TL431AILP Equivalent & Substitute Parts

Part Overview

The TL431AILP is a shunt voltage reference IC manufactured by Microchip Technology, classified as a Power Management (PMIC) component. This adjustable reference device operates across a 2.5V to 36V output range with ±1% tolerance and supports 100 mA output current in a TO-92-3 through-hole package. The TL431AILP is currently listed as obsolete, making equivalent and substitute parts necessary for ongoing design support and production continuity. Substitute components must maintain electrical compatibility across voltage output, current capacity, tolerance specifications, and thermal operating ranges while accommodating the through-hole TO-92-3 package format.

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	±1%
Temperature Coefficient	30ppm/°C Typical
Current - Cathode	1 mA
Operating Temperature	-40°C ~ 85°C
Mounting Type	Through Hole
Package / Case	TO-226-3, TO-92-3 Long Body
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution of the TL431AILP 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 references)
Output Type: Adjustable (maintains voltage adjustment capability)
Voltage Range: 2.5V minimum to 36V maximum output (full range coverage required)
Current - Output: 100 mA (minimum required capacity)
Tolerance: ±1% or better (equal or tighter tolerance acceptable)
Current - Cathode: 1 mA or lower (lower values acceptable for reduced quiescent current)

Mechanical Compatibility Criteria:

Mounting Type: Through Hole (package form factor)
Package / Case: TO-226-3 or TO-92-3 (identical pinout and footprint)

Environmental & Compliance Criteria:

Operating Temperature: Must support -40°C minimum (TL431AILP baseline)
RoHS Status: ROHS3 Compliant (regulatory requirement)
Moisture Sensitivity Level: MSL 1 (Unlimited)

Substitute parts are grouped into two categories: Direct Upgrade (active product status with enhanced specifications) and Equivalent Alternatives (active products meeting or exceeding all electrical and mechanical requirements).

Parameter Comparison

Part Number	Manufacturer	Product Status	Voltage Output (Min)	Voltage Output (Max)	Current Output	Tolerance	Temp Coefficient	Cathode Current	Operating Temp Range	Package
TL431AILP	Microchip Technology	Obsolete	2.5V	36V	100 mA	±1%	30ppm/°C	1 mA	-40°C ~ 85°C	TO-92-3
TL431AIZ	STMicroelectronics	Active	2.495V	36V	100 mA	±1%	—	700 µA	-40°C ~ 105°C	TO-92-3
AS431AZTR-E1	Diodes Incorporated	Active	2.5V	36V	100 mA	±0.5%	20ppm/°C	1 mA	-40°C ~ 125°C	TO-92-3
AS431AZTR-G1	Diodes Incorporated	Active	2.5V	36V	100 mA	±0.5%	20ppm/°C	1 mA	-40°C ~ 125°C	TO-92-3
AS431BZTR-E1	Diodes Incorporated	Active	2.5V	36V	100 mA	±1%	20ppm/°C	1 mA	-40°C ~ 125°C	TO-92-3
AS431BZTR-G1	Diodes Incorporated	Active	2.5V	36V	100 mA	±1%	20ppm/°C	1 mA	-40°C ~ 125°C	TO-92-3
AS431IAZTR-G1	Diodes Incorporated	Active	2.5V	36V	100 mA	±0.5%	—	50 µA	-40°C ~ 125°C	TO-92-3
AZ431AZ-ATRG1	Diodes Incorporated	Active	2.5V	36V	100 mA	±0.4%	20ppm/°C	1 mA	-40°C ~ 125°C	TO-92-3
KA431AZBU	Fairchild Semiconductor	Active	2.495V	36V	100 mA	±1%	50ppm/°C	1 mA	-25°C ~ 85°C	TO-92-3
LT1431CZ#PBF	Analog Devices Inc.	Active	2.5V	36V	100 mA	±0.4%	30ppm/°C	1 mA	0°C ~ 70°C	TO-92-3
LT1431IZ#PBF	Analog Devices Inc.	Active	2.5V	36V	100 mA	±0.4%	50ppm/°C	1 mA	-40°C ~ 85°C	TO-92-3

Engineering Selection Recommendations

Direct Upgrade Option:

The TL431AIZ (STMicroelectronics) serves as the primary direct upgrade. This part maintains the ±1% tolerance specification of the original TL431AILP while offering active product status, extended operating temperature range (-40°C to 105°C versus -40°C to 85°C), and reduced cathode current (700 µA versus 1 mA). The output voltage minimum of 2.495V is functionally equivalent to the 2.5V specification within the ±1% tolerance band. ROHS3 compliance and MSL 1 rating ensure regulatory and environmental compatibility.

