LM431AIM Equivalent & Substitute Parts

Part Overview

The LM431AIM is a shunt voltage reference IC manufactured by Texas Instruments, designed for adjustable voltage regulation applications. It provides a fixed output voltage of 2.495V with an adjustable maximum of 37V, delivering up to 100mA output current with ±2.2% tolerance. The device is packaged in 8-SOIC surface mount configuration and operates across the industrial temperature range of -40°C to 85°C.

The LM431AIM is currently in Last Time Buy status, indicating end-of-life production. Equivalent and substitute parts are necessary to ensure design continuity and long-term component availability for new production runs and system redesigns.

Key Parameters

Parameter	Value
Manufacturer	Texas Instruments
Part Number	LM431AIM
Reference Type	Shunt
Output Type	Adjustable
Voltage - Output (Min/Fixed)	2.495V
Voltage - Output (Max)	37V
Current - Output	100mA
Tolerance	±2.2%
Temperature Coefficient	50ppm/°C Typical
Current - Cathode	1mA
Operating Temperature	-40°C to 85°C
Package / Case	8-SOIC (0.154", 3.90mm Width)
Mounting Type	Surface Mount
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution of the LM431AIM is determined by strict electrical and mechanical compatibility across the following critical parameters:

Electrical Compatibility Criteria:

Reference Type: Shunt (all substitutes must be shunt-type voltage references)
Output Type: Adjustable (maintains design flexibility)
Voltage - Output (Min/Fixed): 2.495V (fixed reference point)
Current - Output: 100mA (maximum output capability)
Package / Case: 8-SOIC (0.154", 3.90mm Width) (mechanical fit requirement)
Mounting Type: Surface Mount (assembly compatibility)

Tolerance and Performance Considerations: Substitute parts may have different tolerance specifications (±0.4% to ±2.21%) and maximum output voltages (36V to 37V). These variations are acceptable provided the application requirements do not mandate the original specifications.

Temperature and Compliance: Operating temperature ranges vary between 85°C and 105°C maximum. RoHS3 compliance is required for new designs; obsolete parts may have alternative compliance status.

Parameter Comparison

Part Number	Manufacturer	Voltage Output (Min)	Voltage Output (Max)	Current Output	Tolerance	Temp Coeff	Cathode Current	Operating Temp	Status	RoHS
LM431AIM	Texas Instruments	2.495V	37V	100mA	±2.2%	50ppm/°C	1mA	-40 to 85°C	Last Time Buy	ROHS3
LM431AIM/NOPB	Texas Instruments	2.495V	37V	100mA	±2.2%	50ppm/°C	1mA	-40 to 85°C	Active	ROHS3
TL431AIDR	Texas Instruments	2.495V	36V	100mA	±1%	—	700µA	-40 to 85°C	Active	ROHS3
TL431AID	STMicroelectronics	2.495V	36V	100mA	±1%	—	700µA	-40 to 105°C	Obsolete	ROHS3
TL431BID	onsemi	2.495V	36V	100mA	±0.4%	50ppm/°C	1mA	-40 to 85°C	Obsolete	Non-compliant
TL431BIDR	Texas Instruments	2.495V	36V	100mA	±0.5%	—	700µA	-40 to 85°C	Active	ROHS3
TL431ID	STMicroelectronics	2.495V	36V	100mA	±2.21%	—	1mA	-40 to 105°C	Obsolete	ROHS3
TL431IDR	Texas Instruments	2.495V	36V	100mA	±2.2%	—	1mA	-40 to 85°C	Active	ROHS3
TL431IDRG4	Texas Instruments	2.495V	36V	100mA	±2.2%	—	1mA	-40 to 85°C	Obsolete	ROHS3
LM431CIMX	onsemi	2.495V	36V	100mA	±0.5%	50ppm/°C	1mA	-40 to 85°C	Active	ROHS3
TL431AIDG	onsemi	2.495V	36V	100mA	±1%	50ppm/°C	1mA	-40 to 85°C	Active	ROHS3

Engineering Selection Recommendations

Primary Recommendation for Direct Replacement: LM431AIM/NOPB is the direct equivalent manufactured by Texas Instruments with identical electrical specifications and Active product status. This part maintains full compatibility with existing designs and is ROHS3 compliant.

