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Product details

Parameters

Output options Adjustable Output Iout (Max) (A) 1.5 Vin (Max) (V) 40 Vin (Min) (V) 3 Vout (Max) (V) 37 Vout (Min) (V) 1.2 Noise (uVrms) 38 Iq (Typ) (mA) 5 Thermal resistance θJA (°C/W) 24 Approx. price (US$) 0.54 | 1ku Load capacitance (Min) (µF) 0 Rating Catalog Regulated outputs (#) 1 Features Accuracy (%) 5 PSRR @ 100 KHz (dB) 40 Dropout voltage (Vdo) (Typ) (mV) 2250 Operating temperature range (C) -40 to 125 open-in-new Find other Linear regulators (LDO)

Package | Pins | Size

SOT-223 (DCY) 4 46 mm² 6.5 x 7 TO-220 (NDE) 3 47 mm² 10.16 x 4.58 TO-252 (NDP) 3 40 mm² 7.3 x 6.58 TO-CAN (NDT) 3 92 mm² 10.03 x 9.14 open-in-new Find other Linear regulators (LDO)

Features

  • Typical 0.005%/V Line Regulation
  • 1% Output Voltage Tolerance
  • 1.5-A Output Current
  • Adjustable Output Down to 1.25 V
  • Current Limit Constant with Temperature
  • 80-dB Ripple Rejection
  • Short-Circuit Protected Output
  • −40°C to 125°C Operating Temperature Range
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Description

The LM317A adjustable 3-terminal, positive-voltage regulators are capable of supplying current in excess of 1.5 A over a 1.25-V to 37-V output range and provide 1% output-voltage accuracy. The LM317A device is available in an SOT-223 package, which makes it ideal for space-constrained applications that require high-performance regulation. The device is exceptionally easy to use and requires only two external resistors to set the output voltage. Both line regulation and load regulation are better achieved with the LM317A device than with standard fixed regulators.

The LM317A offers full overload protection such as current limit, thermal-overload protection, and safe-area protection. All overload protection circuitry remains fully functional even if the adjustment terminal is disconnected.

Typically, 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 that are difficult to achieve with standard 3-terminal regulators.

Because the LM317A regulator is and detects 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. Exceeding the maximum input-to-output deferential will result in short-circuiting the output.

By connecting a fixed resistor between the adjustment pin and output, the LM317A can be also 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 1.25 V where most loads draw little current.

For applications requiring greater output current, see data sheets for LM150 series (3A), SNVS772, and LM138 series (5A), SNVS771. For the negative complement, see LM137 (SNVS778) series data sheet.

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Technical documentation

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No results found. Please clear your search and try again. View all 18
Type Title Date
* Datasheet LM317A 1% Accurate Three-Terminal Adjustable Regulator datasheet Oct. 30, 2015
Application notes A Topical Index of TI LDO Application Notes (Rev. F) Jun. 27, 2019
Technical articles LDO basics: capacitor vs. capacitance Aug. 01, 2018
Technical articles LDO Basics: Preventing reverse current Jul. 25, 2018
Technical articles LDO basics: introduction to quiescent current Jun. 20, 2018
Technical articles LDO basics: noise – part 1 Jun. 14, 2017
User guides LM317A-337N-EVM User's Guide Jan. 21, 2016
Application notes AN-1028 Maximum Power Enhancement Techniques for Power Packages (Rev. B) May 06, 2013
Application notes AN-103 LM340 Series Three Terminal Positive Regulators (Rev. A) May 06, 2013
Application notes AN-1148 Linear Regulators: Theory of Operation and Compensation (Rev. B) May 06, 2013
Application notes AN-181 3-Terminal Regulator is Adjustable (Rev. B) May 05, 2013
Application notes AN-182 Improving Power Supply Reliability with IC Power Regulators (Rev. B) May 05, 2013
Application notes Method For Cal Output Voltage Tolerances in Adj Regs (Rev. A) May 05, 2013
More literature Die D/S LM317A MWC 3-Terminal Adj Regulator Sep. 20, 2012
Application notes Packaging Limits Range of Linear Regulators May 08, 2010
Application notes Digital Designer's Guide to Linear Voltage Regulators & Thermal Mgmt (LDO) (Rev. A) Jun. 04, 2008
Application notes Adjustable 3-Terminal Regulator for Low-Cost Battery Charging Systems Oct. 03, 2002
Application notes Understanding the Terms and Definitions of LDO Voltage Regulators Oct. 21, 1999

Design & development

For additional terms or required resources, click any title below to view the detail page where available.

Hardware development

EVALUATION BOARDS Download
document-generic User guide
$29.00
Description

The LM317A-337N-EVM demonstrates canonical application of the LM317A adjustable regulator and its negative complement, the LM337-N. The evaluation module (EVM) is assesmbled with the SOT-223 package option for each device, supplying up to 1 A of load current. The EVM is designed for easy (...)

Features
  • Output adjustable from 1.2 V to 37 V for LM317A and –1.2 V to –37 V for LM337-N
  • 1-A load current with 1.5-A option
  • Heat sink space provided for TO-220
  • Large capacitor footprint space for customer selection

Design tools & simulation

SIMULATION MODELS Download
SNVMAP0A.ZIP (54 KB) - PSpice Model
SIMULATION MODELS Download
SNVMAP1A.ZIP (2 KB) - PSpice Model

CAD/CAE symbols

Package Pins Download
SOT-223 (DCY) 4 View options
TO (NDT) 3 View options
TO-220 (NDE) 3 View options
TO-252 (NDP) 3 View options

Ordering & quality

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