NUMBER PACKAGE
(1)
PACKAGE SIZE
(2) DCY (SOT-223, 4) 6.5mm × 7mm KTT (TO-263, 3) 10.16mm × 15.24mm LM317 LM317 KCS, KCT (TO-220, 3) VIN 28V (3) 10.16mm × 4.55mm V †† OUT VIN VOUT ADJ (1) For more information, see the Mechanical, Packaging, and R1 Orderable Information. 240 (2) The package size (length × width) is a nominal value and + includes pins, where applicable. C1* C2† (3) Legacy chip. 0.1 F 1 F R2 5k
RS LM317 0.2
W GND
V INPUT OUTPUT I
*Needed if the device is more than 6 inches from filter
R1 ADJUST
capacitors.
240
W †Optional, improves transient response. ††See Equation 1.
R2 2.4 k
W R V 2 OUT  =  1.25V  ×   1  +  R   +  I 1 ADJ ×   R2 (1)
Battery-Charger Circuit Typical Application
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications, intellectual property matters and other important disclaimers. PRODUCTION DATA. Document Outline 1 Features 2 Applications 3 Description Table of Contents 4 Device Comparison Table 5 Pin Configuration and Functions 6 Specifications 6.1 Absolute Maximum Ratings 6.2 ESD Ratings 6.3 Recommended Operating Conditions 6.4 Thermal Information (Legacy Chip) 6.5 Thermal Information (New Chip) 6.6 Electrical Characteristics 6.7 Typical Characteristics 7 Detailed Description 7.1 Overview 7.2 Functional Block Diagram 7.3 Feature Description 7.3.1 NPN Darlington Output Drive 7.3.2 Overload Block 7.3.3 Programmable Feedback 7.4 Device Functional Modes 7.4.1 Normal Operation 7.4.2 Operation With Low Input Voltage 7.4.3 Operation at Light Loads 7.4.4 Operation In Self Protection 8 Application and Implementation 8.1 Application Information 8.2 Typical Application 8.2.1 Design Requirements 8.2.2 Detailed Design Procedure 8.2.3 Application Curves 8.3 System Examples 8.3.1 0V to 30V Regulator Circuit 8.3.2 Adjustable Regulator Circuit With Improved Ripple Rejection 8.3.3 Precision Current-Limiter Circuit 8.3.4 Tracking Preregulator Circuit 8.3.5 1.25V to 20V Regulator Circuit With Minimum Program Current 8.3.6 Battery-Charger Circuit 8.3.7 50mA, Constant-Current, Battery-Charger Circuit 8.3.8 Slow Turn-On 15V Regulator Circuit 8.3.9 AC Voltage-Regulator Circuit 8.3.10 Current-Limited 6V Charger Circuit 8.3.11 Adjustable 4A Regulator Circuit 8.3.12 High-Current Adjustable Regulator Circuit 8.4 Power Supply Recommendations 8.5 Layout 8.5.1 Layout Guidelines 8.5.1.1 Thermal Considerations 8.5.1.1.1 Heat Sink Requirements 8.5.1.1.2 Heat Sinking Surface-Mount Packages 8.5.1.1.2.1 Heatsinking the SOT-223 (DCY) Package 8.5.1.1.2.2 Heat Sinking the TO-263 (KTT) Package 8.5.2 Layout Examples 9 Device and Documentation Support 9.1 Device Support 9.1.1 Device Nomenclature 9.2 Receiving Notification of Documentation Updates 9.3 Support Resources 9.4 Trademarks 9.5 Electrostatic Discharge Caution 9.6 Glossary 10 Revision History 11 Mechanical, Packaging, and Orderable Information