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STMicroelectronics TL431IZT
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- Part No.:
- TL431IZT
- Manufacturer:
- STMicroelectronics
- Category:
- Voltage Reference
- Package:
- TO-226-2, TO-92-2 (TO-226AC)
- Datasheet:
-
TL431IZT.pdf
- Description:
- IC VREF SHUNT ADJ 2.21% TO92-3
- Quantity:
- Payment:
- Shipping:
Inventory:8,350
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Product details
Overview
TL431IZT from STMicroelectronics is an AEC-Q100 qualified automotive-grade adjustable shunt voltage reference with 2% initial voltage accuracy, operating across –40 °C to +125 °C, supporting 2.5–36 V programmable output via two external resistors, delivering 1–100 mA sink current, and featuring 0.22 Ω typical dynamic impedance for precision feedback in isolated DC-DC converters.
For engineers reviewing the TL431IZT datasheet, TL431IZT pinout, TL431IZT application, or TL431IZT equivalent, this page delivers verified package mapping (TO-92), confirmed thermal resistance (200 °C/W junction-to-ambient), exact cathode-anode voltage rating (37 V), and validated automotive temperature stability data - all critical for power supply safety margining and functional safety compliance.
Technical Context
The TL431IZT implements a precision 2.5 V internal bandgap reference with high-gain error amplifier and NPN output stage, enabling accurate voltage regulation through external resistor divider feedback. Its operation requires minimum 0.5 mA cathode current to maintain regulation and exhibits <30 mV total reference voltage deviation over –40 °C to +125 °C.
It functions as a 3-terminal shunt regulator where the REF pin senses divided output voltage, the CATHODE sinks load current, and the ANODE connects to ground or return path. Dynamic impedance remains ≤0.5 Ω up to 100 mA, ensuring stable loop response in flyback and forward converter feedback networks.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reference Voltage | 2.5 V nominal, ±2% tolerance at 25 °C - sets absolute accuracy of regulated output voltage |
| Output Voltage Range | 2.5 to 36 V programmable - enables single device coverage across 12 V, 24 V, and 48 V automotive rail designs |
| Sink Current Capability | 1 to 100 mA - supports direct drive of optocoupler LEDs or secondary-side error amplifiers without buffering |
| Dynamic Impedance | 0.22 Ω typical - ensures minimal output voltage perturbation under transient load steps in closed-loop systems |
| Temperature Range | –40 °C to +125 °C - meets automotive AEC-Q100 Grade 1 requirements for under-hood and battery management applications |
| Cathode-Anode Voltage | 37 V maximum - defines safe operating area for use with 24 V/48 V bus-derived auxiliary supplies |
| Reference Input Current | ≤6.5 µA max - minimizes divider network power loss and improves high-impedance sensing accuracy |
Pinout & Package
TL431IZT is supplied in TO-92 plastic package (bulk or tape-and-reel), with 3 leads: Anode (pin 1), Cathode (pin 2), Reference (pin 3). Thermal resistance is 200 °C/W junction-to-ambient, requiring PCB copper area for thermal management above 50 mA continuous operation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (Pin 1) | Ground reference terminal | Connects to system ground or return path; forms current sink path with cathode |
| Cathode (Pin 2) | Current-sinking output | Sinks regulated current to maintain REF pin at 2.5 V; drives optocoupler LED or error amplifier input |
| Reference (Pin 3) | Feedback sense input | High-impedance input monitoring resistor divider; triggers regulation when voltage reaches 2.5 V |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q100 qualification | Validated for automotive Grade 1 (–40 °C to +125 °C) per stress test protocol - enables use in ASIL-B compliant power modules |
| Adjustable output via resistive divider | Two external resistors set output without trimming - reduces BOM count and eliminates factory calibration |
| Low dynamic impedance | 0.22 Ω typical - maintains tight output regulation during fast load transients in switching regulators |
| Wide cathode current range | 1–100 mA operational window - accommodates both low-power feedback and higher-current gate driver biasing |
| Stable over full temperature range | ≤30 mV reference deviation from –40 °C to +125 °C - ensures consistent loop gain and output accuracy in extreme environments |
Applications
| Automotive DC-DC Converter | Industrial Isolated Power Supply |
|---|---|
|
Use Scenario: Secondary-side voltage regulation in 12 V→5 V flyback converter for ADAS camera module. IC Role / Device Role / Timing Role: Shunt reference providing feedback signal to optocoupler, closing primary-side control loop. Use Value: Enables ±2% output accuracy across –40 °C to +105 °C ambient while maintaining 0.22 Ω impedance for stable loop phase margin. |
Use Scenario: Output voltage setting in 48 V→24 V industrial SMPS powering PLC I/O modules. IC Role / Device Role / Timing Role: Precision shunt reference driving PC817 optocoupler to isolate feedback path from primary side. Use Value: Supports 36 V maximum output programming and 100 mA sink capability to drive optocoupler LED directly without buffer transistor. |
| On-Board Charger Feedback | Battery Management System Reference |
|