Active Status Alternatives (Recommended for New Designs):

TL431IDR (Texas Instruments): Matches tolerance (±2.2%) and cathode current (1mA) specifications. Maximum output voltage reduced to 36V. Active status ensures long-term availability.
TL431AIDR (Texas Instruments): Improved tolerance (±1%) with reduced cathode current (700µA). Active status and ROHS3 compliance. Suitable for applications requiring tighter voltage regulation.
TL431BIDR (Texas Instruments): Enhanced tolerance (±0.5%) for precision applications. Active status and ROHS3 compliance.
LM431CIMX (onsemi): Improved tolerance (±0.5%) with temperature coefficient specification (50ppm/°C). Active status and ROHS3 compliance.
TL431AIDG (onsemi): Tolerance (±1%) with temperature coefficient specification (50ppm/°C). Active status and ROHS3 compliance.

Obsolete Parts (Not Recommended for New Production): TL431AID, TL431BID, TL431ID, and TL431IDRG4 are marked Obsolete and should not be selected for new designs. These parts are available only from existing inventory and do not guarantee future supply.

Compliance Consideration: TL431BID is RoHS non-compliant and must not be used in applications requiring RoHS3 certification.

Frequently Asked Questions (FAQ)

Q: Can I use TL431IDR as a direct replacement for LM431AIM? A: Yes. TL431IDR is electrically compatible with identical tolerance (±2.2%), cathode current (1mA), and operating temperature range (-40°C to 85°C). The maximum output voltage is reduced from 37V to 36V, which is acceptable for most applications. TL431IDR is Active status and ROHS3 compliant.

Q: What is the difference between LM431AIM and TL431AIDR? A: Both are shunt voltage references in 8-SOIC packaging with 100mA output current. TL431AIDR offers improved tolerance (±1% vs ±2.2%) and lower cathode current (700µA vs 1mA). The maximum output voltage is 36V versus 37V. TL431AIDR is suitable for applications requiring tighter voltage regulation.

Q: Are all substitute parts ROHS3 compliant? A: No. TL431BID is RoHS non-compliant. All other listed substitutes are ROHS3 compliant. Verify compliance requirements for your application before selection.

Q: Can I use obsolete parts for new production? A: Obsolete parts (TL431AID, TL431BID, TL431ID, TL431IDRG4) should not be used for new production designs. These parts are available only from existing inventory with no guarantee of future supply. Select Active status parts for design continuity.

Q: What is the significance of cathode current differences? A: Cathode current affects the minimum load requirement for stable operation. LM431AIM and compatible substitutes specify either 1mA or 700µA cathode current. Lower cathode current (700µA) reduces power consumption in light-load applications. Verify your circuit design accommodates the specified cathode current.

Q: Does the 36V vs 37V maximum output voltage difference matter? A: The 1V difference is significant only for applications operating near the maximum voltage limit. For most voltage regulation circuits, 36V is sufficient. If your design requires the full 37V capability, select LM431AIM or LM431AIM/NOPB.

Q: Which substitute offers the best tolerance specification? A: TL431BID and LM431CIMX both offer ±0.4% and ±0.5% tolerance respectively, compared to ±2.2% for LM431AIM. However, TL431BID is Obsolete and RoHS non-compliant. LM431CIMX is Active and ROHS3 compliant, making it the best choice for precision applications.

Q: Are there packaging differences between substitutes? A: All listed substitutes use 8-SOIC (0.154", 3.90mm Width) surface mount packaging, ensuring mechanical compatibility. Packaging variations exist only in tape format (Cut Tape, Digi-Reel, Tube, or Tape & Reel), which affects handling and assembly but not circuit performance.

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