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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > Voltage Reference

STMicroelectronics TL431AIZT

Name: TL431AIZT
Brand: STMicroelectronics
SKU: TL431AIZT
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: TL431AIZT

Manufacturer:: STMicroelectronics

Category:: Voltage Reference

Package:: TO-226-3, TO-92-3 (TO-226AA) Formed Leads

Datasheet:: TL431AIZT.pdf

Description:: IC VREF SHUNT ADJ 1% TO92-3

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Product details

Overview

TL431AIZT from STMicroelectronics is an AEC-Q100 qualified automotive-grade adjustable shunt voltage reference with 1% initial voltage accuracy, operating over −40 °C to +125 °C and supporting output voltages from 2.5 V to 36 V via two external resistors. It delivers 1–100 mA sink current capability with typical dynamic impedance of 0.22 Ω and is packaged in TO-92 (Z) for cost-sensitive, space-constrained power regulation in engine control units and body electronics.

For engineers reviewing the TL431AIZT datasheet, TL431AIZT pinout, TL431AIZT application, or TL431AIZT equivalent, this page provides verified technical context, validated pin functions, real-world automotive use cases, and confirmed alternative parts with documented functional differences - all grounded in ST's production datasheet DocID4467 Rev 17.

Technical Context

The TL431AIZT implements a precision 2.5 V bandgap reference core with internal error amplifier and NPN output stage, configured as a three-terminal shunt regulator. Its reference input (REF) compares against an internal 2.5 V threshold, controlling cathode current to maintain programmed output voltage across the anode–cathode terminals.

It operates in closed-loop shunt mode with guaranteed thermal stability across −40 °C to +125 °C, supports programmable output via resistor divider feedback, and maintains ≤1% V_REF tolerance at 25 °C with ≤30 mV total deviation over full temperature range - meeting automotive reliability requirements without external compensation.

Key Specifications

Parameter	Value and Actual Design Meaning
V_REF Accuracy	1% at 25 °C - ensures ±25 mV absolute reference error for precise feedback in regulated power supplies.
Output Voltage Range	2.5 V to 36 V - set externally with two resistors, enabling flexible design of isolated flyback, buck-derived, or linear post-regulator outputs.
Sink Current Range	1 mA to 100 mA - supports direct drive of optocoupler LEDs or low-power error amplifiers without external buffering.
Dynamic Impedance	0.22 Ω typical - minimizes output voltage variation under load transients, critical for stable feedback in switching converters.
Temp. Range	−40 °C to +125 °C - qualified per AEC-Q100 Grade 1, suitable for under-hood automotive applications including EPS and HVAC control modules.
Reference Input Current	≤4 µA max - reduces divider network power loss and enables high-resistance programming (e.g., 100 kΩ/10 kΩ) without accuracy degradation.
Off-State Cathode Current	≤500 nA - ensures minimal leakage when disabled, preserving battery-backed system states in always-on vehicle networks.

Pinout & Package

TL431AIZT uses the TO-92 plastic package (Z suffix), with standardized pinout viewed from top: Pin 1 = Anode, Pin 2 = Cathode, Pin 3 = Reference (REF). This through-hole package supports manual assembly and reflow-compatible lead tinning, with thermal resistance R_thJA = 200 °C/W enabling operation up to 150 °C junction temperature at ≤100 mA.

Pin/Terminal	Circuit Role	Design Meaning
Anode (Pin 1)	Current return path	Connected to system ground or low-side return; sets cathode-to-anode voltage (V_KA) compliance limit (max 37 V).
Cathode (Pin 2)	Regulated output node	Sinks current to maintain programmed V_OUT; directly drives optocoupler anodes or error amplifier inputs in isolated SMPS feedback loops.
Reference (Pin 3)	Feedback sense input	Compares external resistor divider voltage against internal 2.5 V reference; draws ≤4 µA, enabling high-impedance programming networks.

Key Features

Feature	Design Value
AEC-Q100 qualification	Grade 1 (−40 °C to +125 °C), certified for automotive powertrain and chassis systems requiring zero-defect reliability.
Adjustable 2.5–36 V output	Programmed with two external resistors - eliminates need for multiple fixed-voltage references in multi-rail designs.
0.22 Ω dynamic impedance	Enables <10 mV output shift under 10 mA load step - critical for maintaining tight regulation in DC-DC converter feedback paths.
1 mA minimum cathode current	Ensures stable regulation down to ultra-low-power modes (e.g., sleep-state biasing in body control modules).
≤500 nA off-state current	Permits use in battery-critical applications (e.g., telematics backup power) without measurable standby drain.

Applications

Engine Control Unit (ECU) Power Monitoring

Automotive Infotainment DC-DC Feedback

Use Scenario: Monitors 5 V rail integrity in gasoline/diesel ECU mainboard during cranking and cold-start conditions.

IC Role / Device Role / Timing Role: Shunt reference providing precision feedback to primary controller's analog monitoring circuitry.

Use Value: Maintains ±1% voltage threshold detection across −40 °C to +125 °C, preventing false undervoltage faults during transient load dumps.

Use Scenario: Sets regulated 3.3 V output for SoC I/O supply in head-unit power tree using isolated flyback topology.

IC Role / Device Role / Timing Role: Secondary-side shunt regulator driving optocoupler LED to close isolation loop with primary PWM controller.

Use Value: 0.22 Ω dynamic impedance ensures <±5 mV output deviation during 100 mA load steps, preserving display interface signal integrity.

