LM117/LM317A/LM317 3-Terminal Adjustable Regulator - Datasheet Overview

Nov 2, 2026

LM117/LM317A/LM317 is a 3-terminal adjustable positive-voltage regulator series designed to provide over 1.5A output current across a 1.2V to 37V range. The devices use only two external resistors to set the output voltage and offer better line and load regulation than standard fixed regulators. Built-in current limit, thermal overload protection, and safe-area protection support robust overload behavior even when the adjustment terminal is disconnected. Optional input/output capacitor guidance and methods for high ripple rejection are included, along with package options and ratings.

LanguageEnglish

CategoryTechnology

FormatPDF

Pages37

Reading Time1 h 33 min

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Features

Description

Typical Applications

Adjustable Regulator Range

Package Options

TO-3, TO-220, TO-263, SOT-223, TO-39, LCC, TO-252

Connection Diagrams

Absolute Maximum Ratings

Operating Temperature Range

LM117, LM317-N [www.ti.com](www.ti.com) SNVS774L –MAY 2004–REVISED FEBRUARY 2011 LM117/LM317A/LM317 3-Terminal Adjustable Regulator Check for Samples: LM117, LM317-N FEATURES • Guaranteed 1% output voltage tolerance (LM317A) • Guaranteed max. 0.01%/V line regulation (LM317A) • Guaranteed max. 0.3% load regulation (LM117) • Guaranteed 1.5A output current • Adjustable output down to 1.2V • Current limit constant with temperature • P+ Product Enhancement tested • 80 dB ripple rejection • Output is short-circuit protected DESCRIPTION The LM117 series of adjustable 3-terminal positive voltage regulators is capable of supplying in excess of 1.5A over a 1.2V to 37V output range. They are exceptionally easy to use and require only two external resistors to set the output voltage. Further, both line and load regulation are better than standard fixed regulators. Also, the LM117 is packaged in standard transistor packages which are easily mounted and handled. In addition to higher performance than fixed regulators, the LM117 series offers full overload protection available only in IC's. Included on the chip are current limit, thermal overload protection and safe area protection. All overload protection circuitry remains fully functional even if the adjustment terminal is disconnected. Normally, no capacitors are needed unless the device is situated more than 6 inches from the input filter capacitors in which case an input bypass is needed. An optional output capacitor can be added to improve transient response. The adjustment terminal can be bypassed to achieve very high ripple rejection ratios which are difficult to achieve with standard 3-terminal regulators. Besides replacing fixed regulators, the LM117 is useful in a wide variety of other applications. Since the regulator is “floating” and sees only the input-to-output differential voltage, supplies of several hundred volts can be regulated as long as the maximum input to output differential is not exceeded, i.e. , avoid short-circuiting the output. Also, it makes an especially simple adjustable switching regulator, a programmable output regulator, or by connecting a fixed resistor between the adjustment pin and output, the LM117 can be used as a precision current regulator. Supplies with electronic shutdown can be achieved by clamping the adjustment terminal to ground which programs the output to 1.2V where most loads draw little current. For applications requiring greater output current, see LM150 series (3A) and LM138 series (5A) data sheets. For the negative complement, see LM137 series data sheet. Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. All trademarks are the property of their respective owners. PRODProduUctCsTcIONonforDATAm to sinformapecificiontioniss cpurrerenthteasteof prmsulifcathtnTax. Copyright © 2004–2011, Texas Instruments Incorporated Instruments standard warranty. Production processing does not necessarily include testing of all parameters. LM117, LM317-N SNVS774L –MAY 2004–REVISED FEBRUARY 2011 [www.ti.com](www.ti.com) Typical Applications Figure 1. 1.2V–25V Adjustable Regulator Full output current not available at high input-output voltages *Needed if device is more than 6 inches from filter capacitors. †Optional—improves transient response. Output capacitors in the range of 1μF to 1000μF of aluminum or tantalum electrolytic are commonly used to provide improved output impedance and rejection of transients. Table 1. LM117/LM317A/LM317 Package Options | Part
Number | Suffix | Package | Output
Current | | --- | --- | --- | --- | | LM117, LM317 | K | TO-3 | 1.5A | | LM317A, LM317 | T | TO-220 | 1.5A | | LM317 | S | TO-263 | 1.5A | | LM317A, LM317 | EMP | SOT-223 | 1.0A | | LM117, LM317A, LM317 | H | TO-39 | 0.5A | |

FAQs

What output range and current can the LM117 series deliver?

The LM117 series supports a 1.2V to 37V adjustable output range and supplies in excess of 1.5A output current.

How is the output voltage set for LM117/LM317A/LM317?

Only two external resistors are required to set the output voltage.

What protections are built into the LM117 series?

On-chip circuitry includes current limit, thermal overload protection, and safe area protection; overload protection remains functional even if the adjustment terminal is disconnected.

Nov 2, 2026

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