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STMicroelectronics TL1431CZ
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- Part No.:
- TL1431CZ
- Manufacturer:
- STMicroelectronics
- Category:
- Voltage Reference
- Package:
- TO-226-2, TO-92-2 (TO-226AC)
- Datasheet:
-
TL1431CZ.pdf
- Description:
- IC VREF SHUNT ADJ 0.4% TO92-3
- Quantity:
- Payment:
- Shipping:
Inventory:883
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Product details
Overview
TL1431CZ 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, and guaranteed operation from –20 °C to +70 °C. It delivers 1–100 mA sink current with 0.22 Ω typical dynamic impedance and supports precision feedback in isolated DC-DC converters and linear regulator circuits.
For engineers reviewing the TL1431CZ datasheet, TL1431CZ pinout, TL1431CZ application, or TL1431CZ equivalent, key selection considerations include its TO-92 package mechanical compatibility, cathode/anode/reference terminal roles, temperature-stable 2.5 V internal reference, and suitability for low-cost voltage regulation where ±0.4% accuracy and automotive-grade thermal margin are required.
Technical Context
The TL1431CZ implements a bandgap-referenced error amplifier driving an NPN output stage in a three-terminal shunt topology. Its reference input (REF) senses a resistor divider across the cathode–anode path, enabling precise closed-loop regulation independent of input voltage variations up to 36 V.
It operates as a 2.5 V precision reference with <±13 ppm/°C temperature coefficient and maintains regulation down to 0.5 mA minimum cathode current. Dynamic impedance remains ≤0.5 Ω across 1–100 mA sink current and up to 1 kHz, ensuring stable loop response in feedback networks.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reference Voltage | 2.500 V ±0.4% at 10 mA cathode current - defines base accuracy for external resistor-divider programming |
| Output Voltage Range | 2.5 V to 36 V - set by R1/R2 ratio; enables flexible regulation without dedicated ICs |
| Sink Current Range | 1 mA to 100 mA - supports direct drive of optocoupler LEDs or error amplifier biasing |
| Dynamic Impedance | 0.22 Ω typical - ensures minimal output voltage perturbation under load transients |
| Temp. Coefficient | ±13 ppm/°C - guarantees <±3 mV drift over –20 °C to +70 °C operating range |
| Ref Input Current | 1.5–3.0 µA - low bias requirement simplifies high-impedance feedback network design |
| Min. Cathode Current | 0.5 mA - enables stable regulation even in ultra-low-power standby modes |
Pinout & Package
TL1431CZ is supplied in TO-92 plastic package (bulk or ammopack), with 3 leads: Anode (pin 1), Cathode (pin 2), and Reference (pin 3). Pin 1 connects to system ground or return path; pin 2 carries regulated sink current; pin 3 provides high-impedance reference input for external resistor divider.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (Pin 1) | Ground reference node | Return path for cathode current; tied to system GND or negative rail in shunt configuration |
| Cathode (Pin 2) | Regulated current sink output | Carries full load current; voltage at this pin is controlled relative to anode via REF feedback |
| Reference (Pin 3) | High-impedance error amplifier input | Senses voltage divider output; draws only ~2.5 µA; sets regulation point when = 2.5 V |
Key Features
| Feature | Design Value |
|---|---|
| Adjustable output voltage | Programmable from 2.5 V to 36 V using two external resistors - eliminates need for multiple fixed-reference parts |
| Voltage precision | 0.4% initial tolerance - reduces calibration overhead in production test for power supply modules |
| Low dynamic impedance | 0.22 Ω typical - minimizes output voltage ripple under fast load steps in SMPS feedback loops |
| Wide sink current range | 1–100 mA operation - accommodates both low-power sensing and higher-current optocoupler drive |
| Stable over temperature | Specified from –20 °C to +70 °C - ensures consistent performance in industrial and consumer ambient environments |
Applications
| Isolated Flyback Converter Feedback | Adjustable Linear Regulator Reference |
|---|---|
|
Use Scenario: Secondary-side voltage sensing in AC/DC flyback converters using optocoupler-coupled feedback. IC Role / Device Role / Timing Role: Shunt reference providing precise 2.5 V threshold to drive optocoupler LED; regulates primary-side controller via isolated signal path. Use Value: Enables ±1% output voltage regulation without secondary-side LDO; leverages 0.4% reference accuracy and low 2.5 µA input current to minimize divider power loss. |
Use Scenario: Precision voltage setting in low-dropout linear regulators with external pass transistor. IC Role / Device Role / Timing Role: Adjustable reference source feeding error amplifier; determines regulated output via R1/R2 scaling. Use Value: Replaces fixed 2.5 V references to support custom output voltages (e.g., 5.0 V, 12.0 V) while maintaining <±0.4% accuracy and <±3 mV tempco drift. |
| Battery Charger Voltage Monitor | Industrial Sensor Excitation Supply |
|
Use Scenario: Overvoltage protection and charge termination detection in lead-acid or LiFePO₄ battery chargers. IC Role / Device Role / Timing Role: Programmable shunt clamp that triggers cutoff when battery voltage exceeds setpoint defined by R1/R2. Use Value: Provides accurate, temperature-stable trip point (e.g., 14.4 V ±0.06 V) using only passive components; 100 mA sink capability handles transient overvoltage energy. |
