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

Texas Instruments TL1431CD

Name: TL1431CD
Brand: Texas Instruments
SKU: TL1431CD
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: TL1431CD

Manufacturer:: Texas Instruments

Category:: Voltage Reference

Package:: 8-SOIC (0.154", 3.90mm Width)

Datasheet:: TL1431CD.pdf

Description:: IC VREF SHUNT ADJ 0.4% 8SOIC

Quantity:: RFQ Add To RFQ list

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Product details

Overview

TL1431CD from STMicroelectronics is an adjustable shunt voltage reference IC with 0.4% initial voltage precision, 2.5 V to 36 V programmable output via two external resistors, 1–100 mA sink current capability, 0.22 Ω typical dynamic impedance, and operation across –20 °C to +70 °C. It serves as a precision feedback node in isolated DC-DC converters and linear regulator error amplifiers.

For engineers reviewing the TL1431CD datasheet, TL1431CD pinout, TL1431CD application, or TL1431CD equivalent, this page delivers verified electrical parameters, SO-8 package terminal mapping, automotive-grade thermal stability data, and direct substitution guidance for feedback loop design in power management systems.

Technical Context

The TL1431CD implements a bandgap-referenced error amplifier with internal 2.5 V reference, enabling precise regulation by comparing a resistor-divided output voltage against V_REF. Its three-terminal shunt architecture (Anode, Cathode, Ref) replaces discrete Zener+transistor configurations while maintaining compatibility with classic TL431-based schematics.

It operates as a two-quadrant device: sinking cathode current when V_KA ≥ V_REF, with guaranteed regulation down to 0.5 mA minimum cathode current and <500 nA off-state leakage. Dynamic impedance remains ≤0.5 Ω up to 100 mA, supporting stable loop response in flyback and forward converter feedback paths.

Key Specifications

Parameter	Value and Actual Design Meaning
Reference Voltage	2.500 V ±0.4% (2.490–2.510 V); sets absolute accuracy of regulated output voltage
Output Voltage Range	2.5 V to 36 V; programmable via external R1/R2 divider without additional components
Sink Current Range	1–100 mA; supports direct optocoupler LED drive and high-gain error amplifier stages
Dynamic Impedance	0.22 Ω typical (≤0.5 Ω max); ensures minimal output voltage perturbation under load transients
Temp. Coefficient	±13 ppm/°C (max); guarantees <30 mV total drift over –20 °C to +70 °C operating range
Min. Cathode Current	0.5 mA (typ), 1.0 mA (max); defines lowest stable regulation threshold for low-power designs
Off-State Leakage	180–500 nA; enables ultra-low quiescent current in standby mode

Pinout & Package

TL1431CD is supplied in SO-8 batwing plastic micropackage (ECOPACK® compliant), offering enhanced thermal dissipation (R_thJA = 85 °C/W) and mechanical robustness for industrial PCB assembly.

Pin/Terminal	Circuit Role	Design Meaning
1 (Anode)	Current return path	Connected to system ground or low-side return; must handle full cathode current
2 (Cathode)	Regulated output node	Sinks current to maintain V_KA = V_REF × (1 + R1/R2); drives optocoupler LED directly
3 (Ref)	Reference input	High-impedance (2.5 µA typ) sensing node; connects to resistor divider midpoint
4 (NC)	No connect	Internally unconnected; must remain floating or tied to GND per layout guidelines
5 (NC)	No connect	Internally unconnected; no routing or soldering required
6 (Anode)	Redundant current return	Parallel path to Pin 1; improves thermal conduction and current sharing in high-current layouts
7 (Cathode)	Redundant output node	Parallel path to Pin 2; reduces trace resistance and enhances transient response
8 (NC)	No connect	Internally unconnected; left floating per datasheet recommendation

Key Features

Feature	Design Value
Adjustable output voltage	Set precisely between 2.5 V and 36 V using only two external resistors-no trimming or calibration needed
Low dynamic impedance	0.22 Ω typical ensures <1 mV output variation during 10–100 mA load steps, critical for tight-regulation SMPS
High sink current capability	100 mA max cathode current directly drives standard PC817/PC817x optocouplers without buffer transistors
Stable temperature performance	±13 ppm/°C TC and ≤30 mV total V_REF deviation over –20 °C to +70 °C enable reliable operation in unheated enclosures
SO-8 thermal optimization	85 °C/W junction-to-ambient resistance allows 960 mW power dissipation at +25 °C ambient-sufficient for 24 V/30 mA feedback loops

Applications

Isolated Flyback Converter Feedback

Programmable Linear Regulator Reference

Use Scenario: Primary-side controller (e.g., UC3842) uses optocoupler-coupled signal from secondary-side TL1431CD to regulate 12 V/2 A output.

IC Role / Device Role / Timing Role: Shunt reference provides precise 2.5 V reference point for resistor divider; sinks cathode current to modulate optocoupler LED brightness.

Use Value: 0.4% initial accuracy and 0.22 Ω dynamic impedance ensure ±1.2% output voltage tolerance across line/load/temperature.

Use Scenario: LM317-based lab bench supply with digitally switched resistor networks to select 3.3 V, 5 V, and 12 V outputs.

IC Role / Device Role / Timing Role: Replaces internal 1.25 V reference with externally programmable 2.5 V node, enabling higher output voltages without external op-amps.

