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STMicroelectronics TL431ICT
- Part No.:
- TL431ICT
- Manufacturer:
- STMicroelectronics
- Category:
- Voltage Reference
- Package:
- 6-TSSOP, SC-88, SOT-363
- Datasheet:
-
TL431ICT.pdf
- Description:
- IC VREF SHNT ADJ 2.21% SOT323-6L
- Quantity:
- Payment:
- Shipping:
Inventory:7,963
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Product details
Overview
TL431ICT from STMicroelectronics is an AEC-Q100 qualified automotive-grade adjustable shunt voltage reference in SOT323-6 package, delivering 2.5–36 V output via two external resistors, ±2% initial voltage accuracy, 0.22 Ω typical dynamic impedance, and operation across –40 °C to +125 °C for engine control unit (ECU) feedback regulation.
For engineers reviewing the TL431ICT datasheet, TL431ICT pinout, TL431ICT application, or TL431ICT equivalent, this page provides verified pin functions, automotive temperature-stable performance data, shunt regulator design meaning of dynamic impedance and reference current, and validated alternative options for precision feedback loops in power converters and battery management systems.
Technical Context
The TL431ICT implements a three-terminal adjustable shunt regulator with internal bandgap reference, error amplifier, and NPN output stage. It operates as a programmable Zener replacement, sinking cathode current (1–100 mA) proportional to deviation between sensed reference voltage and internal 2.5 V threshold.
Its architecture enables stable closed-loop regulation without external compensation in most applications, supported by 0.22 Ω dynamic impedance and <1.8 µA reference input current. The SOT323-6 package supports high-density automotive PCB layouts while maintaining thermal resistance of 221 °C/W (junction-to-ambient).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage Range | 2.5 V to 36 V - set externally with two resistors; enables flexible feedback scaling for DC-DC converters and LDOs. |
| Initial Voltage Accuracy | ±2% at 25 °C - defines maximum deviation in reference threshold before trimming; impacts system-level output tolerance. |
| Temperature Range | –40 °C to +125 °C - qualified per AEC-Q100 Grade 1; ensures stable regulation in under-hood automotive environments. |
| Dynamic Impedance | 0.22 Ω typical - determines output voltage ripple rejection; lower value improves load/transient regulation fidelity. |
| Cathode Current Range | 1 mA to 100 mA - defines minimum startup current and maximum sink capability; sets usable range for error amplifier drive. |
| Reference Input Current | ≤1.8 µA max - limits resistor divider loading; enables high-impedance programming for low-power bias networks. |
| Thermal Resistance | 221 °C/W (Junction-to-Ambient) - constrains power dissipation in SOT323-6; requires derating above 70 °C ambient. |
Pinout & Package
SOT323-6 plastic surface-mount package (3.0 × 1.7 × 0.9 mm), ECOPACK® compliant, with exposed pad for thermal enhancement and mechanical stability on automotive PCBs.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 (Cathode) | Current Sink Output | Primary output node; connects to converter feedback node or optocoupler anode; must handle full regulated current. |
| Pin 2 (Anode) | Current Return Path | Low-side return for cathode current; ties to ground or negative rail; forms shunt path with cathode. |
| Pin 3 (Ref) | Reference Input | Senses divided output voltage; internal comparator compares to 2.5 V bandgap; high-impedance (≤1.8 µA). |
| Pin 4 (NC) | No Connect | Internally unconnected; must remain floating or grounded per layout guidelines to avoid parasitic coupling. |
| Pin 5 (NC) | No Connect | Internally unconnected; no electrical function; recommended to leave unconnected or tie to ground for EMI control. |
| Pin 6 (NC) | No Connect | Internally unconnected; unused terminal; no routing required; may be used as thermal pad anchor if soldered. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q100 qualification | Grade 1 (–40 °C to +125 °C); includes stress testing for automotive reliability-enables use in safety-critical ECU power rails. |
| Adjustable 2.5–36 V output | Programmed with two external resistors only; eliminates need for multiple fixed-voltage references in BOM. |
| 0.22 Ω dynamic impedance | Ensures <1 mV output shift per 100 mA load change; critical for tight-regulation isolated flyback feedback loops. |
| 1–100 mA cathode current range | Supports direct optocoupler drive (e.g., PC817) without buffer transistor; simplifies isolated SMPS designs. |
| ≤1.8 µA reference input current | Permits >1 MΩ feedback dividers; reduces power loss and thermal drift in high-impedance sensing networks. |
Applications
| Automotive Engine Control Unit (ECU) | Industrial Isolated DC-DC Converter |
|---|---|
|
Use Scenario: Regulating 5 V microcontroller supply in engine bay under wide temperature and vibration conditions. IC Role / Device Role / Timing Role: Shunt voltage reference in feedback loop of buck converter; sets output voltage via resistor divider tied to TL431ICT Ref pin. Use Value: ±2% accuracy and –40 °C to +125 °C operation ensure consistent MCU reset behavior and ADC reference stability despite thermal cycling. |
Use Scenario: Secondary-side voltage sensing in 24 V input/12 V output flyback converter powering PLC I/O modules. IC Role / Device Role / Timing Role: Adjustable shunt reference driving optocoupler LED; closes isolation barrier feedback loop with <0.22 Ω impedance. Use Value: Low dynamic impedance minimizes output voltage deviation during load transients, improving regulation within ±1.5% over 10–100% load. |
| Battery Management System (BMS) Cell Monitor | Medical Power Supply Feedback |
|
Use Scenario: Precision voltage reference for cell voltage measurement circuitry in 12S Li-ion pack monitor. IC Role / Device Role / Timing Role: Stable 2.5 V reference source for ADC input scaling; powered from isolated auxiliary rail. Use Value: ≤1.8 µA reference current avoids loading high-resistance voltage dividers, preserving measurement accuracy below ±1 LSB error. |
