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STMicroelectronics TL1431CZT
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- Part No.:
- TL1431CZT
- Manufacturer:
- STMicroelectronics
- Category:
- Voltage Reference
- Package:
- TO-226-2, TO-92-2 (TO-226AC)
- Datasheet:
-
TL1431CZT.pdf
- Description:
- IC VREF SHUNT ADJ 0.4% TO92-3
- Quantity:
- Payment:
- Shipping:
Inventory:6,250
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Product details
Overview
TL1431CZT from STMicroelectronics is a precision adjustable shunt voltage reference IC with 0.4% initial voltage accuracy, 2.5 V to 36 V programmable output range via two external resistors, and guaranteed operation from –20 °C to +70 °C. It delivers 1–100 mA sink current capability with 0.22 Ω typical dynamic impedance and supports automotive-grade feedback loops in isolated DC-DC converters.
For engineers reviewing the TL1431CZT datasheet, TL1431CZT pinout, TL1431CZT application, or TL1431CZT equivalent, key selection criteria include its TO-92 package mechanical compatibility, temperature-stable reference deviation (±3 mV over full range), low reference input current (1.5–3 µA), and suitability for closed-loop voltage regulation in power supply feedback networks.
Technical Context
The TL1431CZT implements a bandgap-based reference core with internal error amplifier and NPN pass transistor, configured as a 3-terminal shunt regulator. Its cathode-anode voltage regulation is set by external resistor dividers connected to the REF pin, enabling precise output voltage synthesis without requiring a dedicated reference IC or op-amp.
It operates in continuous conduction mode across 1–100 mA cathode current, maintains stable regulation down to 0.5 mA minimum cathode current, and exhibits <0.5 Ω dynamic impedance up to 1 kHz - critical for suppressing ripple in switching power supply 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 Range | 2.5 V to 36 V - programmable via external R1/R2 divider; enables flexible voltage scaling |
| Sink Current | 1–100 mA - defines usable load range for feedback loop current sourcing |
| Dynamic Impedance | 0.2–0.5 Ω - determines AC ripple rejection performance in high-frequency switching supplies |
| Temp. Coefficient | ±13 ppm/°C - ensures <±0.3 mV drift over 0–70 °C ambient, critical for stable feedback |
| Ref Input Current | 1.5–3 µA - low bias current minimizes divider resistor power loss and thermal drift |
| Voltage Deviation | ±3 mV over –20 to +70 °C - guarantees tight output tolerance without external calibration |
Pinout & Package
TL1431CZT uses the TO-92 plastic package (3-pin, through-hole), with standardized lead configuration: Cathode (pin 1), Anode (pin 2), Reference (pin 3). The package supports manual soldering and wave soldering per JEDEC J-STD-020.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode (Pin 1) | Current sink node | Connects to primary-side feedback winding or optocoupler anode; carries full regulation current |
| Anode (Pin 2) | Ground return path | Common reference point for cathode and REF; must be low-impedance to avoid regulation error |
| REF (Pin 3) | Feedback sense input | High-impedance node monitoring divided output voltage; sets regulation threshold via R1/R2 ratio |
Key Features
| Feature | Design Value |
|---|---|
| Adjustable output voltage | 2.5 V to 36 V via external resistors - eliminates need for multiple fixed-reference parts |
| Low dynamic impedance | 0.22 Ω typical - improves transient response and reduces output ripple in SMPS feedback |
| Stable reference deviation | ±3 mV over –20 to +70 °C - enables single-point calibration in cost-sensitive industrial designs |
| Wide sink current range | 1–100 mA - accommodates both low-power optocoupler drive and direct MOSFET gate control |
| Low reference input current | 1.5–3 µA - allows use of high-value divider resistors (>100 kΩ), reducing power consumption |
Applications
| Isolated Flyback Converter | Programmable Linear Regulator |
|---|---|
Use Scenario: Secondary-side voltage sensing in 12 V/5 V isolated flyback power supplies with optocoupler feedback. IC Role / Device Role / Timing Role: Shunt reference providing precise 2.5 V threshold to drive optocoupler LED; regulates primary-side PWM duty cycle via feedback loop. Use Value: Enables ±1% output voltage accuracy across line/load/temperature with minimal BOM count and no secondary-side LDO. | Use Scenario: Adjustable 3.3–15 V linear regulator using PNP pass transistor and external resistive divider. IC Role / Device Role / Timing Role: Precision reference element setting base-emitter voltage of series pass transistor; defines output voltage setpoint. Use Value: Achieves 0.4% initial accuracy and <±5 mV total drift over temperature - superior to standard Zener diodes. |
| Overvoltage Protection Circuit | Battery Charger Feedback |
Use Scenario: Monitoring 24 V rail in industrial PLC I/O modules; triggers crowbar or shutdown above 26.5 V. IC Role / Device Role / Timing Role: Adjustable voltage comparator reference; drives SCR gate or logic-level shutdown signal when threshold exceeded. Use Value: Programmable trip point avoids custom resistor networks; 0.22 Ω impedance ensures fast response to overvoltage transients. | Use Scenario: Voltage regulation in 3-cell Li-ion charger (12.6 V max) with thermistor-compensated termination. IC Role / Device Role / Timing Role: Precision reference for ADC input scaling and charge voltage DAC reference in analog front-end. Use Value: 1.5–3 µA reference current minimizes self-heating error during long-term float charging at elevated ambient temperatures. |
