LM317A

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1.5-A, 40-V, adjustable linear voltage regulator with high-accuracy

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Data sheet

document-pdfAcrobat LM317A 1% Accurate 1.5A Adjustable Voltage Regulator datasheet (Rev. A) PDF | HTML

LM317A

ACTIVE

Data sheet

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Product details

Output options

Adjustable Output, Fixed Output

Iout (max) (A)

1.5

Vin (max) (V)

40

Vin (min) (V)

3

Vout (max) (V)

37

Vout (min) (V)

1.2

Fixed output options (V)

37

Rating

Catalog, Military

Noise (µVrms)

38

PSRR at 100 KHz (dB)

40

Iq (typ) (mA)

5

Thermal resistance θJA (°C/W)

24

Load capacitance (min) (µF)

0

Regulated outputs (#)

1

Accuracy (%)

5

Dropout voltage (Vdo) (typ) (mV)

2250

Operating temperature range (°C)

-40 to 125

Output options

Adjustable Output, Fixed Output

Iout (max) (A)

1.5

Vin (max) (V)

40

Vin (min) (V)

3

Vout (max) (V)

37

Vout (min) (V)

1.2

Fixed output options (V)

37

Rating

Catalog, Military

Noise (µVrms)

38

PSRR at 100 KHz (dB)

40

Iq (typ) (mA)

5

Thermal resistance θJA (°C/W)

24

Load capacitance (min) (µF)

0

Regulated outputs (#)

1

Accuracy (%)

5

Dropout voltage (Vdo) (typ) (mV)

2250

Operating temperature range (°C)

-40 to 125

SOT-223 (DCY)

4

45.5 mm² 6.5 x 7

TO-220 (NDE)

3

46.5328 mm² 10.16 x 4.58

TO-252 (NDP)

3

65.2078 mm² 6.58 x 9.91

TO-CAN (NDT)

3

91.6742 mm² 10.03 x 9.14

For a newer drop-in alternative, see the LM317
Typical 0.005%/V line regulation
1% output voltage tolerance
1.5-A output current
Adjustable output down to 1.25 V
Input-output differential up to 40 V
Current limit constant with temperature
No output capacitor required
Short-circuit protected output
−40°C to 125°C operating temperature range

For a newer drop-in alternative, see the LM317
Typical 0.005%/V line regulation
1% output voltage tolerance
1.5-A output current
Adjustable output down to 1.25 V
Input-output differential up to 40 V
Current limit constant with temperature
No output capacitor required
Short-circuit protected output
−40°C to 125°C operating temperature range

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. 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 over current, 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 and can be replaced with a ceramic and appropriate ESR. 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 floating 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.

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

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. 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 over current, 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 and can be replaced with a ceramic and appropriate ESR. 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 floating 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.

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

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Technical documentation

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	Type	Title		Date
*	Data sheet	LM317A 1% Accurate 1.5A Adjustable Voltage Regulator datasheet (Rev. A)	PDF \| HTML	09 Jun 2020
	Application note	A Topical Index of TI LDO Application Notes (Rev. F)		27 Jun 2019
	EVM User's guide	LM317A-337N-EVM User's Guide		21 Jan 2016
	Technical article	Create a simple LED driver	PDF \| HTML	20 Oct 2015
	Technical article	Overview of voltage regulator packaging	PDF \| HTML	27 Aug 2015
	Technical article	Identify the most accurate linear voltage regulator	PDF \| HTML	22 Aug 2015
	Application note	AN-1028 Maximum Power Enhancement Techniques for Power Packages (Rev. B)		06 May 2013
	Application note	AN-103 LM340 Series Three Terminal Positive Regulators (Rev. A)		06 May 2013
	Application note	AN-1148 Linear Regulators: Theory of Operation and Compensation (Rev. B)		06 May 2013
	Application note	AN-182 Improving Power Supply Reliability with IC Power Regulators (Rev. B)		05 May 2013
	Application note	Method For Cal Output Voltage Tolerances in Adj Regs (Rev. A)		05 May 2013
	More literature	Die D/S LM317A MWC 3-Terminal Adj Regulator		20 Sep 2012
	Application note	Packaging Limits Range of Linear Regulators		08 May 2010
	Application note	Digital Designer's Guide to Linear Voltage Regulators & Thermal Mgmt (LDO) (Rev. A)		04 Jun 2008
	Application note	Adjustable 3-Terminal Regulator for Low-Cost Battery Charging Systems		03 Oct 2002
	Application note	Understanding the Terms and Definitions of LDO Voltage Regulators		21 Oct 1999

Design & development

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

Evaluation board

LM317A-337N-EVM — 3-pin adjustable regulator evaluation module

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 (...)

User guide: PDF