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

STMicroelectronics TL431IZ-AP

Name: TL431IZ-AP
Brand: STMicroelectronics
SKU: TL431IZ-AP
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: TL431IZ-AP

Manufacturer:: STMicroelectronics

Category:: Voltage Reference

Package:: TO-226-2, TO-92-2 (TO-226AC)

Datasheet:: TL431IZ-AP.pdf

Description:: IC VREF SHUNT ADJ 2.21% TO92-3

Quantity:: RFQ Add To RFQ list

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Inventory:5,996

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Product details

Overview

TL431IZ-AP from STMicroelectronics is an AEC-Q100 qualified automotive-grade adjustable shunt voltage reference with 2% initial voltage accuracy, operating over −40 °C to +125 °C, supporting 1–100 mA sink current and delivering 0.22 Ω typical dynamic impedance for precision feedback in isolated DC-DC converters and battery management systems.

For engineers reviewing the TL431IZ-AP datasheet, TL431IZ-AP pinout, TL431IZ-AP application, or TL431IZ-AP equivalent, this page provides verified package mapping (TO-92), confirmed terminal roles (Anode/Cathode/Ref), temperature-stable reference performance, and direct substitution guidance for automotive power supply design.

Technical Context

The TL431IZ-AP implements a three-terminal programmable shunt regulator topology where the reference (Ref) pin senses voltage via external resistor dividers, the cathode sinks load current, and the anode connects to ground or return path. Its internal bandgap reference and error amplifier enable stable 2.5–36 V output programming across full automotive temperature range.

It operates as a high-gain transconductance amplifier with 0.22 Ω dynamic impedance below 1 kHz, maintaining ≤30 mV total reference voltage deviation over −40 °C to +125 °C and exhibiting −2.7 to −1.4 mV/V line regulation sensitivity across 10–36 V cathode-anode voltage swing.

Key Specifications

Parameter	Value and Actual Design Meaning
Reference Voltage	2.5 V nominal, ±2% tolerance at 25 °C - sets minimum programmable output voltage and defines divider ratio baseline.
Output Voltage Range	2.5 to 36 V - achieved using two external resistors; enables flexible feedback in flyback, forward, and buck-derived topologies.
Sink Current Range	1 to 100 mA - supports direct drive of optocoupler LEDs or secondary-side error amplifiers without external buffering.
Dynamic Impedance	0.22 Ω typical at 1–100 mA - ensures tight regulation under transient load changes in closed-loop SMPS feedback paths.
Temp. Range	−40 °C to +125 °C - validated for under-hood automotive applications including engine control units and ADAS power rails.
Voltage Deviation	≤30 mV over full temperature range - guarantees consistent loop gain and stability margin across environmental extremes.
Line Regulation	−2.7 to −1.4 mV/V - quantifies reference drift vs. input voltage variation, critical for wide-input-range industrial supplies.

Pinout & Package

TL431IZ-AP uses the TO-92 plastic package (3-lead, through-hole), with standardized lead configuration: Pin 1 = Anode, Pin 2 = Cathode, Pin 3 = Reference (Ref). Thermal resistance junction-to-ambient is 200 °C/W, requiring board-level thermal relief for >50 mA continuous operation.

Pin/Terminal	Circuit Role	Design Meaning
Anode (Pin 1)	Ground reference node	Return path for reference and error amplifier bias; must be low-impedance connection to system ground plane.
Cathode (Pin 2)	Current sink output	Drives optocoupler LED or feedback network; voltage at this pin equals programmed output minus divider drop.
Reference (Pin 3)	Feedback sense input	High-impedance (≤6.5 µA max) input that triggers regulation when voltage reaches 2.5 V; connected to resistor divider midpoint.

Key Features

Feature	Design Value
AEC-Q100 qualification	Validated for automotive use per stress test requirements - enables deployment in safety-critical power domains without additional qualification effort.
Adjustable 2.5–36 V output	Programmed via two external resistors - eliminates need for multiple fixed-voltage references and reduces BOM count in multi-rail systems.
0.22 Ω dynamic impedance	Enables <10 mV load regulation error at 100 mA step - maintains tight output tolerance in high-current auxiliary supplies.
−40 °C to +125 °C operation	Guaranteed performance across full automotive ambient range - supports placement near heat sources like power MOSFETs or transformers.
1–100 mA sink capability	Directly drives standard PC817/PC818 optocouplers - simplifies isolated feedback design without transistor buffers or level-shifting circuits.

Applications

Automotive DC-DC Converter

Industrial Isolated PSU

Use Scenario: Secondary-side voltage regulation in 12 V–48 V automotive buck-boost converters powering infotainment ECUs.

IC Role / Device Role / Timing Role: Shunt reference providing feedback signal to optocoupler-driven primary-side controller (e.g., UC384x).

Use Value: Maintains ±1.5% output accuracy over −40 °C to +125 °C ambient, meeting ASIL-B functional safety monitoring thresholds.

Use Scenario: Output voltage stabilization in DIN-rail mounted 24 V AC/DC power supplies for PLC I/O modules.

IC Role / Device Role / Timing Role: Precision shunt element in TL431-based feedback loop controlling TOPSwitch-JX primary-side controller.

