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

STMicroelectronics TL431ACL3T

Name: TL431ACL3T
Brand: STMicroelectronics
SKU: TL431ACL3T
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: TL431ACL3T

Manufacturer:: STMicroelectronics

Category:: Voltage Reference

Package:: TO-236-3, SC-59, SOT-23-3

Datasheet:: TL431ACL3T.pdf

Description:: IC VREF SHUNT ADJ 1% SOT23-3

Quantity:: RFQ Add To RFQ list

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Inventory:3,105

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Product details

Overview

TL431ACL3T from STMicroelectronics is an AEC-Q100 qualified automotive-grade adjustable shunt voltage reference in SOT23-3 package, delivering 1% initial voltage precision (2.5 V nominal), −40 °C to +125 °C operating range, 0.22 Ω typical dynamic impedance, and 1–100 mA sink current capability. It serves as a precision feedback element in isolated DC-DC converters and battery management systems requiring stable regulation under harsh thermal conditions.

For engineers reviewing the TL431ACL3T datasheet, TL431ACL3T pinout, TL431ACL3T application, or TL431ACL3T equivalent, key selection considerations include its 1% reference accuracy at automotive temperature extremes, SOT23-3 footprint compatibility with space-constrained power rails, cathode-anode voltage headroom up to 36 V, and guaranteed dynamic impedance below 0.5 Ω across full load range.

Technical Context

The TL431ACL3T implements a bandgap-based precision reference core with internal error amplifier and NPN output stage, configured as a 3-terminal shunt regulator. Its reference input (REF) compares against an internal 2.453–2.537 V threshold, controlling cathode current to maintain setpoint voltage across external resistor dividers.

It operates in closed-loop feedback mode where cathode-to-anode voltage (V_KA) is regulated via external resistive programming between REF and ANODE, enabling adjustable output from 2.5 V to 36 V. Thermal stability is ensured by curvature-compensated bandgap design validated over −40 °C to +125 °C with ≤30 mV total ∆V_ref deviation.

Key Specifications

Parameter	Value and Actual Design Meaning
Reference Voltage	2.453–2.537 V at 25 °C; enables precise 2.5 V–36 V programmable output with two external resistors
Voltage Accuracy	±1% over full −40 °C to +125 °C range; meets automotive functional safety requirements for feedback path stability
Sink Current Range	1–100 mA; supports direct drive of optocoupler LEDs or error amplifier inputs without external buffering
Dynamic Impedance	0.22 Ω typical (≤0.5 Ω max); ensures minimal output voltage perturbation during transient load steps
Cathode-Anode Voltage	Up to 36 V; allows use in 24 V and 48 V automotive bus applications with sufficient headroom
Reference Input Current	≤4 µA typical at 25 °C; reduces divider network power loss and improves high-impedance sensing accuracy
Thermal Resistance	R_thJA = 248 °C/W (SOT23-3); defines maximum power dissipation limit of ~250 mW at 125 °C ambient

Pinout & Package

SOT23-3 plastic surface-mount package with gull-wing leads, 1.9 mm × 2.9 mm footprint, 1.12 mm height, and ECOPACK® RoHS-compliant finish.

Pin/Terminal	Circuit Role	Design Meaning
Pin 1 (Cathode)	Output current sink terminal	Connects to regulated rail or optocoupler anode; carries full load current up to 100 mA
Pin 2 (Anode)	Current return path	Connected to system ground or low-side reference point; completes shunt regulation loop
Pin 3 (Ref)	Precision reference input	High-impedance node comparing external divider voltage to internal 2.45–2.54 V bandgap; sets output voltage

Key Features

Feature	Design Value
AEC-Q100 qualification	Validated for automotive Grade 1 (−40 °C to +125 °C), including HTOL, TC, ESD-HBM 2 kV, and board-level reliability testing
Adjustable output range	2.5 V to 36 V via two-resistor divider; eliminates need for multiple fixed-voltage references in multi-rail designs
Low dynamic impedance	0.22 Ω typical ensures <10 mV output shift under 10 mA load transients-critical for tight-tolerance SMPS feedback
Wide operating current	Stable regulation from 1 mA minimum cathode current; supports ultra-low-power standby modes without dropout
Temperature-stable reference	≤30 mV total ∆V_ref over −40 °C to +125 °C; maintains ±0.6% output accuracy in engine bay environments

Applications

Automotive DC-DC Converters

Industrial Power Supplies

Use Scenario: Feedback control in 12 V/48 V bidirectional buck-boost converters for 48 V mild-hybrid vehicles.

IC Role / Device Role / Timing Role: Shunt reference providing precision voltage setpoint to PWM controller error amplifier.

Use Value: 1% accuracy and −40 °C to +125 °C operation ensure consistent regulation despite under-hood thermal cycling and voltage transients.

Use Scenario: Output voltage trimming and overvoltage protection in programmable bench power supplies.

IC Role / Device Role / Timing Role: Adjustable reference source for DAC-controlled feedback loop with manual potentiometer override.

