LM317AMDTX Linear Voltage Regulator Equivalent & Substitute Parts

Part Overview

The LM317AMDTX is a linear positive adjustable voltage regulator IC manufactured by Texas Instruments, designed for applications requiring adjustable output voltage regulation up to 1.5A. This part is classified as Last Time Buy, indicating discontinued production. The LM317AMDTX operates across a wide input voltage range (up to 40V) with adjustable output from 1.25V to 37V, making it suitable for diverse power management applications in industrial and consumer electronics.

Due to Last Time Buy status, equivalent substitute parts from active manufacturers are necessary for ongoing production and new designs. Suitable alternatives maintain identical electrical specifications and package compatibility while offering active product status and improved availability.

Key Parameters

Parameter	Value
Manufacturer Part Number	LM317AMDTX
Manufacturer	Texas Instruments
Category	Power Management (PMIC)
Package / Case	TO-252-3, DPAK (2 Leads + Tab), SC-63
Output Configuration	Positive
Output Type	Adjustable
Voltage - Input (Max)	40V
Voltage - Output (Min/Fixed)	1.25V
Voltage - Output (Max)	37V
Current - Output	1.5A
Current - Quiescent (Iq)	10 mA
PSRR	80dB ~ 65dB (120Hz)
Protection Features	Over Current, Over Temperature, Short Circuit
Operating Temperature	-40°C ~ 125°C
Mounting Type	Surface Mount
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)
REACH Status	REACH Affected

Substitute Part Grouping Explanation

Substitute parts for the LM317AMDTX are grouped based on strict electrical and mechanical compatibility criteria. The primary substitution parameters are:

Critical Matching Parameters:

Output Configuration: Positive
Output Type: Adjustable
Package / Case: TO-252-3 DPAK
Voltage - Input (Max): 40V
Voltage - Output Range: 1.2V to 37V minimum
Mounting Type: Surface Mount
RoHS Status: ROHS3 Compliant

Substitution Categories:

Category 1: Direct Parametric Equivalents (1.5A Output) Parts maintaining full 1.5A output current specification with identical electrical performance. These include LM317AMDTX/NOPB (Texas Instruments, Active status).

Category 2: Functional Equivalents (500mA Output) Parts with reduced output current (500mA) but identical voltage regulation range, package, and protection features. These include multiple onsemi and STMicroelectronics variants: LM217MDT-TR, LM317MABDTG, LM317MABDTRKG, LM317MADTRKG, LM317MBDTG, LM317MBDTRKG, LM317MDT-TR, LM317MDTG, and LM317MDTRKG.

The 500mA variants are suitable for applications where output current requirements do not exceed 500mA, providing active product status and superior availability compared to the Last Time Buy LM317AMDTX.

Parameter Comparison

Parameter	LM317AMDTX	LM317AMDTX/NOPB	LM217MDT-TR	LM317MABDTG	LM317MABDTRKG	LM317MADTRKG	LM317MBDTG	LM317MBDTRKG	LM317MDT-TR	LM317MDTG	LM317MDTRKG
Manufacturer	Texas Instruments	Texas Instruments	STMicroelectronics	onsemi	onsemi	onsemi	onsemi	onsemi	STMicroelectronics	onsemi	onsemi
Product Status	Last Time Buy	Active	Active	Active	Active	Active	Active	Active	Active	Active	Active
Output Configuration	Positive	Positive	Positive	Positive	Positive	Positive	Positive	Positive	Positive	Positive	Positive
Output Type	Adjustable	Adjustable	Adjustable	Adjustable	Adjustable	Adjustable	Adjustable	Adjustable	Adjustable	Adjustable	Adjustable
Voltage - Input (Max)	40V	40V	40V	40V	40V	40V	40V	40V	40V	40V	40V
Voltage - Output (Min/Fixed)	1.25V	1.25V	1.2V	1.2V	1.2V	1.2V	1.2V	1.2V	1.2V	1.2V	1.2V
Voltage - Output (Max)	37V	37V	37V	37V	37V	37V	37V	37V	37V	37V	37V
Current - Output	1.5A	1.5A	500mA	500mA	500mA	500mA	500mA	500mA	500mA	500mA	500mA
Current - Quiescent (Iq)	10 mA	10 mA	—	10 mA	10 mA	10 mA	10 mA	10 mA	10 mA	10 mA	10 mA
PSRR	80dB ~ 65dB (120Hz)	80dB ~ 65dB (120Hz)	80dB ~ 65dB (120Hz)	80dB ~ 65dB (120Hz)	80dB ~ 65dB (120Hz)	80dB ~ 65dB (120Hz)	80dB ~ 65dB (120Hz)	80dB ~ 65dB (120Hz)	80dB ~ 65dB (120Hz)	80dB ~ 65dB (120Hz)	80dB ~ 65dB (120Hz)
Protection Features	Over Current, Over Temperature, Short Circuit	Over Current, Over Temperature, Short Circuit	Over Temperature, Short Circuit	Over Current, Over Temperature, Short Circuit	Over Current, Over Temperature, Short Circuit	Over Current, Over Temperature, Short Circuit	Over Current, Over Temperature, Short Circuit	Over Current, Over Temperature, Short Circuit	Over Current, Over Temperature, Short Circuit	Over Current, Over Temperature, Short Circuit	Over Current, Over Temperature, Short Circuit
Operating Temperature	-40°C ~ 125°C	-40°C ~ 125°C	0°C ~ 125°C	-40°C ~ 125°C	-40°C ~ 125°C	0°C ~ 125°C	-40°C ~ 125°C	-40°C ~ 125°C	0°C ~ 125°C	0°C ~ 125°C	0°C ~ 125°C
Package / Case	TO-252-3 DPAK	TO-252-3 DPAK	TO-252-3 DPAK	TO-252-3 DPAK	TO-252-3 DPAK	TO-252-3 DPAK	TO-252-3 DPAK	TO-252-3 DPAK	TO-252-3 DPAK	TO-252-3 DPAK	TO-252-3 DPAK
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
MSL	1 (Unlimited)	2 (1 Year)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)
REACH Status	REACH Affected	REACH Unaffected	REACH Unaffected	REACH Unaffected	REACH Unaffected	REACH Unaffected	REACH Unaffected	REACH Unaffected	REACH Unaffected	REACH Unaffected	REACH Unaffected