Use Scenario: Feedback reference in Class I medical AC-DC adapter requiring low leakage and long-term stability. IC Role / Device Role / Timing Role: Programmable shunt regulator setting 12 V output; integrated into transformerless feedback network. Use Value: AEC-Q100 qualification correlates with high-reliability process control, supporting 10-year MTBF requirements in life-critical equipment. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar adjustable shunt reference applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TL431ACCT | ±1% initial accuracy, same SOT323-6 package, identical temp range (–40 °C to +125 °C) | Higher precision required in medical sensor signal chains where 1% tolerance directly impacts calibration validity | Select when tighter initial voltage tolerance is mandatory and cost premium is acceptable for calibration-critical stages |
| TL432IL3T | SOT23-3 package, same ±2% accuracy, adds internal 2.5 V reference bypass capacitor (reduces external component count) | Preferred in space-constrained portable diagnostics devices where board area savings outweigh thermal resistance penalty (248 °C/W vs. 221 °C/W) | Choose for ultra-compact layouts where reduced footprint justifies higher thermal resistance and absence of NC pins for EMI shielding |
Compared with TL431ICT, TL431ACCT offers improved initial accuracy at equal thermal performance, while TL432IL3T trades package size and integrated capacitance for higher junction-to-ambient resistance-making TL431ICT optimal for thermally demanding, cost-sensitive automotive feedback where ±2% is sufficient.
Availability
TL431ICT is available at Aetrix Electronics and suitable for automotive engine control units, industrial isolated DC-DC converters, and battery management systems requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for TL431ICT 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, microcontroller, power, and automotive ICs for industrial and transportation markets.
The TL431 series belongs to ST's precision analog voltage reference product line, engineered specifically for automotive-grade feedback regulation, offering AEC-Q100 compliance, wide operating temperature, and robust dynamic impedance performance.
FAQ
What is the maximum cathode-to-anode voltage rating for TL431ICT?
The absolute maximum cathode-to-anode voltage (VKA) is 37 V. Operation beyond this risks permanent damage. In practice, the device regulates up to 36 V output, so design margin must keep VKA ≤37 V under all transient and fault conditions-including input surges and load-dump events in automotive systems.
Can TL431ICT replace TL431CZ in a TO-92 design?
No-TL431ICT uses SOT323-6 packaging and has different thermal characteristics (221 °C/W J-A vs. 200 °C/W for TO-92), pinout (6-pin vs. 3-pin), and NC terminals. Direct replacement requires PCB redesign, thermal validation, and verification of reference current path integrity due to differing internal routing and parasitic capacitance.
Does TL431ICT require an external capacitor on the Ref pin?
No external capacitor is required on the Ref pin for stability. The device is internally compensated and remains stable with purely resistive feedback dividers. However, a 1 nF ceramic capacitor may be added in noisy environments to suppress RF pickup-this does not affect regulation but improves noise immunity without altering DC accuracy.
How does the 0.22 Ω dynamic impedance impact load regulation?
A 0.22 Ω dynamic impedance means a 100 mA change in cathode current causes only ~22 mV output shift (ΔV = Z × ΔI). This directly determines load regulation error: e.g., in a 12 V output design with 0–1 A load swing, TL431ICT contributes <0.2% voltage deviation-critical for meeting tight regulation specs in automotive and medical power supplies.
TL431ICT Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Package/Case:
- 6-TSSOP, SC-88, SOT-363
- 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:
- ±2.21%
- Temperature Coefficient:
- -
- 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:
- Surface Mount
- Supplier Device Package:
- SOT-323-6L
TL431ICT FAQ
1.How can I place an order for TL431ICT through Aetrix?
Please submit a Request for Quotation (RFQ) for TL431ICT 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 TL431ICT reliable?
The price and inventory of TL431ICT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for TL431ICT is usually 5 days.
3.What payment methods are accepted for TL431ICT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for TL431ICT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for TL431ICT?
TL431ICT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your TL431ICT 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 TL431ICT?
For technical support, including TL431ICT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your TL431ICT requirements.
6.How does Aetrix verify that TL431ICT is sourced from the original manufacturer or authorized distributors?
All TL431ICT 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 TL431ICT meets industry standards.
7.What is the process for return or replacement of TL431ICT?
All TL431ICT units undergo pre-shipment inspection (PSI). If there is an issue with TL431ICT, 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 TL431ICT part is unused and in its original packaging.
Return procedure for TL431ICT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
TL431ICT Tags
-
TL431AIDBZR
Texas Instruments
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TL431BQDBZR
Texas Instruments
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AN431AN-ATRG1
Diodes Incorporated
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LM4040CYM3-2.5-TR
Microchip Technology
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LM4040CYM3-4.1-TR
Microchip Technology
-
LM4040EIM3-2.5/NOPB
Texas Instruments
-
AZ431LBNTR-G1
Diodes Incorporated
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LM4040D20IDBZR
Texas Instruments
-
LM4041DIM3-ADJ/NOPB
Texas Instruments
-
LM4040DIM3X-2.5/NOPB
Texas Instruments
-
LM4040DIM3-2.5/NOPB
Texas Instruments
-
AZ431LANTR-G1
Diodes Incorporated
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