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Texas Instruments TL431BCDR
- Part No.:
- TL431BCDR
- Manufacturer:
- Texas Instruments
- Category:
- Voltage Reference
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
TL431BCDR.pdf
- Description:
- IC VREF SHUNT ADJ 0.5% 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,748
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Product details
Overview
TL431BCDR from Texas Instruments is a precision programmable shunt voltage reference in SOT-23-3 package, featuring 0.5% initial reference voltage tolerance at 25°C (2.483–2.507 V), adjustable output from 2.5 V to 36 V, and operation across −40°C to 125°C. It delivers 0.2 Ω typical dynamic impedance and supports 1–100 mA sink current, widely used in isolated feedback loops of AC/DC adapters and industrial power supplies.
For engineers reviewing the TL431BCDR datasheet, TL431BCDR pinout, TL431BCDR application, or TL431BCDR equivalent, key selection criteria include reference accuracy grade (B), thermal stability over extended temperature range (Q-grade), low-noise performance, and compatibility with standard resistor-divider feedback networks in switching regulator designs.
Technical Context
The TL431BCDR implements a three-terminal adjustable shunt regulator architecture with an internal error amplifier, reference, and output transistor. Its REF pin senses voltage relative to ANODE, enabling precise regulation via external resistive divider while maintaining sharp turn-on characteristics similar to Zener diodes-but with superior thermal drift control and lower output impedance.
Designed for high-stability feedback paths, it operates with cathode-to-anode voltage (VKA) from Vref up to 36 V and requires minimum cathode current (Imin) of 0.4–0.6 mA for regulation. The device exhibits low temperature coefficient-VI(dev) ≤ 14 mV over −40°C to 125°C-and maintains stable dynamic impedance (<0.5 Ω) up to 1 kHz.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reference Voltage | 2.483–2.507 V at 25°C - enables accurate setpoint definition for feedback networks in regulated power supplies |
| Initial Tolerance | ±0.5% (B grade) - ensures tight output voltage control without trimming in production systems |
| Operating Temp Range | −40°C to 125°C (Q-grade) - supports automotive and industrial environments where ambient extremes challenge regulation stability |
| Dynamic Impedance | 0.2 Ω typical - minimizes output voltage variation under load transients in closed-loop feedback applications |
| Sink Current Range | 1–100 mA - accommodates wide-range optocoupler LED drive and secondary-side error amplification in isolated converters |
| Reference Input Current | 2–4 µA - allows use of high-value feedback resistors (>1 MΩ), reducing power loss and improving efficiency |
| Temp Drift (VI(dev)) | ≤14 mV over full range - guarantees <0.06%/°C effective TC, critical for long-term output accuracy in unregulated input conditions |
Pinout & Package
SOT-23-3 package (2.90 mm × 1.30 mm), surface-mount, RoHS-compliant, with gull-wing leads and exposed pad not connected internally.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 (CATHODE) | Shunt current output node | Connects to primary-side controller feedback (e.g., UC384x COMP pin) or optocoupler anode; sinks regulated current |
| Pin 2 (ANODE) | Common reference return | Typically tied to system ground or power supply return; serves as voltage reference point for REF pin measurement |
| Pin 3 (REF) | Threshold input | Monitors divided output voltage; triggers regulation when input reaches ~2.495 V relative to ANODE |
Key Features
| Feature | Design Value |
|---|---|
| High-accuracy reference | 0.5% initial tolerance enables ±1% output voltage regulation without calibration in SMPS designs |
| Wide adjustment range | 2.5 V to 36 V output via two-resistor divider - supports universal input AC/DC and multi-rail DC/DC topologies |
| Low dynamic impedance | 0.2 Ω typical improves loop stability and reduces sensitivity to PCB trace inductance in fast transient response |
| Extended temperature operation | Rated for −40°C to 125°C junction temperature - qualified for under-hood automotive and industrial motor drive applications |
| Low reference current | 2–4 µA input current permits >1 MΩ feedback dividers - lowers standby power and improves light-load efficiency |
Applications
| Rack Server Power | Industrial AC/DC Converter |
|---|---|
|
Use Scenario: Secondary-side voltage sensing in 48 V input, 12 V/50 A isolated DC/DC module for telecom rectifiers. IC Role / Device Role / Timing Role: Shunt reference providing feedback signal to optocoupler, closing regulation loop across isolation barrier. Use Value: 0.5% reference accuracy ensures ±0.6 V output tolerance at 12 V; low temp drift prevents derating over chassis temperature gradients. |
Use Scenario: Output voltage regulation in 3-phase industrial AC/DC front-end supplying 24 V control rail. IC Role / Device Role / Timing Role: Precision shunt reference setting feedback threshold for UCC28070 PFC controller secondary-side error amp. Use Value: 100 mA sink capability drives high-CTR optocoupler directly; SOT-23-3 footprint saves space on crowded control board. |
| AC Inverter Drive | Notebook PC Adapter |