Engineering Selection Recommendations

For Direct Replacement (1.5A Requirement): LM317AMDTX/NOPB from Texas Instruments is the primary direct substitute, maintaining identical 1.5A output current specification and full electrical compatibility. This part carries Active product status, ensuring long-term availability. The REACH Unaffected status provides regulatory advantage over the original LM317AMDTX.

For Current-Reduced Applications (≤500mA Requirement): When application load does not exceed 500mA, the following parts provide suitable alternatives with Active product status:

LM317MBDTRKG (onsemi, Cut Tape & Digi-Reel, 475,300 units in stock)
LM317MBDTG (onsemi, Tube, 485,300 units in stock)
LM317MDT-TR (STMicroelectronics, Cut Tape & Digi-Reel, 150,200 units in stock)
LM317MABDTRKG (onsemi, Cut Tape & Digi-Reel, 2,320 units in stock)
LM317MABDTG (onsemi, Tube, 2,502 units in stock)
LM317MDTRKG (onsemi, Cut Tape & Digi-Reel, 57,149 units in stock)
LM317MDTG (onsemi, Tube, 475,400 units in stock)

All 500mA variants maintain identical voltage regulation range (1.2V to 37V), PSRR performance, and TO-252-3 DPAK package compatibility. Selection among these options depends on packaging preference (Tube vs. Cut Tape & Digi-Reel) and operating temperature requirement (0°C to 125°C vs. -40°C to 125°C).

Packaging Considerations:

Cut Tape & Digi-Reel packaging suits high-volume automated assembly
Tube packaging suits lower-volume or manual assembly operations
All parts maintain identical PCB footprint and thermal characteristics

Compliance Considerations: All substitute parts maintain ROHS3 compliance. The 500mA variants carry REACH Unaffected status, providing regulatory advantage in EU markets compared to the REACH Affected original part.

Frequently Asked Questions (FAQ)

Q: Can LM317AMDTX/NOPB be used as a direct drop-in replacement for LM317AMDTX? A: Yes. LM317AMDTX/NOPB maintains identical electrical specifications (1.5A output, 1.25V to 37V adjustable range, 40V maximum input) and TO-252-3 DPAK package. The primary difference is Active product status versus Last Time Buy, and REACH Unaffected versus REACH Affected regulatory classification.

Q: What is the key difference between 1.5A and 500mA variants? A: Output current capacity. The LM317AMDTX and LM317AMDTX/NOPB deliver 1.5A maximum output current. All other listed substitutes (LM217MDT-TR, LM317MABDTG, LM317MBDTG, LM317MDTG, etc.) deliver 500mA maximum output current. Selection depends on application load requirements. For loads exceeding 500mA, only the 1.5A variants are suitable.

Q: Are all substitute parts compatible with the same PCB layout? A: Yes. All listed substitutes use the TO-252-3 DPAK package with identical pinout and thermal pad configuration. PCB layout modifications are not required for substitution.

Q: What is the difference between Cut Tape & Digi-Reel and Tube packaging? A: Both packaging formats contain identical components. Cut Tape & Digi-Reel packaging is optimized for automated pick-and-place assembly in high-volume production. Tube packaging is optimized for manual handling and lower-volume assembly. Electrical performance and reliability are identical.

Q: Do the 500mA variants have the same protection features as the original 1.5A part? A: Most do. LM317AMDTX includes Over Current, Over Temperature, and Short Circuit protection. Most 500mA variants (onsemi and STMicroelectronics LM317 series) include identical protection. LM217MDT-TR includes Over Temperature and Short Circuit protection but does not specify Over Current protection.

Q: What is the operating temperature range difference? A: LM317AMDTX and most onsemi variants operate from -40°C to 125°C. Some variants (LM217MDT-TR, LM317MADTRKG, LM317MDT-TR, LM317MDTG, LM317MDTRKG) operate from 0°C to 125°C. For applications requiring -40°C operation, select parts explicitly rated for -40°C to 125°C.

Q: What does REACH Unaffected status mean? A: REACH Unaffected indicates the component does not contain substances of very high concern (SVHC) listed under EU REACH regulations. REACH Affected (original LM317AMDTX) indicates potential SVHC content requiring compliance documentation. For EU market applications, REACH Unaffected variants are preferred.

Q: Can I use a 500mA variant in a design originally specified for 1.5A? A: Only if the actual application load does not exceed 500mA. If the design requires 1.5A capability, use LM317AMDTX/NOPB. Using an undersized component in an over-current condition will trigger protection shutdown or component failure.

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