LM317LMX Linear Voltage Regulator Equivalent & Substitute Parts

Part Overview

The LM317LMX is a linear positive adjustable voltage regulator IC manufactured by onsemi, designed for applications requiring adjustable output voltage regulation up to 100mA. The device features 8-SOIC surface mount packaging and operates across a 0°C to 125°C temperature range with input voltage capability up to 40V.

The LM317LMX is classified as obsolete product status. Identifying equivalent and substitute parts is necessary to maintain design continuity, ensure supply chain availability, and support ongoing production requirements for systems utilizing this regulator topology.

Substiute Parts

LM317LMX

onsemiIn Stock: 6224LM317LMX Datasheet

Current PartRFQ

LM317LDR2G

onsemiIn Stock: 980453LM317LDR2G Datasheet

DirectRFQ

LM217LD13TR

STMicroelectronicsIn Stock: 40567LM217LD13TR Datasheet

SimilarRFQ

LM317LD13TR

STMicroelectronicsIn Stock: 886604LM317LD13TR Datasheet

Parametric EquivalentRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the LM317LMX is determined by the following critical parameters:

Mandatory Matching Parameters:

• Output Configuration: Positive
• Output Type: Adjustable
• Number of Regulators: 1
• Voltage - Input (Max): 40V
• Voltage - Output (Min/Fixed): 1.2V
• Voltage - Output (Max): 37V
• Current - Output: 100mA
• Package / Case: 8-SOIC (0.154", 3.90mm Width)
• Mounting Type: Surface Mount

Allowable Variation Parameters:

• Current - Quiescent (Iq): 5 mA to 10 mA
• PSRR: 65dB to 80dB (120Hz)
• Operating Temperature: 0°C ~ 125°C or -40°C ~ 125°C
• Protection Features: Over Current, Over Temperature, Short Circuit (all three required)

The substitute parts listed below meet these criteria and are classified as direct manufacturer equivalents, similar manufacturer alternatives, or parametric equivalents based on their alignment with the specified parameters.

Parameter Comparison

Engineering Selection Recommendations

LM317LDR2G (onsemi) is the primary direct manufacturer equivalent. This part maintains active product status, identical electrical specifications, and matching operating temperature range. RoHS3 compliance and unlimited moisture sensitivity rating align with modern manufacturing standards. This substitute provides the highest compatibility with the original LM317LMX design.

LM317LD13TR (STMicroelectronics) is a parametric equivalent offering identical core functionality with lower quiescent current (5 mA versus 10 mA), which may provide improved efficiency in battery-powered applications. Active product status and RoHS3 compliance support long-term availability. Operating temperature range matches the original specification.

LM217LD13TR (STMicroelectronics) is a similar manufacturer alternative based on the LM217 base product number. This part meets all critical electrical parameters but lacks over-current protection compared to the original LM317LMX. Extended operating temperature range (-40°C ~ 125°C) provides additional thermal margin for demanding environments. Selection of this part requires confirmation that over-current protection is not required by the application circuit design.

All substitute parts maintain identical 8-SOIC package geometry, surface mount configuration, and core voltage regulation topology, ensuring direct PCB compatibility without layout modifications.

Frequently Asked Questions (FAQ)

Q: Can LM317LDR2G directly replace LM317LMX without circuit modifications?

A: Yes. LM317LDR2G maintains identical electrical specifications, package geometry, and operating temperature range. No circuit modifications are required for direct substitution.

Q: What is the difference between LM317LD13TR and LM317LDR2G?

A: Both are LM317 base product equivalents with identical core specifications. LM317LD13TR features lower quiescent current (5 mA versus 10 mA) and is manufactured by STMicroelectronics, while LM317LDR2G is manufactured by onsemi. The lower quiescent current in LM317LD13TR may reduce standby power consumption in applications with extended idle periods.

Q: Why does LM217LD13TR lack over-current protection?

A: LM217LD13TR is based on the LM217 product line, which implements a different protection architecture. This part includes over-temperature and short-circuit protection but does not include dedicated over-current protection. Applications requiring over-current protection must use LM317LDR2G or LM317LD13TR.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. LM317LDR2G, LM217LD13TR, and LM317LD13TR are all RoHS3 compliant, meeting current environmental and regulatory requirements.

Q: Can I use LM217LD13TR in a design originally specified for LM317LMX?

A: LM217LD13TR meets all critical voltage, current, and package specifications. However, the absence of over-current protection requires circuit-level evaluation. If the application circuit relies on the regulator's over-current protection feature, LM317LD13TR or LM317LDR2G must be used instead.

Q: What is the impact of the extended operating temperature range in LM217LD13TR?

A: LM217LD13TR operates from -40°C to 125°C compared to 0°C to 125°C for the original LM317LMX. This extended lower temperature limit provides additional thermal margin for applications in cold environments but does not affect performance within the original 0°C to 125°C specification window.

Q: Are there inventory considerations when selecting a substitute?

A: LM317LDR2G offers the highest inventory availability (980,400 units), followed by LM317LD13TR (886,524 units) and LM217LD13TR (40,496 units). Inventory levels should be evaluated against project timeline and volume requirements.