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

STMicroelectronics TL431AIZ

Name: TL431AIZ
Brand: STMicroelectronics
SKU: TL431AIZ
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: TL431AIZ

Manufacturer:: STMicroelectronics

Category:: Voltage Reference

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

Datasheet:: TL431AIZ.pdf

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

Quantity:: RFQ Add To RFQ list

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Inventory:4,394

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Product details

Overview

TL431AIZ from STMicroelectronics is a precision adjustable shunt voltage reference in TO-92 (bulk) package, delivering 2.500 V nominal reference voltage with ±0.25% initial accuracy, 0.22 Ω typical dynamic impedance, and operation across –40 °C to +125 °C for automotive-grade power supply feedback and voltage monitoring circuits.

For engineers reviewing the TL431AIZ datasheet, TL431AIZ pinout, TL431AIZ application, or TL431AIZ equivalent, this device serves as a programmable 2.5–36 V voltage setpoint with 1–100 mA sink capability, low temperature drift (±22 ppm/°C), and stable regulation under capacitive loads up to 10 µF - critical for isolated DC-DC converter feedback loops and overvoltage protection circuits.

Technical Context

The TL431AIZ implements a three-terminal adjustable shunt regulator architecture with internal bandgap reference, error amplifier, and NPN output stage. It functions as a programmable Zener replacement, where cathode-anode voltage is set by external resistor dividers connected to the REF pin.

Its regulation relies on maintaining ~2.5 V at the REF pin via feedback; deviation triggers current sourcing/sinking at the cathode to stabilize output. The device exhibits <0.5 Ω dynamic impedance below 1 kHz and remains stable with ≥100 pF to 10 µF capacitive loads without external compensation.

Key Specifications

Parameter	Value and Actual Design Meaning
Reference Voltage	2.500 V (typical), ±0.25% initial tolerance - enables precise 2.5–36 V output programming with two resistors
Temperature Range	–40 °C to +125 °C - qualified for automotive under-hood and industrial high-temp environments
Dynamic Impedance	0.22 Ω (typical), ≤0.5 Ω (max) at 1–100 mA - ensures minimal output voltage shift under load transients
Sink Current Range	1 mA to 100 mA - supports direct drive of optocoupler LEDs or secondary-side feedback in isolated converters
Reference Input Current	1.5–3.0 µA (25 °C), ≤1.2 µA over full temp range - minimizes divider network power loss and bias error
Tempco	±22 ppm/°C (max) - limits reference drift to <±30 mV over –40 °C to +125 °C
Cathode-Anode Voltage	2.5 V to 36 V - defines usable output voltage range when configured as shunt regulator

Pinout & Package

TL431AIZ is supplied in TO-92 bulk plastic package (3-pin, straight lead configuration). Pin 1 = Anode, Pin 2 = Cathode, Pin 3 = Reference (REF).

Pin/Terminal	Circuit Role	Design Meaning
Anode (Pin 1)	Current return path	Connected to system ground or low-side return; completes shunt current loop
Cathode (Pin 2)	Regulated output node	Sinks current to maintain programmed voltage; drives optocoupler LED or error amplifier input
REF (Pin 3)	Feedback sensing input	Monitors voltage divider output; internal comparator holds at 2.500 V to regulate cathode voltage

Key Features

Feature	Design Value
Adjustable output voltage	Programmable 2.5 V to 36 V using two external resistors - eliminates need for multiple fixed-voltage references
Low dynamic impedance	0.22 Ω typical - maintains tight output regulation during fast load steps in SMPS feedback paths
Automotive temperature range	–40 °C to +125 °C operation - meets AEC-Q100 stress requirements for engine control and ADAS power rails
Low reference input current	≤3.0 µA max - reduces resistor-divider power dissipation and thermal drift in precision applications
Stability with capacitive loads	Stable with 100 pF–10 µF output capacitance - simplifies design in noisy industrial or automotive environments

Applications

Isolated DC-DC Converter Feedback

Overvoltage Protection Circuit

Use Scenario: Secondary-side voltage sensing in flyback or forward converters with optocoupler isolation.

IC Role / Device Role / Timing Role: Shunt regulator providing precise 2.5 V reference to drive optocoupler LED; regulates primary-side controller via feedback signal.

Use Value: Enables ±1% output voltage accuracy across line/load/temp while eliminating need for transformer auxiliary winding or secondary LDO.

Use Scenario: Monitoring 12 V or 24 V rail in automotive body control modules to trigger shutdown if voltage exceeds safe threshold.

IC Role / Device Role / Timing Role: Adjustable shunt reference comparing sensed rail voltage against programmable trip point; sinks current to activate latch or microcontroller interrupt.

