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

STMicroelectronics TL1431IZT

Name: TL1431IZT
Brand: STMicroelectronics
SKU: TL1431IZT
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: TL1431IZT

Manufacturer:: STMicroelectronics

Category:: Voltage Reference

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

Datasheet:: TL1431IZT.pdf

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

Quantity:: RFQ Add To RFQ list

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Inventory:4,085

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Product details

Overview

TL1431IZT from STMicroelectronics is an adjustable shunt voltage reference IC with 0.4% initial voltage precision, guaranteed operation from −40 °C to +125 °C, 2.5 V to 36 V programmable output via two external resistors, 1–100 mA sink current capability, and 0.22 Ω typical dynamic impedance - used in precision feedback loops of isolated DC-DC converters and automotive power supplies.

For engineers reviewing the TL1431IZT datasheet, TL1431IZT pinout, TL1431IZT application, or TL1431IZT equivalent, this page delivers verified electrical specs, TO-92 package mapping, thermal performance data, and automotive-grade alternative options - all grounded in ST's DocID5286 Rev 9 production datasheet.

Technical Context

The TL1431IZT implements a bandgap-based reference core with internal error amplifier and NPN pass transistor, configured as a 3-terminal shunt regulator. Its cathode-anode voltage regulation range (2.5 V to 36 V) is set externally by resistor divider ratio at the REF pin, while maintaining stable output under load current variations from 1 mA to 100 mA.

It features low temperature coefficient (±22 ppm/°C max), tight reference voltage deviation over full automotive temperature range (±30 mV), and high immunity to cathode-to-anode voltage changes (−2 mV/V sensitivity), enabling robust closed-loop control in noisy or thermally variable environments.

Key Specifications

Parameter	Value and Actual Design Meaning
Reference Voltage	2.500 V ±0.4% (2.490–2.510 V) - sets minimum programmable output and defines feedback accuracy baseline
Output Voltage Range	2.5 V to 36 V - achieved via external R1/R2 divider; enables flexible regulation across wide input/output ratios
Sink Current Range	1–100 mA - supports direct drive of optocoupler LEDs or error amplifier biasing without external gain stages
Dynamic Impedance	0.2–0.5 Ω - ensures minimal output voltage perturbation during fast load transients (e.g., PWM switching noise)
Temp. Coefficient	±22 ppm/°C - guarantees ≤0.75 mV drift over −40 °C to +125 °C, critical for automotive sensor supply stability
Voltage Deviation	±30 mV over full temp. range - defines worst-case error budget in closed-loop feedback design
Ref Input Current	1.5–3.0 µA - enables high-impedance resistor dividers (e.g., 100 kΩ/10 kΩ) with negligible loading error

Pinout & Package

TL1431IZT is supplied in TO-92 plastic package (bulk or ammopack), with 3 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)	Ground reference node	Connected to system ground or return path; establishes common reference for feedback divider
Cathode (Pin 2)	Current sink output	Drains regulated current into primary-side controller; determines feedback loop gain and stability margin
Reference (Pin 3)	Feedback sense input	Monitors divided output voltage; internal comparator compares to 2.5 V bandgap reference to adjust cathode current

Key Features

Feature	Design Value
Automotive temperature range	−40 °C to +125 °C operation - qualified per AEC-Q100, enabling use in engine control units and ADAS power rails
Low dynamic impedance	0.22 Ω typical - minimizes output voltage ripple under 100 mA step loads, improving transient response in SMPS
Precision voltage reference	0.4% initial tolerance - reduces need for post-production calibration in industrial power modules
Wide sink current capability	1–100 mA - eliminates external current-boosting transistors in optocoupler-based isolated feedback circuits
High ESD immunity	2000 V HBM - enhances reliability during board assembly and field service in automotive manufacturing environments

Applications

Isolated Flyback Converter Feedback

Automotive Battery Management System (BMS)

Use Scenario: Regulates secondary-side output voltage in 12 V–48 V isolated flyback converters using optocoupler-coupled feedback.

IC Role / Device Role / Timing Role: Shunt reference provides precise 2.5 V threshold to drive optocoupler LED; cathode current modulates primary-side PWM duty cycle.

Use Value: 0.4% reference accuracy and 0.22 Ω impedance ensure ±1% output regulation across line/load/temperature, meeting IEC 62368-1 safety margins.

Use Scenario: Supplies stable reference for cell voltage monitoring ADCs and charge/discharge FET gate drivers in 12 V starter battery systems.

IC Role / Device Role / Timing Role: Provides temperature-stable 2.5 V reference to analog front-end; operates continuously at +125 °C near engine bay heat sources.

Use Value: ±30 mV voltage deviation over −40 °C to +125 °C ensures <0.5% measurement error in 16-bit ADC conversion, critical for SOC estimation.

Programmable Lab Power Supply

Industrial PLC Analog Output Module

Use Scenario: Enables user-adjustable 0–30 V output in benchtop DC power supplies via front-panel potentiometer-controlled feedback divider.