Use Scenario: Stable excitation voltage for resistive bridge sensors (e.g., strain gauges, RTDs) in PLC analog input modules. IC Role / Device Role / Timing Role: Low-drift, low-noise reference source powering sensor bridges; rejects supply ripple via shunt topology. Use Value: Delivers 2.5 V ±0.01 V stability over –20 °C to +70 °C, reducing measurement offset errors caused by reference drift in 24-bit ADC systems. |
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 | 0.25% initial accuracy, same TO-92 package and pinout | Higher precision required in metrology-grade power supplies or calibration equipment | Select when tighter initial tolerance justifies cost premium; identical layout and thermal behavior |
| LM431ACZ | 0.5% accuracy, 1.0 µA max reference current, wider –40 °C to +85 °C range | Cost-sensitive consumer applications needing broader temperature coverage but relaxed accuracy | Choose for legacy designs or price-driven volume production where ±0.5% is acceptable |
Compared with TL431ACZ, TL1431CZ trades 0.15% accuracy for lower unit cost and identical footprint; versus LM431ACZ, it improves initial tolerance by 0.1% and reduces reference current by 40%, enhancing high-impedance divider stability.
Availability
TL1431CZ is available at Aetrix Electronics and suitable for isolated DC-DC converters, adjustable linear regulators, and battery voltage monitors requiring stable component supply with TO-92 through-hole compatibility and long-term manufacturing continuity.
Supply support for TL1431CZ 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 management ICs, and analog components for industrial, automotive, and consumer markets.
TL1431CZ belongs to ST's precision analog voltage reference product line, engineered specifically for cost-effective, high-accuracy shunt regulation in power supply feedback, sensing, and protection circuits.
FAQ
What is the maximum cathode-to-anode voltage for TL1431CZ?
The absolute maximum cathode-to-anode voltage is 37 V. Operation above 36 V risks exceeding safe operating area limits and may cause irreversible damage. For reliable long-term use, design cathode voltage to remain ≤36 V under all conditions including transients and startup surges.
Can TL1431CZ replace TL431 in existing designs?
Yes - TL1431CZ is pin-compatible and functionally equivalent to TL431 in TO-92 packages. Key differences include slightly lower dynamic impedance (0.22 Ω vs. 0.25 Ω typical) and identical electrical specifications except for minor parameter binning. No layout or schematic changes are needed for drop-in replacement.
How does the reference input current affect resistor divider design?
TL1431CZ draws 1.5–3.0 µA into the REF pin. To limit divider-induced error to <0.1%, total divider resistance should be ≤25 kΩ (e.g., 10 kΩ + 15 kΩ). Higher values increase sensitivity to leakage and noise; lower values increase power dissipation without improving accuracy.
Is TL1431CZ qualified for automotive applications?
No - TL1431CZ is rated for –20 °C to +70 °C and is intended for commercial/industrial use. For automotive applications, ST offers TL1431IY (–40 °C to +125 °C, AEC-Q100 qualified) in SO-8 and TO-92 variants, which share identical electrical characteristics but undergo extended reliability testing.
TL1431CZ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Package/Case:
- TO-226-2, TO-92-2 (TO-226AC)
- Series:
- -
- Packaging:
- Bulk
- Product Status:
- Obsolete
- 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:
- 90ppm/°C
- Noise - 0.1Hz to 10Hz:
- -
- Noise - 10Hz to 10kHz:
- -
- Voltage - Input:
- -
- Current - Supply:
- -
- Current - Cathode:
- 1 mA
- Operating Temperature:
- -20°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-92-3
TL1431CZ FAQ
1.How can I place an order for TL1431CZ through Aetrix?
Please submit a Request for Quotation (RFQ) for TL1431CZ 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 TL1431CZ reliable?
The price and inventory of TL1431CZ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for TL1431CZ is usually 5 days.
3.What payment methods are accepted for TL1431CZ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for TL1431CZ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for TL1431CZ?
TL1431CZ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your TL1431CZ 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 TL1431CZ?
For technical support, including TL1431CZ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your TL1431CZ requirements.
6.How does Aetrix verify that TL1431CZ is sourced from the original manufacturer or authorized distributors?
All TL1431CZ 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 TL1431CZ meets industry standards.
7.What is the process for return or replacement of TL1431CZ?
All TL1431CZ units undergo pre-shipment inspection (PSI). If there is an issue with TL1431CZ, 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 TL1431CZ part is unused and in its original packaging.
Return procedure for TL1431CZ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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