TL431BQLPRE3 Equivalent & Substitute Parts

Part Overview

The TL431BQLPRE3 is a shunt voltage reference IC manufactured by Texas Instruments, designed for adjustable voltage regulation applications. This component provides a fixed reference voltage of 2.495V with a maximum output of 36V and supports output currents up to 100 mA. The device is packaged in TO-92-3 (TO-226-3) through-hole configuration.

The TL431BQLPRE3 is classified as obsolete, which necessitates identification of active equivalent and substitute parts for new designs and ongoing production requirements. Active alternatives maintain the core functional specifications while offering improved availability and extended product lifecycle 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	±0.5%
Current - Cathode	700 µA
Operating Temperature	-40°C ~ 125°C (TA)
Mounting Type	Through Hole
Package / Case	TO-226-3, TO-92-3 (TO-226AA) Formed Leads
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution eligibility for the TL431BQLPRE3 is determined by the following critical parameters:

Reference Type & Output Type: All substitutes must maintain shunt reference architecture with adjustable output capability
Voltage Range: Output voltage minimum must be 2.495V or lower; maximum must be 36V or higher
Current Rating: Output current must support 100 mA minimum
Tolerance: ±0.5% tolerance is the baseline specification; tighter tolerances (±0.4%) are acceptable; looser tolerances (±0.8%, ±1%) represent functional alternatives with reduced precision
Package Compatibility: TO-92-3 or TO-92 through-hole packages ensure mechanical and electrical compatibility
Temperature Range: Operating range of -40°C to 125°C is required for industrial applications
Compliance: ROHS3 compliance and EAR99 classification are mandatory for regulatory alignment

Substitute parts are grouped by tolerance specification, as this parameter directly impacts circuit precision requirements and application suitability.

Parameter Comparison

Part Number	Manufacturer	Product Status	Voltage Min/Fixed (V)	Voltage Max (V)	Current Output (mA)	Tolerance	Cathode Current (µA/mA)	Temp Range (°C)	Package
TL431BQLPRE3	Texas Instruments	Obsolete	2.495	36	100	±0.5%	700 µA	-40 ~ 125	TO-92-3
TL431BQLPR	Texas Instruments	Active	2.495	36	100	±0.5%	700 µA	-40 ~ 125	TO-92-3
AS431AZTR-E1	Diodes Incorporated	Active	2.5	36	100	±0.5%	1 mA	-40 ~ 125	TO-92
AS431AZTR-G1	Diodes Incorporated	Active	2.5	36	100	±0.5%	1 mA	-40 ~ 125	TO-92
AS431BZTR-E1	Diodes Incorporated	Active	2.5	36	100	±1%	1 mA	-40 ~ 125	TO-92
AS431BZTR-G1	Diodes Incorporated	Active	2.5	36	100	±1%	1 mA	-40 ~ 125	TO-92
AS431IAZTR-G1	Diodes Incorporated	Active	2.5	36	100	±0.5%	50 µA	-40 ~ 125	TO-92
AZ431AZ-ATRE1	Diodes Incorporated	Active	2.5	36	100	±0.4%	1 mA	-40 ~ 125	TO-92
AZ431AZ-ATRG1	Diodes Incorporated	Active	2.5	36	100	±0.4%	1 mA	-40 ~ 125	TO-92
AZ431BZ-ATRE1	Diodes Incorporated	Active	2.5	36	100	±0.8%	1 mA	-40 ~ 125	TO-92
KA431AZTA	onsemi	Active	2.495	36	100	±1%	1 mA	-25 ~ 85	TO-92-3

Engineering Selection Recommendations

Primary Recommendation: TL431BQLPR

The TL431BQLPR is the direct active equivalent from Texas Instruments. It maintains identical electrical specifications (2.495V minimum output, ±0.5% tolerance, 700 µA cathode current) and package configuration (TO-92-3). This part is currently in active production status with 12,800 units in stock, ensuring supply continuity and design compatibility without circuit modification.

