LM431AIM3X Equivalent & Substitute Parts

Part Overview

The LM431AIM3X is a shunt voltage reference IC manufactured by Texas Instruments, designed for adjustable voltage regulation applications. This component features a 2.495V adjustable output with ±2.2% tolerance and supports output currents up to 100 mA in a compact SOT-23-3 surface mount package. The part is currently listed as obsolete, making identification of equivalent and substitute components essential for ongoing design support and production continuity.

Key Parameters

Parameter	Value
Reference Type	Shunt
Output Type	Adjustable
Voltage - Output (Min/Fixed)	2.495V
Voltage - Output (Max)	37 V
Current - Output	100 mA
Tolerance	±2.2%
Temperature Coefficient	50ppm/°C Typical
Current - Cathode	1 mA
Operating Temperature	-40°C ~ 85°C (TA)
Package / Case	TO-236-3, SC-59, SOT-23-3
Mounting Type	Surface Mount
RoHS Status	RoHS non-compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution for the LM431AIM3X is determined by strict alignment of electrical and mechanical parameters. The critical substitution criteria are:

Electrical Parameters:

Reference type (Shunt)
Output type (Adjustable)
Minimum output voltage (2.495V)
Maximum output voltage (36V or higher)
Output current capability (100 mA)
Package compatibility (SOT-23-3)

Compliance Parameters:

RoHS status and regulatory certifications
Product lifecycle status (Active vs. Obsolete)

Substitute parts are grouped into three categories based on their relationship to the main part:

Direct Manufacturer Equivalents: Parts from Texas Instruments with identical electrical specifications and the same base product number (LM431), differing only in packaging designation or RoHS compliance status.

Parametric Equivalents: Parts with identical electrical performance specifications and package type, representing alternative product codes within the same manufacturer's portfolio.

Manufacturer Recommended Alternatives: Parts from alternative manufacturers (Diodes Incorporated) that meet or exceed the electrical specifications while offering improved performance characteristics such as tighter tolerance or lower temperature coefficient.

Parameter Comparison

Parameter	LM431AIM3X	LM431AIM3X/NOPB	LM431AIM3	LM431AIM3/NOPB	AS431HMBNTR-G1
Manufacturer	Texas Instruments	Texas Instruments	Texas Instruments	Texas Instruments	Diodes Incorporated
Reference Type	Shunt	Shunt	Shunt	Shunt	Shunt
Output Type	Adjustable	Adjustable	Adjustable	Adjustable	Adjustable
Voltage - Output (Min/Fixed)	2.495V	2.495V	2.495V	2.495V	2.495V
Voltage - Output (Max)	37 V	37 V	37 V	37 V	36 V
Current - Output	100 mA	100 mA	100 mA	100 mA	100 mA
Tolerance	±2.2%	±2.2%	±2.2%	±2.2%	±1%
Temperature Coefficient	50ppm/°C Typical	50ppm/°C Typical	50ppm/°C Typical	50ppm/°C Typical	20ppm/°C Typical
Current - Cathode	1 mA	1 mA	1 mA	1 mA	500 µA
Operating Temperature	-40°C ~ 85°C (TA)	-40°C ~ 85°C (TA)	-40°C ~ 85°C (TA)	-40°C ~ 85°C (TA)	-40°C ~ 125°C (TA)
Package / Case	TO-236-3, SC-59, SOT-23-3	TO-236-3, SC-59, SOT-23-3	TO-236-3, SC-59, SOT-23-3	TO-236-3, SC-59, SOT-23-3	TO-236-3, SC-59, SOT-23-3
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Product Status	Obsolete	Active	Last Time Buy	Active	Active
RoHS Status	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

For Direct Replacement (Identical Specifications): LM431AIM3X/NOPB is the primary direct substitute, offering identical electrical specifications with active product status and ROHS3 compliance. This part is recommended for designs requiring exact parameter matching with modern regulatory compliance.

For Continued Production Support: LM431AIM3/NOPB provides parametric equivalence with active product status and full ROHS3 compliance. This part ensures long-term availability and supply chain continuity for production applications.

For Enhanced Performance Requirements: AS431HMBNTR-G1 from Diodes Incorporated offers superior electrical characteristics including tighter tolerance (±1% vs. ±2.2%), lower temperature coefficient (20ppm/°C vs. 50ppm/°C), and extended operating temperature range (-40°C to 125°C vs. -40°C to 85°C). This part is suitable for applications requiring improved accuracy and thermal stability. The maximum output voltage specification of 36V remains compatible with the original 37V specification for most practical applications.

All substitute parts maintain identical package geometry (SOT-23-3) and mounting type (Surface Mount), ensuring direct PCB compatibility without layout modifications.

Frequently Asked Questions (FAQ)

Q: Can LM431AIM3X/NOPB be used as a direct replacement for LM431AIM3X? A: Yes. LM431AIM3X/NOPB is electrically and mechanically identical to LM431AIM3X. The primary difference is product status (Active vs. Obsolete) and RoHS compliance (ROHS3 Compliant vs. non-compliant). This is the recommended direct substitute.

Q: What is the difference between LM431AIM3 and LM431AIM3/NOPB? A: Both parts are parametric equivalents with identical electrical specifications. The "/NOPB" designation indicates lead-free, RoHS-compliant packaging. LM431AIM3/NOPB is preferred for new designs due to active product status and regulatory compliance.

Q: Is AS431HMBNTR-G1 compatible with LM431AIM3X in all applications? A: AS431HMBNTR-G1 is electrically compatible with superior performance characteristics. The ±1% tolerance and 20ppm/°C temperature coefficient represent improvements over the original ±2.2% and 50ppm/°C specifications. The 36V maximum output voltage is compatible with the 37V specification for standard applications. Extended temperature range (-40°C to 125°C) provides additional operational margin.

Q: Are all substitute parts in the same package? A: Yes. All substitute parts use the SOT-23-3 package (TO-236-3, SC-59). No PCB layout modifications are required for substitution.

Q: Which substitute part should be selected for new designs? A: LM431AIM3/NOPB is recommended for new designs, offering active product status, ROHS3 compliance, and guaranteed long-term availability. AS431HMBNTR-G1 is recommended if enhanced accuracy and thermal stability are required.

Q: What is the significance of the "Last Time Buy" status for LM431AIM3? A: Last Time Buy status indicates that Texas Instruments will discontinue this part after a specified date. Existing inventory may be available, but new production orders should transition to LM431AIM3/NOPB or alternative manufacturers' equivalents for supply continuity.

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