Body Control Module (BCM) Linear Regulator

Electric Power Steering (EPS) Sensor Bias

Use Scenario: Generates stable 2.5 V reference for analog sensor signal conditioning (e.g., ambient light, door position) in BCM.

IC Role / Device Role / Timing Role: Precision voltage source feeding ADC reference input and op-amp bias networks.

Use Value: 1% initial accuracy and ≤30 mV tempco ensure <0.5% total measurement error over full automotive temperature range.

Use Scenario: Supplies calibrated 5 V bias to torque and angle sensors in EPS motor control unit.

IC Role / Device Role / Timing Role: Programmable shunt reference delivering low-noise, thermally stable excitation voltage.

Use Value: ≤500 nA off-state current prevents battery drain during vehicle sleep mode; AEC-Q100 qualification guarantees field reliability.

Equivalent & Alternatives

The following parts are listed as comparable options for similar adjustable shunt reference applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
TL431ACZ	Same TO-92 package, 1% accuracy, but commercial temp range (0 °C to +70 °C); no AEC-Q100 qualification.	Restricted to non-automotive industrial or consumer power supplies where extended temperature operation is not required.	Select only for cost-sensitive non-automotive designs with ambient temperature <70 °C and no vibration/shock certification needed.
TL432AIL3T	SOT23-3 package, same 1% accuracy and −40 °C to +125 °C range, but includes integrated precision resistor divider (R1/R2 = 10 kΩ/10 kΩ) for fixed 5 V output.	Eliminates external resistors for 5 V applications but sacrifices voltage adjustability; smaller footprint than TO-92.	Choose when board space is constrained and fixed 5 V output suffices - avoids layout complexity of external divider while retaining automotive qualification.

Compared with TL431AIZT, TL431ACZ lacks automotive qualification and thermal range, limiting its use outside benign environments; TL432AIL3T trades adjustability for integration and size reduction, making it optimal for compact 5 V-only designs where resistor count must be minimized.

Availability

TL431AIZT is available at Aetrix Electronics and suitable for automotive power monitoring, infotainment DC-DC feedback, and body control module linear regulation requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for TL431AIZT includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing microcontrollers, power ICs, sensors, and analog components for automotive, industrial, and consumer markets.

TL431AIZT belongs to ST's automotive-qualified voltage reference product line, engineered specifically for robust, high-precision feedback in safety-critical vehicle subsystems where thermal stability and long-term reliability are mandatory.

FAQ

What is the maximum cathode-to-anode voltage for TL431AIZT?

The absolute maximum cathode-to-anode voltage (V_KA) is 37 V, as specified in Table 1 of ST's DocID4467 Rev 17. Operation above this voltage risks permanent device failure. For 36 V nominal systems, derating to ≤34 V is recommended to ensure margin under transients like load dump.

Can TL431AIZT replace TL431CZ in an existing design?

TL431AIZT can replace TL431CZ only if the application requires −40 °C to +125 °C operation and AEC-Q100 qualification. Electrically, both share identical pinout, 1% accuracy, and TO-92 packaging, but TL431CZ is rated for 0 °C to +70 °C and lacks automotive qualification - unsuitable for under-hood deployment.

Does TL431AIZT require external capacitors for stability?

No external capacitor is required for basic shunt operation, but a 1 nF ceramic capacitor between REF and ANODE is recommended when driving capacitive loads >100 pF (e.g., long PCB traces to optocouplers) to prevent oscillation, per Figure 21 in the datasheet.

How does the 1% accuracy specification apply across temperature?

The 1% refers to initial accuracy at 25 °C. Total reference voltage deviation over −40 °C to +125 °C is ≤30 mV (±12 mV typical), as stated in Table 5 for TL431AI/TL432AI variants - meaning worst-case V_REF remains within 2.47 V to 2.53 V across the full automotive range.

TL431AIZT Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Package/Case:: TO-226-3, TO-92-3 (TO-226AA) Formed Leads

Series:: -

Packaging:: Tape & Reel (TR)

Product Status:: Active

Reference Type:: Shunt

Output Type:: Adjustable

Voltage - Output (Min/Fixed):: 2.495V

Voltage - Output (Max):: 36 V

Current - Output:: 100 mA

Tolerance:: ±1%

Temperature Coefficient:: -

Noise - 0.1Hz to 10Hz:: -

Noise - 10Hz to 10kHz:: -

Voltage - Input:: -

Current - Supply:: -

Current - Cathode:: 700 µA

Operating Temperature:: -40°C ~ 105°C (TA)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-92-3

TL431AIZT FAQ

1.How can I place an order for TL431AIZT through Aetrix?

Please submit a Request for Quotation (RFQ) for TL431AIZT on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for TL431AIZT reliable?

The price and inventory of TL431AIZT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for TL431AIZT is usually 5 days.

3.What payment methods are accepted for TL431AIZT?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for TL431AIZT transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for TL431AIZT?

TL431AIZT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your TL431AIZT order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for TL431AIZT?

For technical support, including TL431AIZT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your TL431AIZT requirements.

6.How does Aetrix verify that TL431AIZT is sourced from the original manufacturer or authorized distributors?

All TL431AIZT products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that TL431AIZT meets industry standards.

7.What is the process for return or replacement of TL431AIZT?

All TL431AIZT units undergo pre-shipment inspection (PSI). If there is an issue with TL431AIZT, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The TL431AIZT part is unused and in its original packaging.

Return procedure for TL431AIZT:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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