Secondary Recommendations by Tolerance Class:

±0.5% Tolerance (Precision Applications):

AS431AZTR-E1 and AS431AZTR-G1 (Diodes Incorporated): Both maintain ±0.5% tolerance with 2.5V minimum output and TO-92 packaging. Higher inventory availability (117,200 and 150,200 units respectively) supports volume production. Cathode current is 1 mA versus 700 µA in the original design.
AS431IAZTR-G1 (Diodes Incorporated): Offers ±0.5% tolerance with reduced cathode current (50 µA), beneficial for low-power applications. 56,350 units available.

±0.4% Tolerance (Enhanced Precision):

AZ431AZ-ATRE1 and AZ431AZ-ATRG1 (Diodes Incorporated): Provide tighter ±0.4% tolerance specification, suitable for applications requiring enhanced voltage reference accuracy. Inventory exceeds 1.3 million units, ensuring long-term availability.

±0.8% to ±1% Tolerance (General Purpose):

AS431BZTR-E1 and AS431BZTR-G1 (Diodes Incorporated): ±1% tolerance variants with 92,400 and 314,400 units in stock respectively.
AZ431BZ-ATRE1 (Diodes Incorporated): ±0.8% tolerance with 875,400 units available.
KA431AZTA (onsemi): ±1% tolerance in TO-92-3 package matching the original form factor. Operating temperature range is -25°C to 85°C, which is narrower than the original -40°C to 125°C specification.

Compliance Status: All recommended substitutes are ROHS3 compliant and classified as EAR99, maintaining regulatory alignment with the original part.

Frequently Asked Questions (FAQ)

Q: Can I use AS431 series parts as direct replacements for TL431BQLPRE3?

A: Yes, AS431 series parts from Diodes Incorporated are functionally equivalent. They maintain the same shunt reference architecture, adjustable output type, 2.5V minimum voltage, 36V maximum voltage, and 100 mA output current. The primary differences are cathode current specifications (1 mA versus 700 µA) and tolerance grades. Circuit operation remains compatible in standard applications.

Q: What is the significance of tolerance differences (±0.4%, ±0.5%, ±0.8%, ±1%)?

A: Tolerance specifies the accuracy of the reference voltage output. The TL431BQLPRE3 specifies ±0.5% tolerance. Tighter tolerances (±0.4%) provide higher precision for applications requiring strict voltage regulation. Looser tolerances (±0.8%, ±1%) are acceptable for general-purpose applications where voltage accuracy is less critical. Selection depends on circuit requirements and acceptable voltage deviation.

Q: Are TO-92 and TO-92-3 packages mechanically interchangeable?

A: TO-92 and TO-92-3 are both through-hole packages with three leads in identical physical configuration (TO-226-3 / TO-226AA). They are mechanically and electrically interchangeable on PCBs designed for standard TO-92 through-hole mounting. No PCB redesign is required for package substitution.

Q: Why do some substitutes have different cathode current specifications?

A: Cathode current (minimum operating current) varies by manufacturer design. The TL431BQLPRE3 specifies 700 µA, while most Diodes Incorporated alternatives specify 1 mA. AS431IAZTR-G1 specifies 50 µA for low-power applications. These differences affect minimum load requirements but do not impact voltage reference accuracy or output current capability in standard circuit configurations.

Q: Is KA431AZTA from onsemi a suitable replacement?

A: KA431AZTA is functionally compatible with matching 2.495V minimum output and TO-92-3 package. However, its operating temperature range (-25°C to 85°C) is narrower than the original specification (-40°C to 125°C). Use this part only in applications where the reduced temperature range is acceptable.

Q: What inventory considerations should guide part selection?

A: TL431BQLPR offers the most direct equivalent with 12,800 units in stock. For higher volume requirements, AZ431AZ-ATRE1 (1.3+ million units) and AS431BZTR-G1 (314,400 units) provide superior supply security. Diodes Incorporated parts generally offer higher inventory levels than Texas Instruments alternatives.

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