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

STMicroelectronics TL1431ACZ

Name: TL1431ACZ
Brand: STMicroelectronics
SKU: TL1431ACZ
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: TL1431ACZ

Manufacturer:: STMicroelectronics

Category:: Voltage Reference

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

Datasheet:: TL1431ACZ.pdf

Description:: IC VREF SHUNT ADJ 0.25% TO92-3

Quantity:: RFQ Add To RFQ list

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Inventory:4,099

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Product details

Overview

TL1431ACZ from STMicroelectronics is an adjustable shunt voltage reference IC with 0.25% initial voltage precision, guaranteed operation from −40 °C to +125 °C, and sink current capability from 1 mA to 100 mA. It sets output voltage between 2.5 V and 36 V using two external resistors and delivers typical dynamic impedance of 0.22 Ω - used in isolated flyback feedback loops, programmable power supplies, and automotive voltage monitoring circuits.

For engineers reviewing the TL1431ACZ datasheet, TL1431ACZ pinout, TL1431ACZ application, or TL1431ACZ equivalent, key selection criteria include temperature-stable reference accuracy (±0.25%), cathode current range (1–100 mA), TO-92 package thermal resistance (R_thJA = 200 °C/W), and automotive-grade operating range (−40 °C to +125 °C).

Technical Context

The TL1431ACZ implements a bandgap-based reference core with internal error amplifier and NPN pass transistor, configured as a three-terminal shunt regulator. Its regulation loop compares the REF pin voltage against an internal 2.500 V reference and adjusts cathode current to maintain setpoint voltage across external resistor dividers.

It operates in continuous conduction mode over its full 1–100 mA cathode current range, with dynamic impedance specified at ≤0.5 Ω (typ. 0.22 Ω) up to 1 kHz. Temperature coefficient is ±13 ppm/°C max, and reference input voltage deviation is limited to ±3 mV over −40 °C to +125 °C.

Key Specifications

Parameter	Value and Actual Design Meaning
Reference Voltage	2.493–2.507 V (0.25% tolerance at 25 °C); sets minimum output voltage threshold for external divider networks
Output Voltage Range	2.5 V to 36 V (adjustable via R1/R2 divider); enables flexible feedback design in DC-DC converters and LDOs
Cathode Current Range	1–100 mA (continuous); supports direct sinking into optocoupler LEDs or error amplifier inputs without external buffering
Dynamic Impedance	0.2–0.5 Ω (typ. 0.22 Ω at 1–100 mA, f ≤ 1 kHz); ensures stable regulation under fast load transients
Temp. Coefficient	±13 ppm/°C (max); guarantees < ±0.3 mV drift over full −40 °C to +125 °C automotive range
Voltage Deviation	±3 mV over −40 °C to +125 °C; defines worst-case output error in closed-loop feedback systems
Reference Input Current	1.5–3 µA (max at temp extremes); minimizes divider resistor power loss and thermal drift

Pinout & Package

TL1431ACZ uses the TO-92 plastic package (bulk or ammopack), with 3 leads and a thermal resistance of R_thJA = 200 °C/W. The package is lead-free, RoHS-compliant, and rated for automotive applications per AEC-Q100.

Pin/Terminal	Circuit Role	Design Meaning
Anode (Pin 1)	Current return path	Connected to system ground or low-side reference point; carries full cathode current minus reference current
Cathode (Pin 2)	Regulated output node	Sinks current to maintain voltage at REF pin; directly interfaces with optocoupler anode or error amp input
REF (Pin 3)	Feedback input	High-impedance (≤3 µA) input sensing divided-down output voltage; sets regulation point via external R1/R2 network

Key Features

Feature	Design Value
Adjustable output voltage	2.5 V to 36 V via two external resistors - eliminates need for multiple fixed-reference SKUs
Automotive temperature range	−40 °C to +125 °C operation - qualified per AEC-Q100 for engine control, body electronics, and ADAS power rails
Low dynamic impedance	0.22 Ω typical - maintains tight regulation during rapid load steps in SMPS feedback paths
High initial accuracy	0.25% reference voltage tolerance - reduces calibration overhead in precision power supplies
Wide cathode current range	1–100 mA sink capability - supports direct drive of PC817/PC817x optocouplers without series resistors

Applications

Isolated Flyback Converter Feedback

Programmable Lab Power Supply

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

IC Role / Device Role / Timing Role: Shunt reference providing precise voltage sampling at secondary side; drives optocoupler LED to close primary-side control loop.

Use Value: Enables ±1% output regulation across line/load/temperature with minimal external components and no secondary-side LDO.

Use Scenario: Serves as adjustable reference in digitally controlled bench power supplies with 0–30 V output range.

IC Role / Device Role / Timing Role: Precision voltage setpoint generator interfaced to DAC output or potentiometer divider.

Use Value: Delivers 0.25% initial accuracy and < ±3 mV drift over 0–70 °C, enabling sub-10 mV output resolution.