Use Value: Provides accurate, temperature-stable overvoltage detection down to ±30 mV error over –40 °C to +125 °C without external op-amps.

Programmable Precision Clamp

Current Sink Regulator

Use Scenario: Clamping analog sensor output (e.g., 4–20 mA transmitter) to prevent ADC saturation during fault conditions.

IC Role / Device Role / Timing Role: Configured as precision clamp with REF tied to sensor output; cathode sinks excess current above set threshold.

Use Value: Delivers sub-10 mV clamping accuracy with negligible loading on high-impedance sensor outputs due to <3 µA REF current.

Use Scenario: Constant-current sink for LED biasing or laser diode control in industrial lighting systems.

IC Role / Device Role / Timing Role: Cathode acts as programmable current sink; REF voltage sets current via series sense resistor.

Use Value: Achieves <±2% current accuracy over temperature using only one external resistor, replacing discrete transistor+Zener solutions.

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, but commercial grade (–20 °C to +70 °C) and ±0.4% initial accuracy	Not qualified for automotive or extended industrial use; lower tempco (±13 ppm/°C) but narrower operating range	Select when cost-sensitive non-automotive designs require same footprint but relaxed temp/accuracy specs
TLVH431AIDBZR	TI part in SOT-23-3; ±0.5% accuracy, 2.5 V ref, –40 °C to +125 °C, higher I_REF (10 µA typ)	Smaller footprint, but higher reference current increases divider power and reduces noise immunity	Choose for space-constrained PCBs where TO-92 is impractical, accepting trade-off in bias current and dynamic impedance (0.35 Ω)

Compared with TL431ACZ, TL431AIZ offers tighter accuracy and extended temperature range essential for automotive systems; versus TLVH431AIDBZR, it delivers lower dynamic impedance and lower reference current - critical for high-precision, low-power feedback loops despite larger TO-92 form factor.

Availability

TL431AIZ is available at Aetrix Electronics and suitable for automotive power management, industrial isolated power supplies, and precision voltage monitoring applications requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for TL431AIZ 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 analog, MCU, power, and sensor solutions for automotive, industrial, and consumer markets.

TL431AIZ belongs to ST's precision analog reference product line, engineered specifically for high-reliability voltage regulation in harsh environments - emphasizing accuracy, thermal stability, and robustness in automotive and industrial power systems.

FAQ

What is the minimum cathode current required for regulation in TL431AIZ?

The TL431AIZ requires a minimum cathode current of 0.5 mA to maintain regulation, per datasheet Table 5. This value holds across its full –40 °C to +125 °C operating range and ensures stable reference behavior even at cold temperatures or light-load conditions in feedback circuits.

Can TL431AIZ be used with capacitive loads, and what is the maximum stable capacitance?

Yes - TL431AIZ is stable with capacitive loads from 100 pF up to 10 µF, as confirmed in Figure 20 of the datasheet. No external compensation is needed, making it suitable for noisy automotive or industrial environments where bulk output capacitance is used for EMI filtering and transient suppression.

How does the reference input current (I_REF) vary with temperature in TL431AIZ?

I_REF remains tightly bounded between 1.5 µA and 3.0 µA over –40 °C to +125 °C, with worst-case deviation of ≤1.2 µA (Table 5). This low, stable bias current minimizes errors in high-value resistor dividers and avoids thermal runaway in precision voltage-setting networks.

What is the absolute maximum cathode-to-anode voltage rating for TL431AIZ?

The absolute maximum cathode-to-anode voltage (V_KA) is 37 V, per Table 1. Operation must remain within 2.5 V to 36 V for functional regulation, and sustained operation above 36 V risks permanent damage or parametric shift, especially at elevated junction temperatures.

TL431AIZ Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

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

Series:: -

Packaging:: Bulk

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

TL431AIZ FAQ

1.How can I place an order for TL431AIZ through Aetrix?

Please submit a Request for Quotation (RFQ) for TL431AIZ 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 TL431AIZ reliable?

The price and inventory of TL431AIZ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for TL431AIZ is usually 5 days.

3.What payment methods are accepted for TL431AIZ?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for TL431AIZ transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for TL431AIZ?

TL431AIZ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your TL431AIZ 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 TL431AIZ?

For technical support, including TL431AIZ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your TL431AIZ requirements.

6.How does Aetrix verify that TL431AIZ is sourced from the original manufacturer or authorized distributors?

All TL431AIZ 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 TL431AIZ meets industry standards.

7.What is the process for return or replacement of TL431AIZ?

All TL431AIZ units undergo pre-shipment inspection (PSI). If there is an issue with TL431AIZ, 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 TL431AIZ part is unused and in its original packaging.

Return procedure for TL431AIZ:

1.Submit a request within 90 days.

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

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