LM431ACM Equivalent & Substitute Parts

Part Overview

The LM431ACM is a shunt voltage reference IC manufactured by onsemi, designed for adjustable voltage regulation applications. This component features a 2.5V to 36V adjustable output with ±2% tolerance and 100 mA output current capability in an 8-SOIC surface mount package. The LM431ACM is classified as obsolete, making equivalent and substitute parts necessary for new designs and ongoing production requirements. Substitute parts maintain the core electrical specifications while offering improved tolerance grades, extended temperature ranges, and active product status.

Key Parameters

Parameter	Value
Reference Type	Shunt
Output Type	Adjustable
Voltage Output (Min/Fixed)	2.5V
Voltage Output (Max)	36V
Current Output	100 mA
Tolerance	±2%
Temperature Coefficient	50 ppm/°C Typical
Current Cathode	1 mA
Operating Temperature	-25°C to 85°C
Package	8-SOIC (0.154", 3.90mm Width)
Mounting Type	Surface Mount
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution eligibility is determined by strict adherence to the following electrical and mechanical parameters:

Core Compatibility Requirements:

Reference Type: Shunt (all substitutes maintain this classification)
Output Type: Adjustable (all substitutes are adjustable references)
Package: 8-SOIC form factor (all substitutes use identical package)
Voltage Output Range: 2.5V minimum to 36V maximum (all substitutes meet or exceed this range)
Current Output: 100 mA (all substitutes provide this rating)
Temperature Coefficient: 50 ppm/°C Typical (all substitutes match this specification)
Current Cathode: 1 mA (all substitutes maintain this requirement)
Mounting Type: Surface Mount (all substitutes are surface mount)

Tolerance Grades: Substitutes are grouped by tolerance specification. The LM431ACM operates at ±2% tolerance. Substitutes with ±1% or ±0.4% tolerance are electrically compatible and represent performance improvements. Substitutes with tighter tolerances can replace the LM431ACM without functional degradation.

Temperature Range Variations: Operating temperature ranges vary among substitutes. Parts with extended temperature ranges (-40°C to 125°C) are suitable for applications requiring broader thermal operation. Parts with narrower ranges (0°C to 70°C) are suitable for standard industrial applications.

Product Status: The LM431ACM is obsolete. All listed substitutes maintain active product status, ensuring long-term availability and supply chain continuity.

Parameter Comparison

Part Number	Manufacturer	Tolerance	Voltage Output (Min)	Voltage Output (Max)	Current Output	Operating Temperature	Product Status	Packaging
LM431ACM	onsemi	±2%	2.5V	36V	100 mA	-25°C to 85°C	Obsolete	8-SOIC
LM431ACMX	National Semiconductor	±2%	2.5V	36V	100 mA	-25°C to 85°C	Active	8-SOIC
NCV431AIDR2G	onsemi	±1%	2.495V	36V	100 mA	-40°C to 125°C	Active	8-SOIC
TL431ACDG	onsemi	±1%	2.495V	36V	100 mA	0°C to 70°C	Active	8-SOIC
TL431ACDR2G	onsemi	±1%	2.495V	36V	100 mA	0°C to 70°C	Active	8-SOIC
TL431AIDG	onsemi	±1%	2.495V	36V	100 mA	-40°C to 85°C	Active	8-SOIC
TL431AIDR2G	onsemi	±1%	2.495V	36V	100 mA	-40°C to 85°C	Active	8-SOIC
TL431BCDR2G	onsemi	±0.4%	2.495V	36V	100 mA	0°C to 70°C	Active	8-SOIC
TL431BIDG	onsemi	±0.4%	2.495V	36V	100 mA	-40°C to 85°C	Active	8-SOIC
TL431BIDR2G	onsemi	±0.4%	2.495V	36V	100 mA	-40°C to 85°C	Active	8-SOIC
TL431BVDR2G	onsemi	±0.4%	2.495V	36V	100 mA	-40°C to 125°C	Active	8-SOIC

Engineering Selection Recommendations

Direct Replacement (Identical Specifications): LM431ACMX is the direct equivalent manufactured by National Semiconductor. It maintains identical electrical specifications (±2% tolerance, -25°C to 85°C operating range) and active product status, making it the primary replacement for the obsolete LM431ACM.

