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

STMicroelectronics TL1431IZ

Name: TL1431IZ
Brand: STMicroelectronics
SKU: TL1431IZ
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: TL1431IZ

Manufacturer:: STMicroelectronics

Category:: Voltage Reference

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

Datasheet:: TL1431IZ.pdf

Description:: IC VREF SHUNT ADJ 0.4% TO92-3

Quantity:: RFQ Add To RFQ list

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Inventory:1,084

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Product details

Overview

TL1431IZ from STMicroelectronics is an adjustable shunt voltage reference IC with 0.4% initial voltage precision, guaranteed operation from −40 °C to +125 °C, 1–100 mA sink current capability, 0.22 Ω typical dynamic impedance, and programmable output from 2.5 V to 36 V using two external resistors - used in precision feedback loops of isolated DC-DC converters and automotive power supplies.

For engineers reviewing the TL1431IZ datasheet, TL1431IZ pinout, TL1431IZ application, or TL1431IZ equivalent, this page delivers verified technical context, TO-92 package pin mapping, automotive-grade thermal stability data, and real-world design value for closed-loop voltage regulation in safety-critical systems.

Technical Context

The TL1431IZ implements a bandgap-based reference amplifier driving an NPN output transistor in shunt configuration, enabling precise cathode-to-anode voltage control via external resistor divider on the REF pin. Its internal architecture supports stable operation with capacitive loads up to 10 µF and maintains regulation down to 0.5 mA minimum cathode current.

It features low temperature coefficient (±22 ppm/°C max), minimal line regulation error (−2 to −1.1 mV/V), and tight reference input voltage deviation (7–30 mV over full automotive temperature range), making it suitable for high-reliability feedback paths where drift must remain below ±0.5% across −40 °C to +125 °C.

Key Specifications

Parameter	Value and Actual Design Meaning
Reference Voltage	2.500 V nominal (2.490–2.510 V min/max at 25 °C); sets base accuracy for all programmable outputs.
Voltage Precision	0.4% over temperature (±7 mV ΔVref max from −40 °C to +125 °C); ensures stable setpoint in automotive environments.
Sink Current Range	1–100 mA cathode current; supports direct drive of optocoupler LEDs or error amplifier inputs without buffering.
Dynamic Impedance	0.2–0.5 Ω typical; enables fast transient response and low output noise in feedback networks.
Operating Temperature	−40 °C to +125 °C; qualified per AEC-Q100 for under-hood automotive applications.
Thermal Resistance	R_thJA = 200 °C/W (TO-92); defines maximum power dissipation limit (625 mW at T_amb = 25 °C).
ESD Rating	HBM 2000 V; provides robustness against handling and board-level electrostatic discharge events.

Pinout & Package

TL1431IZ is supplied in TO-92 plastic package (bulk or ammopack), with three leads: Anode (pin 1), Cathode (pin 2), and Reference (pin 3). Pin numbering follows standard TO-92 top-view orientation (flat side facing viewer, leads down).

Pin/Terminal	Circuit Role	Design Meaning
Anode (Pin 1)	Reference ground node	Connected to system ground or return path; forms reference potential for internal amplifier.
Cathode (Pin 2)	Current sink output	Delivers regulated current to external load (e.g., optocoupler LED); voltage at this pin equals programmed V_OUT.
Reference (Pin 3)	Feedback input	Monitors divided output voltage; internal comparator forces V_REF = 2.5 V, setting V_OUT = 2.5 × (1 + R1/R2).

Key Features

Feature	Design Value
Adjustable Output Range	2.5 V to 36 V via two-resistor divider - eliminates need for multiple fixed-reference parts in multi-rail designs.
Automotive Temperature Range	−40 °C to +125 °C operation with guaranteed specs - enables use in engine control units and ADAS power stages.
Low Dynamic Impedance	0.22 Ω typical - minimizes output voltage perturbation during load transients in isolated flyback feedback loops.
High Sink Current Capability	100 mA max cathode current - directly drives standard PC817/PC817x optocouplers without external transistor staging.
Stable with Capacitive Loads	Supports ≥10 µF output capacitance - simplifies EMI filtering and improves loop stability in noisy automotive environments.

Applications

Isolated DC-DC Converter Feedback

Automotive Battery Monitor

Use Scenario: Regulating output voltage of a 12 V-to-5 V flyback converter using optocoupler-coupled feedback.

IC Role / Device Role / Timing Role: Shunt reference providing precise 2.5 V threshold to control optocoupler LED current based on secondary-side voltage.

Use Value: Enables ±1% output regulation over line, load, and temperature while maintaining galvanic isolation and meeting AEC-Q100 requirements.

Use Scenario: Monitoring 12 V battery voltage in start-stop systems with microcontroller ADC input scaling.

IC Role / Device Role / Timing Role: Programmable reference generating stable 4.096 V for 12-bit ADC reference rail.

Use Value: Delivers <0.1% reference drift over −40 °C to +125 °C, improving SOC estimation accuracy by >2% vs. internal MCU reference.