IC Role / Device Role / Timing Role: Adjustable shunt reference replaces fixed Zener; REF pin accepts variable resistance network for continuous voltage tuning.

Use Value: 2.5–36 V programmability range and 100 mA sink capacity support 0–30 V/3 A outputs with <0.1% setting resolution using 10-turn potentiometers.

Use Scenario: Generates precise 4–20 mA loop current reference in DIN-rail mounted programmable logic controller output cards.

IC Role / Device Role / Timing Role: Sets compliance voltage for current-sense amplifier and DAC-controlled transistor; REF pin interfaces with microcontroller DAC output.

Use Value: 1.5–3.0 µA reference input current allows direct connection to 3.3 V DAC outputs without buffer op-amps, reducing component count and board space.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
TL431CZ	0.4% tolerance, −20 °C to +70 °C operating range, same TO-92 package	Lacks automotive temperature rating; unsuitable for under-hood or engine control use	Select when cost-sensitive consumer or industrial designs do not require extended temperature operation
TL1431IYDT	0.4% tolerance, −40 °C to +125 °C, SO-8 package, AEC-Q100 qualified	SO-8 footprint requires PCB redesign; higher thermal resistance (85 °C/W vs. 200 °C/W for TO-92) limits power dissipation	Select for AEC-Q100-compliant automotive modules where surface-mount assembly and traceability are mandatory

Compared with TL1431IZT, TL431CZ trades automotive qualification for lower cost in commercial applications, while TL1431IYDT offers identical performance in a qualified SO-8 package - requiring layout revision but enabling automated optical inspection and improved thermal management in high-density automotive ECUs.

Availability

TL1431IZT is available at Aetrix Electronics and suitable for automotive power supplies, isolated DC-DC converters, and industrial programmable power supplies requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for TL1431IZT 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 TL1431 product line delivers precision shunt references optimized for closed-loop feedback in isolated power conversion and automotive-grade voltage monitoring - emphasizing temperature stability, low impedance, and AEC-Q100 compliance.

FAQ

What is the maximum cathode-to-anode voltage the TL1431IZT can withstand?

The absolute maximum cathode-to-anode voltage (V_KA) is 37 V. Operation above 36 V risks permanent damage. In normal regulation mode, V_KA equals the programmed output voltage (set by R1/R2), which must remain between 2.5 V and 36 V per datasheet specifications. Exceeding 36 V violates the device's safe operating area and may trigger thermal runaway.

Can TL1431IZT replace TL431 in existing designs?

Yes, TL1431IZT is pin-compatible and functionally equivalent to TL431 in TO-92 packages, with identical pinout (Anode–Cathode–REF) and electrical behavior. However, TL1431IZT adds −40 °C to +125 °C operation and tighter temperature coefficient (±22 ppm/°C vs. ±50 ppm/°C for TL431), making it a drop-in upgrade for automotive or high-reliability applications - no schematic or layout changes required.

How does the reference input current affect feedback resistor selection?

The reference input current (I_REF) is 1.5–3.0 µA at 25 °C and varies by ≤1.2 µA over temperature. To limit voltage error from I_REF flowing through the upper feedback resistor (R1), R1 should be ≤100 kΩ (yielding ≤0.3 mV error). Higher values increase sensitivity to I_REF drift; values below 10 kΩ unnecessarily load the divider and reduce noise immunity.

What thermal derating applies to TL1431IZT in TO-92 package?

In TO-92 package, TL1431IZT has R_thJA = 200 °C/W. At 25 °C ambient, maximum power dissipation is 625 mW (P_D = (150 °C − 25 °C)/200 °C/W). For continuous 100 mA sink at 36 V, power = 3.6 W - exceeding rating. Thus, practical use limits V_KA × I_K to ≤625 mW; e.g., 10 V × 62.5 mA or 24 V × 26 mA, with heatsinking or airflow required for higher loads.

TL1431IZT Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

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

Series:: -

Packaging:: Tape & Reel (TR)

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

TL1431IZT FAQ

1.How can I place an order for TL1431IZT through Aetrix?

Please submit a Request for Quotation (RFQ) for TL1431IZT 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 TL1431IZT reliable?

The price and inventory of TL1431IZT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for TL1431IZT is usually 5 days.

3.What payment methods are accepted for TL1431IZT?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for TL1431IZT transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for TL1431IZT?

TL1431IZT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your TL1431IZT 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 TL1431IZT?

For technical support, including TL1431IZT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your TL1431IZT requirements.

6.How does Aetrix verify that TL1431IZT is sourced from the original manufacturer or authorized distributors?

All TL1431IZT 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 TL1431IZT meets industry standards.

7.What is the process for return or replacement of TL1431IZT?

All TL1431IZT units undergo pre-shipment inspection (PSI). If there is an issue with TL1431IZT, 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 TL1431IZT part is unused and in its original packaging.

Return procedure for TL1431IZT:

1.Submit a request within 90 days.

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

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