Performance-Enhanced Substitutes (±1% Tolerance): NCV431AIDR2G, TL431ACDG, TL431ACDR2G, TL431AIDG, and TL431AIDR2G offer improved tolerance (±1%) while maintaining all core electrical parameters. These parts are suitable for applications requiring tighter output voltage accuracy. NCV431AIDR2G and TL431AIDG/TL431AIDR2G provide extended temperature ranges (-40°C to 125°C and -40°C to 85°C respectively), supporting broader thermal operating conditions.

High-Precision Substitutes (±0.4% Tolerance): TL431BCDR2G, TL431BIDG, TL431BIDR2G, and TL431BVDR2G deliver the highest precision at ±0.4% tolerance. TL431BVDR2G extends the operating temperature range to -40°C to 125°C, providing both precision and thermal flexibility for demanding applications.

Compliance and Certifications: All substitute parts maintain REACH Unaffected status and EAR99 classification. NCV431AIDR2G carries AEC-Q100 automotive qualification and is suitable for automotive applications. All active substitutes comply with ROHS3 standards where applicable.

Packaging Considerations: Substitutes are available in multiple packaging formats: Tube, Cut Tape (CT), Tape & Reel (TR), and Cut Tape with Digi-Reel. Selection depends on production volume and assembly requirements. All maintain the 8-SOIC form factor for direct PCB compatibility.

Frequently Asked Questions (FAQ)

Q: Can I use a TL431 series part to replace the LM431ACM? A: Yes. TL431 series parts (TL431ACDG, TL431ACDR2G, TL431AIDG, TL431AIDR2G, TL431BCDR2G, TL431BIDG, TL431BIDR2G, TL431BVDR2G) are electrically compatible substitutes. All maintain the 8-SOIC package, 100 mA output current, 36V maximum voltage, and 50 ppm/°C temperature coefficient. Tolerance grades vary from ±1% to ±0.4%, representing performance improvements over the original ±2% specification.

Q: What is the difference between ±2%, ±1%, and ±0.4% tolerance grades? A: Tolerance specifies the accuracy of the output voltage at nominal conditions. The LM431ACM operates at ±2% tolerance, meaning the output voltage can vary by up to 2% from the nominal 2.5V reference. Substitutes with ±1% tolerance provide tighter accuracy (±1% variation), and ±0.4% tolerance parts deliver the highest precision (±0.4% variation). Tighter tolerance grades are suitable for applications requiring more stable reference voltages.

Q: Which substitute should I select for automotive applications? A: NCV431AIDR2G is qualified to AEC-Q100 automotive standards and operates across -40°C to 125°C, making it suitable for automotive environments. This part combines ±1% tolerance with extended temperature range and automotive-grade reliability.

Q: Are all substitutes available in the same 8-SOIC package? A: Yes. All listed substitutes use the 8-SOIC (0.154", 3.90mm Width) package, ensuring direct PCB compatibility with the LM431ACM. Packaging format (Tube, Cut Tape, Tape & Reel) varies by part number and affects handling and assembly processes, not electrical performance.

Q: What is the difference between operating temperature ranges? A: Operating temperature range defines the thermal environment in which the part functions within specification. The LM431ACM operates from -25°C to 85°C. Substitutes offer three temperature ranges: 0°C to 70°C (standard industrial), -40°C to 85°C (extended), and -40°C to 125°C (automotive/high-temperature). Select based on your application's thermal requirements.

Q: Can I substitute a ±0.4% tolerance part for a ±2% tolerance requirement? A: Yes. A ±0.4% tolerance part exceeds the ±2% tolerance requirement and provides superior performance. Tighter tolerance substitutes are always compatible with applications designed for looser tolerances, as they deliver better accuracy.

Q: What does "Moisture Sensitivity Level (MSL)" mean? A: MSL indicates the component's sensitivity to moisture absorption during storage and handling. MSL 1 (Unlimited) means the part has unlimited shelf life and requires no special moisture control during storage, making it suitable for standard inventory management.

Q: Are all substitutes RoHS compliant? A: All active substitute parts listed comply with ROHS3 standards. The LM431ACM does not specify RoHS status. ROHS3 compliance ensures the parts contain no restricted hazardous substances, meeting environmental regulations for electronic components.

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