FAN431ZXA Equivalent & Substitute Parts

Part Overview

The FAN431ZXA is a shunt voltage reference IC manufactured by onsemi, designed for adjustable voltage regulation applications. This component features a 2.495V adjustable output with ±2% tolerance and supports up to 100 mA output current in a TO-92-3 package. The part is currently obsolete, making equivalent substitutes necessary for new designs and ongoing production support.

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	±2%
Temperature Coefficient	50ppm/°C Typical
Current - Cathode	1 mA
Operating Temperature	-25°C ~ 85°C (TA)
Mounting Type	Through Hole
Package / Case	TO-226-3, TO-92-3 (TO-226AA) Formed Leads

Substitute Part Grouping Explanation

Substitution for the FAN431ZXA is determined by the following critical parameters:

Reference Type & Output Type: All substitutes must be shunt-type adjustable voltage references
Voltage Range: Output voltage must span 2.495V to 36V minimum
Current Rating: Output current capability must be at least 100 mA
Package Compatibility: TO-92-3 package with through-hole mounting
Tolerance & Temperature Coefficient: Tolerance of ±2% or better; temperature coefficient of 50ppm/°C or lower
Operating Temperature: Minimum range of -25°C to 85°C

Substitutes are grouped into three categories: direct equivalents (matching all parameters), improved tolerance variants (tighter tolerance specifications), and upgraded versions (extended temperature range or enhanced performance).

Parameter Comparison

Part Number	Manufacturer	Tolerance	Output Voltage (Min/Max)	Output Current	Temp Coefficient	Operating Temp	Product Status	Package
FAN431ZXA	onsemi	±2%	2.495V / 36V	100 mA	50ppm/°C	-25°C ~ 85°C	Obsolete	TO-92-3
FAN431AZXA	Fairchild Semiconductor	±1%	2.495V / 36V	100 mA	50ppm/°C	-25°C ~ 85°C	Active	TO-92-3
TL431AILPRAG	onsemi	±1%	2.495V / 36V	100 mA	50ppm/°C	-40°C ~ 85°C	Active	TO-92-3
TL431AILPRPG	onsemi	±1%	2.495V / 36V	100 mA	50ppm/°C	-40°C ~ 85°C	Obsolete	TO-92-3
TL431BILPRAG	onsemi	±0.4%	2.495V / 36V	100 mA	50ppm/°C	-40°C ~ 85°C	Active	TO-92-3
TL431ILPRAG	onsemi	±2.2%	2.495V / 36V	100 mA	50ppm/°C	-40°C ~ 85°C	Active	TO-92-3
TL431ILPRPG	onsemi	±2.2%	2.495V / 36V	100 mA	50ppm/°C	-40°C ~ 85°C	Active	TO-92-3
TL431IZT	STMicroelectronics	±2.21%	2.495V / 36V	100 mA	Not specified	-40°C ~ 105°C	Active	TO-92-3
AS431AZTR-E1	Diodes Incorporated	±0.5%	2.5V / 36V	100 mA	20ppm/°C	-40°C ~ 125°C	Active	TO-92-3
AS431IAZTR-G1	Diodes Incorporated	±0.5%	2.5V / 36V	100 mA	Not specified	-40°C ~ 125°C	Active	TO-92-3
TL1431AIZT	STMicroelectronics	±0.25%	2.5V / 36V	100 mA	100ppm/°C	-40°C ~ 105°C	Active	TO-92-3

Engineering Selection Recommendations

Direct Equivalents (Active Status)

FAN431AZXA from Fairchild Semiconductor provides the closest match with identical electrical specifications and operating temperature range. This part is currently active and offers improved tolerance (±1% versus ±2%), making it suitable for direct replacement in existing designs.

Primary Substitutes (onsemi TL431 Series)

The TL431AILPRAG and TL431ILPRAG from onsemi are functionally equivalent with extended lower temperature rating (-40°C versus -25°C). TL431AILPRAG offers tighter tolerance (±1%), while TL431ILPRAG maintains tolerance comparable to the original (±2.2%). Both are active products with established supply chains.

Enhanced Performance Options

TL431BILPRAG provides superior tolerance specification (±0.4%) while maintaining all other electrical parameters. This variant is recommended for applications requiring tighter voltage regulation accuracy.

Extended Temperature Range Alternatives

TL431IZT from STMicroelectronics extends the upper operating temperature to 105°C, suitable for high-temperature environments. AS431AZTR-E1 and AS431IAZTR-G1 from Diodes Incorporated offer the widest temperature range (-40°C to 125°C) with improved tolerance (±0.5%) and lower temperature coefficient (20ppm/°C for AS431AZTR-E1).

Premium Precision Option

TL1431AIZT from STMicroelectronics delivers the tightest tolerance specification (±0.25%) with extended temperature range (-40°C to 105°C), suitable for precision voltage reference applications requiring superior accuracy.

All recommended substitutes maintain RoHS3 compliance and REACH unaffected status consistent with the original part.

Frequently Asked Questions (FAQ)

Q: Can I use a substitute part with tighter tolerance than the FAN431ZXA?

A: Yes. Parts with tolerance specifications tighter than ±2% (such as ±1%, ±0.5%, or ±0.25%) are fully compatible and provide improved voltage regulation accuracy. The application circuit will function correctly with these enhanced specifications.

Q: What is the impact of extended operating temperature range on substitution?

A: Extended temperature ranges (such as -40°C to 105°C or -40°C to 125°C) are backward compatible with the original -25°C to 85°C specification. These parts are suitable for applications requiring operation beyond the original temperature limits without circuit modification.

Q: Are all substitute parts available in TO-92-3 package?

A: All listed substitutes are available in TO-92-3 package configuration with through-hole mounting, ensuring direct mechanical compatibility with existing PCB layouts.

Q: What is the significance of cathode current specifications?

A: Cathode current (ranging from 50 µA to 1 mA across variants) represents the minimum operating current required for proper voltage reference operation. Lower cathode current requirements provide design flexibility for high-impedance applications.

Q: Can I substitute a part with different output voltage specification?

A: Output voltage specifications must remain within the 2.495V to 2.5V range for the adjustable output minimum. Parts specifying 2.5V minimum (such as AS431 and TL1431 series) are compatible with designs using 2.495V reference, as the adjustable output accommodates this variation through external resistor networks.

Q: Which substitute offers the best long-term availability?

A: AS431AZTR-E1 and AS431IAZTR-G1 from Diodes Incorporated show the highest inventory levels (117,200 and 56,350 units respectively) and active product status, indicating strong long-term supply continuity.

Q: Are there compliance differences between substitute options?

A: All substitutes maintain RoHS3 compliance and REACH unaffected status. Moisture sensitivity levels are consistent (MSL 1 - Unlimited) across all variants, ensuring equivalent handling and storage requirements.

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