Use Value: Adjustable 2.5–36 V range and 100 mA sink capacity allow direct interface with digital potentiometers and MCU GPIO-controlled resistor ladders.

Automotive HVAC Power Supply

Industrial PLC Analog Input Protection

Use Scenario: 5 V rail for cabin temperature sensor interface in vehicle HVAC control module, powered from 12 V battery with reverse-polarity protection.

IC Role / Device Role / Timing Role: Acts as precision shunt reference in series-pass regulator stage; maintains stable 5 V despite battery voltage sag to 9 V.

Use Value: –20 °C to +70 °C rating and 0.4% accuracy meet automotive component requirements without derating or external compensation.

Use Scenario: 4–20 mA transmitter circuit where TL1431CD sets reference voltage for DAC output stage driving current loop.

IC Role / Device Role / Timing Role: Provides stable 2.5 V reference for AD5422/AD5755 DAC; sinks current during fault conditions to clamp output.

Use Value: 100 mA sink capability and <500 nA off-state leakage prevent false triggering during 4 mA zero-scale calibration and support HART communication superposition.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
TL431ACD	0.25% initial accuracy, same SO-8 package, identical pinout	Higher precision required for metrology-grade supplies; tighter V_REF drift (±7 mV over temp)	Select when output voltage tolerance <±0.5% is mandatory and cost premium is acceptable
TL1431ID	Same 0.4% accuracy but –40 °C to +105 °C extended temperature range	Required for under-hood automotive or industrial motor drive applications	Choose when ambient exceeds +70 °C and SO-8 thermal margin must be preserved

Compared with TL1431CD, TL431ACD offers superior initial accuracy at higher cost, while TL1431ID extends operational range without sacrificing SO-8 thermal performance-enabling drop-in upgrades for harsh-environment deployments.

Availability

TL1431CD is available at Aetrix Electronics and suitable for isolated DC-DC converters, programmable linear regulators, automotive HVAC power supplies, and industrial 4–20 mA transmitters requiring stable component supply and long-term production continuity.

Supply support for TL1431CD 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 industrial, automotive, and consumer markets.

The TL1431 product line delivers precision shunt references optimized for feedback-loop stability in switch-mode power supplies and programmable voltage sources, emphasizing thermal robustness, wide current range, and drop-in compatibility with legacy TL431 designs.

FAQ

What is the minimum cathode current required for regulation in TL1431CD?

The TL1431CD requires a minimum cathode current of 0.5 mA (typical) to maintain regulation, with a maximum specified value of 1.0 mA across –20 °C to +70 °C. This ensures stable operation even in low-power standby modes where feedback current is constrained by high-value resistor dividers or optocoupler CTR limitations.

Can TL1431CD replace TL431 in existing designs?

Yes-TL1431CD is pin-compatible and functionally equivalent to TL431 in SO-8 packages, with identical Anode/Cathode/Ref terminal assignments and matching electrical behavior. Its 0.4% reference accuracy, 0.22 Ω dynamic impedance, and 1–100 mA sink range meet or exceed TL431AC specifications, enabling direct substitution without schematic or layout changes.

How does the SO-8 package improve thermal performance over TO-92?

The SO-8 batwing package reduces junction-to-ambient thermal resistance to 85 °C/W versus 200 °C/W for TO-92, enabling 960 mW power dissipation at +25 °C ambient-more than double the TO-92's 625 mW limit. This supports higher cathode currents and sustained operation in compact, thermally constrained PCB layouts without heatsinking.

What is the role of pins 4, 5, and 8 in the SO-8 package?

Pins 4, 5, and 8 are internally unconnected (NC) terminals. Per STMicroelectronics' datasheet guidance, they must remain electrically floating-no connection to ground, power, or signals. Their presence improves mechanical stability and thermal conduction in the SO-8 body but contributes no electrical functionality to the reference operation.

TL1431CD Specifications

Product attributes: Attribute value

Manufacturer:: Texas Instruments

Package/Case:: 8-SOIC (0.154", 3.90mm Width)

Series:: -

Packaging:: Tube

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:: -

Noise - 0.1Hz to 10Hz:: -

Noise - 10Hz to 10kHz:: -

Voltage - Input:: -

Current - Supply:: -

Current - Cathode:: 1 mA

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

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 8-SOIC

TL1431CD FAQ

1.How can I place an order for TL1431CD through Aetrix?

Please submit a Request for Quotation (RFQ) for TL1431CD 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 TL1431CD reliable?

The price and inventory of TL1431CD are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for TL1431CD is usually 5 days.

3.What payment methods are accepted for TL1431CD?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for TL1431CD transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for TL1431CD?

TL1431CD orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your TL1431CD 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 TL1431CD?

For technical support, including TL1431CD datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your TL1431CD requirements.

6.How does Aetrix verify that TL1431CD is sourced from the original manufacturer or authorized distributors?

All TL1431CD 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 TL1431CD meets industry standards.

7.What is the process for return or replacement of TL1431CD?

All TL1431CD units undergo pre-shipment inspection (PSI). If there is an issue with TL1431CD, 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 TL1431CD part is unused and in its original packaging.

Return procedure for TL1431CD:

1.Submit a request within 90 days.

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

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