Automotive Battery Monitor

Industrial 4–20 mA Transmitter

Use Scenario: Monitors 12 V vehicle battery voltage with over/under-voltage detection thresholds.

IC Role / Device Role / Timing Role: Stable reference for comparator inputs in battery protection circuitry; operates continuously at −40 °C to +125 °C.

Use Value: Maintains ±0.25% reference stability across full automotive temperature range, eliminating recalibration needs.

Use Scenario: Sets reference for V/I conversion stage in 4–20 mA loop-powered sensors.

IC Role / Device Role / Timing Role: Low-drift, low-current reference driving op-amp input in current-output stage.

Use Value: 1.5–3 µA reference current minimizes loading on high-impedance sensor outputs and improves long-term accuracy.

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 pinout and electrical specs; TI-manufactured part with ±0.5% initial tolerance (vs. ST's ±0.25%)	Not qualified to AEC-Q100; limited to commercial/industrial temp range (−40 °C to +85 °C)	Select when cost sensitivity outweighs automotive qualification and tighter initial accuracy
LM4040CIM3-ADJ	Series reference (not shunt); requires external pass transistor; 0.5% initial accuracy; 100 µA max quiescent current	Higher component count; unsuitable for direct optocoupler drive due to sourcing-only architecture	Select only for ultra-low-power applications where shunt topology is not required

Compared with TL431ACZ and LM4040CIM3-ADJ, TL1431ACZ uniquely combines AEC-Q100 qualification, 0.25% initial accuracy, and direct 1–100 mA sink capability in TO-92 - making it optimal for automotive and isolated feedback designs where space, reliability, and precision are jointly constrained.

Availability

TL1431ACZ is available at Aetrix Electronics and suitable for automotive battery monitors, isolated flyback converters, programmable lab power supplies, and industrial 4–20 mA transmitters requiring stable component supply across extended temperature ranges.

Supply support for TL1431ACZ 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, analog chips, and MEMS sensors for automotive, industrial, and consumer markets.

The TL1431 belongs to ST's precision analog reference product line, engineered specifically for high-reliability feedback control in automotive power systems and isolated switching regulators.

FAQ

What is the maximum cathode-to-anode voltage for TL1431ACZ?

The absolute maximum cathode-to-anode voltage (V_KA) is 37 V. Operation above this rating risks permanent damage. For reliable long-term use, the recommended maximum operating V_KA is 36 V - matching the upper limit of its adjustable output range and ensuring margin against transients in automotive and industrial environments.

Can TL1431ACZ replace TL431 in existing designs?

Yes - TL1431ACZ is pin-compatible and functionally equivalent to TL431ACZ in TO-92 packages, with identical pinout (Anode/Cathode/REF) and nearly identical electrical behavior. However, TL1431ACZ offers tighter 0.25% initial accuracy and AEC-Q100 qualification, making it a drop-in upgrade for automotive and high-precision applications.

What is the minimum cathode current required for regulation?

The minimum cathode current (I_min) is 0.5 mA at 25 °C and rises to 0.6 mA at +125 °C. Below this threshold, regulation degrades and output voltage deviates from the setpoint. Designers must ensure external circuitry (e.g., optocoupler LED + series resistor) draws ≥0.6 mA under worst-case conditions to guarantee stable operation.

How does TL1431ACZ handle capacitive loads on the cathode?

TL1431ACZ remains stable with up to 10 nF capacitive load at the cathode when V_KA = 5 V, but stability margin decreases at higher voltages (e.g., ≤1 nF at V_KA = 36 V). For larger capacitors, a series resistor (typically 1–10 Ω) between cathode and capacitor is recommended to dampen potential oscillation - verified in Figure 20 of the datasheet.

TL1431ACZ 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:: ±0.25%

Temperature Coefficient:: 90ppm/°C

Noise - 0.1Hz to 10Hz:: -

Noise - 10Hz to 10kHz:: -

Voltage - Input:: -

Current - Supply:: -

Current - Cathode:: 600 µA

Operating Temperature:: -20°C ~ 70°C (TA)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-92-3

TL1431ACZ FAQ

1.How can I place an order for TL1431ACZ through Aetrix?

Please submit a Request for Quotation (RFQ) for TL1431ACZ 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 TL1431ACZ reliable?

The price and inventory of TL1431ACZ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for TL1431ACZ is usually 5 days.

3.What payment methods are accepted for TL1431ACZ?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for TL1431ACZ transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for TL1431ACZ?

TL1431ACZ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your TL1431ACZ 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 TL1431ACZ?

For technical support, including TL1431ACZ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your TL1431ACZ requirements.

6.How does Aetrix verify that TL1431ACZ is sourced from the original manufacturer or authorized distributors?

All TL1431ACZ 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 TL1431ACZ meets industry standards.

7.What is the process for return or replacement of TL1431ACZ?

All TL1431ACZ units undergo pre-shipment inspection (PSI). If there is an issue with TL1431ACZ, 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 TL1431ACZ part is unused and in its original packaging.

Return procedure for TL1431ACZ:

1.Submit a request within 90 days.

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

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