LM431CIZ Equivalent & Substitute Parts

Part Overview

The LM431CIZ is a shunt voltage reference IC manufactured by onsemi, designed for adjustable voltage regulation applications. This component features a 2.495V adjustable output with ±0.5% tolerance and supports output currents up to 100 mA across a 36V maximum range. The part is classified as obsolete, making equivalent substitutes necessary for new designs and ongoing production requirements. Substitute parts must maintain functional compatibility while meeting current product availability and compliance standards.

Key Parameters

Parameter	Value
Reference Type	Shunt
Output Type	Adjustable
Voltage - Output (Min/Fixed)	2.495V
Voltage - Output (Max)	36V
Current - Output	100 mA
Tolerance	±0.5%
Temperature Coefficient	50ppm/°C Typical
Current - Cathode	1 mA
Operating Temperature	-40°C ~ 85°C
Mounting Type	Through Hole
Package / Case	TO-226-3, TO-92-3

Substitute Part Grouping Explanation

Substitution eligibility is determined by the following critical parameters:

Reference Type: Must be Shunt
Output Type: Must be Adjustable
Voltage Range: Output minimum must support 2.495V; maximum must be ≥36V
Current Rating: Output current must be ≥100 mA
Tolerance: ±0.5% or better (lower tolerance values are acceptable)
Mounting Type: Must be Through Hole
Package: Must be TO-92-3 or TO-226-3 compatible

Substitute parts are grouped into two categories: direct equivalents with matching or superior tolerance specifications, and functional alternatives with relaxed tolerance that maintain electrical compatibility.

Parameter Comparison

Part Number	Manufacturer	Voltage Min	Voltage Max	Current Output	Tolerance	Temp Coeff	Operating Temp	Product Status
LM431CIZ	onsemi	2.495V	36V	100 mA	±0.5%	50ppm/°C	-40°C ~ 85°C	Obsolete
TL431BILPG	onsemi	2.495V	36V	100 mA	±0.4%	50ppm/°C	-40°C ~ 85°C	Active
TL431AILPG	onsemi	2.495V	36V	100 mA	±1%	50ppm/°C	-40°C ~ 85°C	Active
TL431ILPG	onsemi	2.495V	36V	100 mA	±2.2%	50ppm/°C	-40°C ~ 85°C	Active
AS431AZTR-E1	Diodes Incorporated	2.5V	36V	100 mA	±0.5%	20ppm/°C	-40°C ~ 125°C	Active
AS431IAZTR-G1	Diodes Incorporated	2.5V	36V	100 mA	±0.5%	-	-40°C ~ 125°C	Active
LM431AIZ/NOPB	Texas Instruments	2.495V	37V	100 mA	±2.2%	50ppm/°C	-40°C ~ 85°C	Active
LM431CIZ/NOPB	Texas Instruments	2.5V	37V	100 mA	-0.6%, +0.4%	50ppm/°C	-40°C ~ 85°C	Active
TL1431CLP	Texas Instruments	2.5V	36V	100 mA	±0.4%	-	0°C ~ 70°C	Active
TL1431CLPE3	Texas Instruments	2.5V	36V	100 mA	±0.4%	-	0°C ~ 70°C	Obsolete
TL1431IZ	STMicroelectronics	2.5V	36V	100 mA	±0.4%	100ppm/°C	-40°C ~ 105°C	Active

Engineering Selection Recommendations

Primary Substitutes (Matching or Superior Tolerance)

TL431BILPG (onsemi) and AS431AZTR-E1 (Diodes Incorporated) are the preferred substitutes. Both maintain ±0.4% to ±0.5% tolerance specifications and are currently in active production status. TL431BILPG provides identical electrical characteristics with onsemi manufacturing continuity. AS431AZTR-E1 offers extended operating temperature range (-40°C to 125°C) and improved temperature coefficient (20ppm/°C), beneficial for applications requiring enhanced thermal stability.

Secondary Substitutes (Relaxed Tolerance)

TL431AILPG (±1% tolerance) and LM431AIZ/NOPB (±2.2% tolerance) are functionally compatible alternatives when tolerance relaxation is acceptable. Both maintain active product status and identical voltage/current specifications. These options are suitable for applications where precision requirements are less stringent than the original ±0.5% specification.

Compliance Considerations

All recommended substitutes carry RoHS3 compliance and REACH Unaffected status, matching the original part's regulatory standing. Texas Instruments variants (LM431CIZ/NOPB, TL1431CLP) provide direct cross-reference compatibility with established supply chains. Diodes Incorporated parts (AS431AZTR-E1, AS431IAZTR-G1) offer superior availability with 56,350 to 117,200 units in stock.

Temperature Range Considerations

Applications operating below 0°C or above 85°C should prioritize AS431AZTR-E1 (-40°C to 125°C) or TL1431IZ (-40°C to 105°C). Standard temperature range parts (TL1431CLP, TL1431CLPE3) are limited to 0°C to 70°C operation and are unsuitable for extended temperature applications.

Frequently Asked Questions (FAQ)

Q: Can TL431AILPG replace LM431CIZ in all applications?

A: TL431AILPG is electrically compatible for most applications. The tolerance difference (±1% vs ±0.5%) is the primary consideration. Applications requiring precision voltage reference accuracy better than ±1% must use TL431BILPG or AS431AZTR-E1 instead.

Q: What is the difference between TO-92-3 and TO-226-3 packaging?

A: TO-92-3 and TO-226-3 are equivalent designations for the same three-lead through-hole package. Both terms refer to the standard plastic DIP package with identical pin spacing and mechanical dimensions. All listed substitutes are compatible with existing TO-92-3 footprints.

Q: Is AS431AZTR-E1 a direct replacement for LM431CIZ?

A: AS431AZTR-E1 is functionally equivalent with superior specifications. It maintains ±0.5% tolerance, supports 100 mA output current, and operates across 2.5V to 36V range. The extended temperature range (-40°C to 125°C) and lower temperature coefficient (20ppm/°C) make it suitable for demanding thermal environments. Pin configuration and package are compatible.

Q: Why is LM431CIZ marked as obsolete?

A: Obsolete status indicates the part is no longer manufactured by onsemi. Active substitutes from onsemi (TL431 series) and other manufacturers provide equivalent or superior functionality with ongoing production support and supply availability.

Q: Can I use TL1431CLP in applications requiring -40°C operation?

A: No. TL1431CLP operating temperature range is 0°C to 70°C, making it unsuitable for -40°C minimum temperature requirements. Use AS431AZTR-E1, TL1431IZ, or other parts rated to -40°C minimum.

Q: What is the significance of cathode current (1 mA vs 50 µA)?

A: Cathode current represents the minimum operating current required for proper voltage reference operation. Parts with 1 mA cathode current requirement consume more quiescent current than 50 µA variants. For low-power applications, AS431IAZTR-G1 with 50 µA cathode current may offer power efficiency advantages.

Q: Are all substitutes RoHS3 compliant?

A: All listed active substitutes carry RoHS3 compliance certification. Obsolete parts (LM431CIZ, TL1431CLPE3) maintain RoHS3 status but are no longer in production. Verify compliance documentation for specific procurement requirements.

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