Programmable Overvoltage Protection

Industrial Power Supply Trim

Use Scenario: Detecting >15.5 V battery overvoltage condition in commercial vehicle ECUs.

IC Role / Device Role / Timing Role: Adjustable threshold detector triggering shutdown logic when divided battery voltage exceeds 2.5 V at REF pin.

Use Value: Achieves ±0.05 V trip-point accuracy across temperature, reducing false trips and extending component lifetime.

Use Scenario: Fine-tuning output voltage of a 24 V industrial SMPS using digital potentiometer-controlled feedback divider.

IC Role / Device Role / Timing Role: High-stability reference enabling 10 mV resolution trimming over 22–26 V range.

Use Value: Maintains <±0.02% output drift during 8-hour continuous operation, critical for PLC analog I/O calibration.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
TL431BIDR	0.5% initial tolerance, −40 °C to +105 °C, R_thJA = 157 °C/W (SOT-23-5L); higher temp coefficient (±50 ppm/°C).	Limited to non-automotive industrial use; unsuitable for under-hood deployment above +105 °C.	Select when cost sensitivity outweighs extended temperature requirement and SMT assembly is preferred.
KA431AZ	0.4% tolerance, −20 °C to +70 °C, TO-92 only; no AEC-Q100 qualification; 0.3 Ω dynamic impedance.	Restricted to consumer/commercial power supplies; lacks automotive reliability screening and thermal margin.	Choose only for cost-driven non-automotive applications where ambient temperature stays below 70 °C.

Compared with TL431BIDR and KA431AZ, TL1431IZ uniquely combines AEC-Q100 qualification, +125 °C operation, and TO-92 through-hole compatibility - making it the sole option for legacy automotive designs requiring drop-in replacement of older TL431 variants without PCB redesign.

Availability

TL1431IZ is available at Aetrix Electronics and suitable for automotive power management, isolated DC-DC converter feedback, and industrial voltage monitoring requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for TL1431IZ 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, power, microcontroller, and sensor solutions for automotive, industrial, and consumer markets.

TL1431IZ belongs to ST's precision analog reference product line, engineered specifically for high-reliability feedback control in automotive and industrial power systems where long-term stability and temperature resilience are mandatory.

FAQ

What is the minimum cathode current required for regulation in TL1431IZ?

The TL1431IZ requires a minimum cathode current of 0.5 mA to maintain regulation, as specified in Table 4 of the datasheet under "Imin Minimum cathode current for regulation." This value holds across the full −40 °C to +125 °C operating range and ensures stable reference behavior even under light-load conditions in battery-powered systems.

Can TL1431IZ replace TL431 in existing designs?

Yes - TL1431IZ is pin-compatible with TL431 in TO-92 packages and shares identical electrical characteristics including reference voltage, sink current range, and dynamic impedance. However, TL1431IZ adds AEC-Q100 qualification and extended +125 °C operation, making it a direct upgrade for automotive applications without circuit modification.

How does the TL1431IZ handle capacitive loads on its cathode?

TL1431IZ remains stable with output capacitances up to 10 µF, as confirmed in Figure 20 of the datasheet. Its internal compensation allows safe operation with bulk electrolytic or ceramic capacitors commonly used in DC-DC output filters, eliminating need for external phase compensation in most feedback configurations.

What is the meaning of the 'Z' suffix in TL1431IZ?

The 'Z' suffix denotes TO-92 packaging in bulk or ammopack form, as defined in Table 15 of the datasheet. It distinguishes this variant from SO-8 ('D'), SOT-23-3L ('L3'), and SOT-23-5L ('L5') versions - all sharing identical electrical specs but differing in thermal performance and mounting method.

TL1431IZ Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

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

Series:: -

Packaging:: Bulk

Product Status:: Active

Reference Type:: Shunt

Output Type:: Adjustable

Voltage - Output (Min/Fixed):: 2.5V

Voltage - Output (Max):: 36 V

Current - Output:: 100 mA

Tolerance:: ±0.4%

Temperature Coefficient:: 100ppm/°C

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

TL1431IZ FAQ

1.How can I place an order for TL1431IZ through Aetrix?

Please submit a Request for Quotation (RFQ) for TL1431IZ 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 TL1431IZ reliable?

The price and inventory of TL1431IZ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for TL1431IZ is usually 5 days.

3.What payment methods are accepted for TL1431IZ?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for TL1431IZ transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for TL1431IZ?

TL1431IZ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your TL1431IZ 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 TL1431IZ?

For technical support, including TL1431IZ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your TL1431IZ requirements.

6.How does Aetrix verify that TL1431IZ is sourced from the original manufacturer or authorized distributors?

All TL1431IZ 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 TL1431IZ meets industry standards.

7.What is the process for return or replacement of TL1431IZ?

All TL1431IZ units undergo pre-shipment inspection (PSI). If there is an issue with TL1431IZ, 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 TL1431IZ part is unused and in its original packaging.

Return procedure for TL1431IZ:

1.Submit a request within 90 days.

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

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