Equivalent Alternatives with Enhanced Specifications:

Parts from Diodes Incorporated (AS431AZTR-E1, AS431AZTR-G1, AS431BZTR-E1, AS431BZTR-G1, AS431IAZTR-G1, AZ431AZ-ATRG1) provide active product status with extended temperature ranges (-40°C to 125°C). The AS431 and AZ431 series offer tolerance improvements (±0.5% to ±0.4%) and lower cathode currents (50 µA to 1 mA), enabling reduced quiescent power consumption. All maintain 100 mA output current and 36V maximum voltage specifications.

Conditional Alternatives:

The LT1431IZ#PBF (Analog Devices Inc.) matches the original operating temperature range (-40°C to 85°C) with ±0.4% tolerance and 30ppm/°C temperature coefficient identical to the TL431AILP. However, the LT1431CZ#PBF variant operates only to 70°C maximum, restricting its use to applications not requiring the full -40°C to 85°C range.

The KA431AZBU (Fairchild Semiconductor) maintains ±1% tolerance and -25°C to 85°C operating range but does not extend to the -40°C minimum of the original specification, limiting its applicability to designs with relaxed low-temperature requirements.

All recommended substitutes maintain TO-92-3 package compatibility, ROHS3 compliance, and shunt reference architecture required for direct functional replacement.

Frequently Asked Questions (FAQ)

Q: Can I use AS431AZTR-E1 or AS431AZTR-G1 as direct replacements for TL431AILP?

A: Yes. Both parts meet all electrical and mechanical compatibility requirements. They provide ±0.5% tolerance (tighter than the original ±1%), identical 100 mA output current, 2.5V to 36V voltage range, and TO-92-3 package compatibility. Operating temperature extends to 125°C, exceeding the original -40°C to 85°C range. These parts are functionally superior and actively manufactured.

Q: What is the difference between AS431BZTR-E1 and AS431AZTR-E1?

A: The primary difference is tolerance specification. AS431AZTR-E1 provides ±0.5% tolerance, while AS431BZTR-E1 provides ±1% tolerance matching the original TL431AILP. Both share identical voltage range (2.5V to 36V), output current (100 mA), cathode current (1 mA), and operating temperature (-40°C to 125°C). Selection depends on tolerance requirements for the application.

Q: Why does AS431IAZTR-G1 have lower cathode current (50 µA) compared to other substitutes?

A: Lower cathode current indicates reduced quiescent current consumption, beneficial for battery-powered or low-power applications. The AS431IAZTR-G1 maintains all other electrical specifications (2.5V to 36V output, 100 mA capacity, ±0.5% tolerance) while reducing standby power draw. This represents an enhancement over the original 1 mA cathode current specification.

Q: Is TL431AIZ (STMicroelectronics) compatible with the original TL431AILP footprint?

A: Yes. The TL431AIZ uses the identical TO-92-3 package with the same pinout as the TL431AILP. Through-hole mounting compatibility is maintained. The 2.495V output minimum is within the ±1% tolerance band of the 2.5V specification, ensuring functional equivalence in voltage reference applications.

Q: Can I substitute LT1431CZ#PBF for TL431AILP in all applications?

A: No. The LT1431CZ#PBF operates only to 70°C maximum temperature, while the TL431AILP supports 85°C. Applications requiring the full -40°C to 85°C range must use LT1431IZ#PBF instead, which extends to 85°C. Both offer ±0.4% tolerance and identical 30ppm/°C temperature coefficient.

Q: What is the significance of the ±0.4% tolerance in AZ431AZ-ATRG1 compared to the original ±1%?

A: The ±0.4% tolerance provides tighter voltage reference accuracy, reducing output voltage variation across the specified operating range. This enhancement benefits precision analog circuits requiring stable reference voltages. The part remains pin-compatible and functionally interchangeable while offering improved performance specifications.

Q: Why is KA431AZBU listed as a conditional alternative?

A: The KA431AZBU operates from -25°C to 85°C, not extending to the -40°C minimum of the original TL431AILP. It is suitable only for applications with relaxed low-temperature requirements. For designs requiring full -40°C operation, alternative parts with extended low-temperature ratings must be selected.

Q: Are all substitute parts ROHS3 compliant?

A: All recommended substitutes maintain ROHS3 compliance and MSL 1 (Unlimited) moisture sensitivity ratings, matching the original TL431AILP specifications. This ensures regulatory compatibility and environmental stability across all listed alternatives.

Q: What packaging formats are available for these shunt voltage reference ICs?

A: All listed substitutes are supplied in TO-92-3 through-hole packages with identical pinout and footprint compatibility. Packaging variants (Bulk, Cut Tape, Bag) reflect supplier distribution formats and do not affect electrical or mechanical compatibility. Component selection should prioritize electrical specifications and product status rather than packaging format.

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