Use Value: 0.22 Ω dynamic impedance minimizes output ripple during rapid load changes, improving transient response fidelity.

Battery Management Systems

Isolated Flyback Controllers

Use Scenario: Cell voltage monitoring and charge termination reference in 12S Li-ion battery packs.

IC Role / Device Role / Timing Role: Precision voltage comparator input reference for analog front-end ADC scaling and fault detection thresholds.

Use Value: ≤4 µA reference input current reduces parasitic loading on high-impedance cell tap resistors, preserving measurement accuracy.

Use Scenario: Secondary-side feedback in isolated flyback converters using optocoupler-coupled regulation.

IC Role / Device Role / Timing Role: Cathode-driven optocoupler LED biasing to transmit isolated error signal to primary-side controller.

Use Value: 100 mA sink capability enables direct optocoupler drive without series transistor, reducing BOM count and layout area.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
TL431CL3T	2% initial accuracy (vs. 1%), same SOT23-3 package and −40 °C to +125 °C rating	Acceptable where cost sensitivity outweighs tight regulation tolerance; higher ∆V_ref drift may impact long-term calibration stability	Select when budget constraints dominate and system-level calibration compensates for wider initial tolerance.
TL431BIL3T	0.5% initial accuracy, same automotive temp range and SOT23-3 package	Required for ASIL-B functional safety paths where tighter reference uncertainty is mandated for fault detection coverage	Choose for safety-critical automotive subsystems needing enhanced reference precision without changing PCB layout.

Compared with TL431CL3T, TL431ACL3T offers tighter initial tolerance for improved open-loop accuracy; compared with TL431BIL3T, it trades 0.5% precision for lower unit cost while retaining full automotive qualification and thermal performance.

Availability

TL431ACL3T is available at Aetrix Electronics and suitable for automotive power conversion, industrial SMPS design, and battery management systems requiring stable component supply with AEC-Q100 compliance and extended temperature support.

Supply support for TL431ACL3T 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-loop stability in regulated power supplies, with variants engineered specifically for automotive-grade reliability and wide-temperature operation.

FAQ

What is the minimum cathode current required for regulation in TL431ACL3T?

The TL431ACL3T requires a minimum cathode current of 0.5 mA to maintain regulation, verified across −40 °C to +125 °C. This value is specified in Table 3 of the datasheet under "Imin Minimum cathode current for regulation" and remains stable over temperature, enabling reliable startup and light-load operation in energy-efficient designs.

Can TL431ACL3T replace TL431ACD in SO-8 packages without circuit modification?

No-TL431ACL3T uses SOT23-3 pinout (Cathode-Anode-Ref), while TL431ACD uses SO-8 (Cathode-NC-Ref-NC-NC-Anode-NC-NC). Direct replacement requires PCB redesign due to incompatible pin mapping, package size, and thermal characteristics; SO-8 offers lower R_thJA (85 °C/W vs. 248 °C/W), affecting power handling.

How does the 1% accuracy of TL431ACL3T compare to the TL431B series?

TL431ACL3T guarantees ±1% initial reference voltage accuracy, whereas TL431BIL3T achieves ±0.5%. Both share identical temperature range and package, but the B-grade version undergoes tighter binning and additional characterization-making it suitable for ASIL-B applications where reference uncertainty directly impacts fault detection thresholds.

Is TL431ACL3T compatible with capacitive loads on the cathode node?

Yes-ST's datasheet Figure 21 confirms stable operation with up to 10 µF capacitive loads on the cathode, provided the external resistor divider maintains ≥10 kΩ Thevenin impedance. This supports direct connection to low-ESR ceramic output capacitors in compact DC-DC modules without added phase compensation.

TL431ACL3T Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Package/Case:: TO-236-3, SC-59, SOT-23-3

Series:: -

Packaging:: Tape & Reel (TR)

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:: 600 µA

Operating Temperature:: 0°C ~ 70°C (TA)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-23-3

TL431ACL3T FAQ

1.How can I place an order for TL431ACL3T through Aetrix?

Please submit a Request for Quotation (RFQ) for TL431ACL3T 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 TL431ACL3T reliable?

The price and inventory of TL431ACL3T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for TL431ACL3T is usually 5 days.

3.What payment methods are accepted for TL431ACL3T?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for TL431ACL3T transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for TL431ACL3T?

TL431ACL3T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your TL431ACL3T 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 TL431ACL3T?

For technical support, including TL431ACL3T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your TL431ACL3T requirements.

6.How does Aetrix verify that TL431ACL3T is sourced from the original manufacturer or authorized distributors?

All TL431ACL3T 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 TL431ACL3T meets industry standards.

7.What is the process for return or replacement of TL431ACL3T?

All TL431ACL3T units undergo pre-shipment inspection (PSI). If there is an issue with TL431ACL3T, 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 TL431ACL3T part is unused and in its original packaging.

Return procedure for TL431ACL3T:

1.Submit a request within 90 days.

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

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