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, identical pinout | Higher precision required in medical-grade power supplies where ±1.25 mV reference deviation is mandatory | Select when tighter initial tolerance justifies higher unit cost and qualification revalidation |
| LM4040CIM3-ADJ | Fixed 2.5 V reference only; requires external op-amp for adjustability; SOT-23-3 package | Used in space-constrained PCBs where footprint reduction outweighs need for integrated adjustability | Choose only if design already includes rail-to-rail op-amp and board area is critical |
Compared with TL431ACZ, TL1431CZT trades 0.15% accuracy for broader commercial temperature support and lower cost; versus LM4040CIM3-ADJ, it integrates regulation functionality without external active components, simplifying feedback design but occupying larger TO-92 footprint.
Availability
TL1431CZT is available at Aetrix Electronics and suitable for isolated DC-DC converters, programmable linear regulators, and overvoltage protection circuits requiring stable component supply and long-term manufacturability.
Supply support for TL1431CZT 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, analog chips, and MEMS sensors for industrial, automotive, and consumer markets.
The TL1431 belongs to ST's precision analog reference product line, engineered specifically for high-reliability feedback control in power conversion systems where stability, accuracy, and thermal robustness are essential.
FAQ
What is the minimum cathode current required for stable regulation in TL1431CZT?
The TL1431CZT requires a minimum cathode current of 0.5 mA to maintain regulation, verified across –20 °C to +70 °C. Below this threshold, output voltage deviates beyond specification; typical designs use ≥1 mA to ensure margin under worst-case temperature and supply conditions.
Can TL1431CZT replace a Zener diode in existing designs?
Yes - TL1431CZT replaces standard Zener diodes in shunt regulator applications with superior performance: 0.4% initial accuracy vs. ±5% for 5.1 V Zeners, 0.22 Ω dynamic impedance vs. >10 Ω for Zeners, and programmable output without changing component values.
Does TL1431CZT require external compensation for stability?
No external compensation is needed for basic shunt regulation. However, when driving capacitive loads >10 nF or used with optocouplers having significant CTR variation, a 100 pF–1 nF capacitor between REF and cathode improves phase margin and prevents oscillation, per Figure 20 in the datasheet.
What is the maximum power dissipation of TL1431CZT in TO-92 package?
In TO-92 package, TL1431CZT has a maximum power dissipation of 625 mW at 25 °C ambient, calculated using junction-to-ambient thermal resistance of 200 °C/W. Derating is required above 25 °C - e.g., 400 mW at 65 °C ambient - to keep junction temperature ≤150 °C.
TL1431CZT 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):
- 2.5V
- 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
TL1431CZT FAQ
1.How can I place an order for TL1431CZT through Aetrix?
Please submit a Request for Quotation (RFQ) for TL1431CZT 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 TL1431CZT reliable?
The price and inventory of TL1431CZT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for TL1431CZT is usually 5 days.
3.What payment methods are accepted for TL1431CZT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for TL1431CZT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for TL1431CZT?
TL1431CZT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your TL1431CZT 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 TL1431CZT?
For technical support, including TL1431CZT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your TL1431CZT requirements.
6.How does Aetrix verify that TL1431CZT is sourced from the original manufacturer or authorized distributors?
All TL1431CZT 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 TL1431CZT meets industry standards.
7.What is the process for return or replacement of TL1431CZT?
All TL1431CZT units undergo pre-shipment inspection (PSI). If there is an issue with TL1431CZT, 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 TL1431CZT part is unused and in its original packaging.
Return procedure for TL1431CZT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
TL1431CZT Tags
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TL431AIDBZR
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TL431BQDBZR
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AN431AN-ATRG1
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LM4040CYM3-2.5-TR
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AZ431LBNTR-G1
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LM4041DIM3-ADJ/NOPB
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LM4040DIM3X-2.5/NOPB
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LM4040DIM3-2.5/NOPB
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AZ431LANTR-G1
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