Use Scenario: Voltage regulation for auxiliary 12 V rail in EV on-board charger (OBC) control board. IC Role / Device Role / Timing Role: Adjustable shunt reference generating stable 3.3 V for microcontroller ADC reference and communication ICs. Use Value: AEC-Q100 qualification and 125 °C operation ensure reliability in high-temperature OBC enclosures near power stages. |
Use Scenario: Reference source for cell voltage monitoring circuit in 48 V mild-hybrid battery pack. IC Role / Device Role / Timing Role: High-stability 2.5 V reference feeding multiplexer and 16-bit ADC for precise cell voltage digitization. Use Value: ≤6.5 µA reference input current minimizes loading on high-resistance voltage divider, preserving measurement 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 | 1% initial accuracy, same TO-92 package and –40 °C to +105 °C range | Used in non-automotive industrial supplies where tighter tolerance justifies cost premium | Select when ±1% output accuracy is required and extended automotive temperature range is not needed |
| TL431BIL3T | 0.5% accuracy, SOT23-3 package, –40 °C to +125 °C, lower thermal resistance (248 °C/W) | Preferred for space-constrained automotive modules needing highest voltage precision | Choose for compact layouts requiring 0.5% reference accuracy and full AEC-Q100 Grade 1 support |
Compared with TL431IZT, TL431ACZ trades automotive temperature range for tighter 1% accuracy, while TL431BIL3T offers superior 0.5% precision and smaller SOT23-3 footprint but requires re-layout due to different pinout and thermal interface design.
Availability
TL431IZT is available at Aetrix Electronics and suitable for automotive power conversion, industrial isolated SMPS, and battery management systems requiring stable component supply with guaranteed AEC-Q100 qualification and long-term production continuity.
Supply support for TL431IZT 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, MCU, power, and sensor solutions for automotive, industrial, and consumer markets.
TL431IZT belongs to ST's precision analog voltage reference product line, engineered specifically for automotive-grade feedback stability, high-temperature reliability, and compatibility with optocoupler-based isolation architectures.
FAQ
What is the maximum cathode-to-anode voltage for TL431IZT?
The absolute maximum cathode-to-anode voltage (VKA) is 37 V, as specified in Table 1 of the STMicroelectronics datasheet (DocID4467 Rev 17). Exceeding this value risks permanent damage. Designers must ensure worst-case output transients - including reflected spikes in flyback topologies - remain below this limit, typically by adding clamping Zener diodes or snubbers.
Does TL431IZT require an external capacitor for stability?
TL431IZT does not require an external compensation capacitor for basic operation, but stability with capacitive loads depends on circuit configuration. Figure 21 in the datasheet shows it remains stable with ≥10 nF load capacitance when used with standard optocoupler feedback networks. For >100 nF loads or high-frequency loops, a series resistor (10–100 Ω) between cathode and optocoupler LED is recommended to dampen resonance.
How does TL431IZT differ from TL431CD in automotive use?
TL431IZT is AEC-Q100 qualified with –40 °C to +125 °C operation and 2% accuracy, whereas TL431CD is commercial-grade (0 °C to +70 °C) with identical electrical specs but no automotive qualification. TL431IZT undergoes extended stress testing (HTOL, TC, UHAST) and has controlled process lot traceability - mandatory for automotive Tier 1 suppliers.
Can TL431IZT be used in series with another TL431 for higher voltage reference?
No - TL431IZT is a shunt regulator, not a series reference. Connecting two in series violates the anode-ground requirement and disrupts internal biasing. For >36 V references, use a precision resistor divider with TL431IZT's REF pin, or select a dedicated high-voltage series reference like the MAX6012. The device's 37 V VKA max also prohibits cascading.
TL431IZT 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):
- 2.495V
- 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:
- Through Hole
- Supplier Device Package:
- TO-92-3
TL431IZT FAQ
1.How can I place an order for TL431IZT through Aetrix?
Please submit a Request for Quotation (RFQ) for TL431IZT 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 TL431IZT reliable?
The price and inventory of TL431IZT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for TL431IZT is usually 5 days.
3.What payment methods are accepted for TL431IZT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for TL431IZT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for TL431IZT?
TL431IZT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your TL431IZT 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 TL431IZT?
For technical support, including TL431IZT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your TL431IZT requirements.
6.How does Aetrix verify that TL431IZT is sourced from the original manufacturer or authorized distributors?
All TL431IZT 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 TL431IZT meets industry standards.
7.What is the process for return or replacement of TL431IZT?
All TL431IZT units undergo pre-shipment inspection (PSI). If there is an issue with TL431IZT, 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 TL431IZT part is unused and in its original packaging.
Return procedure for TL431IZT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
TL431IZT Tags
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