Use Value: Delivers 0.22 Ω dynamic impedance to suppress 50 Hz ripple-induced instability during brownout conditions.

Battery Management System

Programmable Lab Power Supply

Use Scenario: Cell voltage reference in 12S LiFePO₄ battery pack monitor boards for EV charging stations.

IC Role / Device Role / Timing Role: Adjustable reference setting threshold for overvoltage protection comparators and cell balancing triggers.

Use Value: 2% accuracy and 30 mV tempco ensure consistent trip points across charge/discharge cycles and ambient shifts.

Use Scenario: Programmable voltage setpoint generator in benchtop 0–30 V/0–3 A linear power supplies.

IC Role / Device Role / Timing Role: High-stability reference source feeding DAC-controlled op-amp summing junction for analog voltage programming.

Use Value: 0.5 µA max reference input current minimizes DAC loading error, enabling <0.1% setpoint resolution.

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-AP	1% initial accuracy, same TO-92 package and −40 °C to +125 °C rating	Higher-precision feedback required in servo motor drives where 2.5 V reference drift must stay <±12.5 mV	Select when tighter initial tolerance justifies marginal cost increase and thermal derating remains acceptable.
TL432IZ-AP	Identical specs but includes internal 2.5 V reference bypass capacitor; same pinout and footprint	Reduces external decoupling needs in space-constrained automotive modules where PCB real estate limits capacitor placement	Choose when minimizing external components is prioritized over absolute lowest unit cost in high-volume telematics designs.

Compared with TL431IZ-AP, TL431ACZ-AP improves initial accuracy by 1% at no thermal or package penalty, while TL432IZ-AP integrates bypass capacitance to reduce layout sensitivity-both retain identical pin compatibility and automotive qualification.

Availability

TL431IZ-AP is available at Aetrix Electronics and suitable for automotive power supply, industrial isolated PSU, and battery management system designs requiring stable component supply with guaranteed AEC-Q100 compliance and long-term production continuity.

Supply support for TL431IZ-AP 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.

The TL431 product line delivers precision programmable shunt references optimized for feedback control in regulated power supplies, with automotive variants engineered specifically for under-hood reliability and extended temperature operation.

FAQ

What is the maximum cathode-to-anode voltage for TL431IZ-AP?

The absolute maximum cathode-to-anode voltage is 37 V. Operation above this risks permanent damage. In normal regulation, VKA is maintained between Vref (2.5 V) and 36 V per datasheet operating conditions - design margins should keep peak transients below 34 V with appropriate clamping.

Can TL431IZ-AP replace TL431CZ-AP in existing designs?

Yes, TL431IZ-AP is a direct drop-in replacement for TL431CZ-AP in terms of pinout, package, and electrical behavior, but extends the operating temperature range from 0 °C to +70 °C up to −40 °C to +125 °C and adds AEC-Q100 qualification - no circuit changes are needed for automotive upgrade paths.

How does the reference input current affect resistor divider design?

Iref is ≤6.5 µA over temperature, so a 10 kΩ upper resistor draws ≤65 µA - negligible compared to typical 100 µA–1 mA divider currents. However, using >100 kΩ resistors introduces measurable error due to Iref injection; ST recommends R1+R2 ≤ 50 kΩ for <0.1% accuracy loss.

Is TL431IZ-AP compatible with optocouplers commonly used in flyback converters?

Yes - its 1–100 mA sink capability directly drives standard PC817, PC818, and SFH615A optocouplers. At 5 mA LED current, typical cathode voltage is ~2.0 V, ensuring sufficient forward bias; dynamic impedance of 0.22 Ω prevents phase shift that could destabilize Type II compensation networks.

TL431IZ-AP Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Package/Case:: TO-226-2, TO-92-2 (TO-226AC)

Series:: -

Packaging:: Cut Tape (CT)

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:: ±2.21%

Temperature Coefficient:: -

Noise - 0.1Hz to 10Hz:: -

Noise - 10Hz to 10kHz:: -

Voltage - Input:: -

Current - Supply:: -

Current - Cathode:: 1 mA

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

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-92-3

TL431IZ-AP FAQ

1.How can I place an order for TL431IZ-AP through Aetrix?

Please submit a Request for Quotation (RFQ) for TL431IZ-AP 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 TL431IZ-AP reliable?

The price and inventory of TL431IZ-AP are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for TL431IZ-AP is usually 5 days.

3.What payment methods are accepted for TL431IZ-AP?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for TL431IZ-AP transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for TL431IZ-AP?

TL431IZ-AP orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your TL431IZ-AP 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 TL431IZ-AP?

For technical support, including TL431IZ-AP datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your TL431IZ-AP requirements.

6.How does Aetrix verify that TL431IZ-AP is sourced from the original manufacturer or authorized distributors?

All TL431IZ-AP 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 TL431IZ-AP meets industry standards.

7.What is the process for return or replacement of TL431IZ-AP?

All TL431IZ-AP units undergo pre-shipment inspection (PSI). If there is an issue with TL431IZ-AP, 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 TL431IZ-AP part is unused and in its original packaging.

Return procedure for TL431IZ-AP:

1.Submit a request within 90 days.

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

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