|
Use Scenario: Auxiliary 15 V rail regulation in IGBT gate driver power supply within servo inverter stack. IC Role / Device Role / Timing Role: Stable reference for TL431-based linear post-regulator feeding isolated gate driver ICs. Use Value: 0.2 Ω dynamic impedance suppresses noise coupling into sensitive gate drive paths; Q-temp rating ensures reliability at 110°C ambient. |
Use Scenario: Feedback reference in 19 V, 3.42 A flyback adapter with QR controller (e.g., NCP1342). IC Role / Device Role / Timing Role: Programmable shunt reference replacing discrete Zener + transistor in secondary-side error detection circuit. Use Value: 2–4 µA reference current enables 1.2 MΩ/12 kΩ divider - cuts no-load consumption by 30% vs legacy 100 kΩ network. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar shunt reference applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TL431BIDR | Same B-grade accuracy and SOT-23-3 package, but rated for −40°C to 85°C (I-grade) instead of −40°C to 125°C | Not suitable for under-hood or high-ambient industrial use; acceptable for consumer-grade adapters and server board aux rails | Select TL431BIDR only if operating ambient stays below 85°C and cost optimization is prioritized over extended temp margin |
| TLVH431BQDBVR | Lower 1.24 V reference voltage, 0.5% tolerance, SOT-23-3, but max cathode voltage limited to 18 V (vs 36 V) | Cannot replace TL431BCDR in >18 V output or high-VKA feedback configurations; suited for low-voltage LDO supervision | Choose TLVH431BQDBVR only for sub-18 V regulated rails where reduced headroom and lower reference simplify divider design |
Compared with TL431BIDR and TLVH431BQDBVR, TL431BCDR uniquely combines Q-grade temperature range, 36 V cathode rating, and 0.5% accuracy in SOT-23-3-making it the only direct fit for high-reliability, high-output-voltage isolated feedback where thermal robustness and voltage headroom are non-negotiable.
Availability
TL431BCDR is available at Aetrix Electronics and suitable for rack server power, industrial AC/DC converters, and AC inverter drive systems requiring stable component supply with guaranteed long-term sourcing and consistent parametric performance.
Supply support for TL431BCDR 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
Texas Instruments is a global semiconductor leader delivering analog, embedded processing, and connectivity solutions with emphasis on reliability, energy efficiency, and system-level integration.
The TL431 product line delivers precision programmable shunt references for feedback control in power conversion systems, designed specifically to replace Zener diodes with higher accuracy, better thermal stability, and wider operating range.
FAQ
What is the reference voltage tolerance of TL431BCDR at 25°C?
The TL431BCDR has a reference voltage tolerance of ±0.5% at 25°C, corresponding to a nominal 2.495 V output with a specified range of 2.483 V to 2.507 V. This B-grade accuracy is confirmed in Section 6.11 of the TI SLVS543S datasheet and applies strictly to the TL431BCDR variant under recommended operating conditions with 10 mA cathode current.
Does TL431BCDR support operation at 125°C junction temperature?
Yes, TL431BCDR is a Q-grade device characterized for operation from −40°C to 125°C ambient temperature, with maximum junction temperature rated at 150°C. Its electrical specifications-including reference voltage deviation (VI(dev) ≤ 14 mV) and dynamic impedance-are guaranteed across this full range, making it suitable for high-temperature industrial and automotive under-hood applications.
What is the minimum cathode current required for regulation in TL431BCDR?
The TL431BCDR requires a minimum cathode current (Imin) of 0.4–0.6 mA to maintain regulation, per Section 6.11 of the datasheet. This value is lower than standard-grade TL431 devices and enables stable operation even with high-impedance feedback networks or low-power optocouplers commonly used in energy-efficient adapters.
Can TL431BCDR replace a Zener diode in feedback circuits?
Yes, TL431BCDR is explicitly designed as a precision replacement for Zener diodes in voltage regulation and feedback applications. Its sharp turn-on characteristic, 0.2 Ω dynamic impedance, and 0.5% reference accuracy provide superior regulation stability, especially in switching power supplies where Zener voltage drift and impedance limitations degrade performance.
What package type is used for TL431BCDR?
TL431BCDR uses the SOT-23-3 package (2.90 mm × 1.30 mm body size), with pinout CATHODE–ANODE–REF (Pin 1–2–3). This compact, surface-mount package is RoHS-compliant and optimized for automated assembly in space-constrained power supply control boards.
TL431BCDR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- 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:
- ±0.5%
- Temperature Coefficient:
- -
- Noise - 0.1Hz to 10Hz:
- -
- Noise - 10Hz to 10kHz:
- -
- Voltage - Input:
- -
- Current - Supply:
- -
- Current - Cathode:
- 600 µA
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
TL431BCDR FAQ
1.How can I place an order for TL431BCDR through Aetrix?
Please submit a Request for Quotation (RFQ) for TL431BCDR 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 TL431BCDR reliable?
The price and inventory of TL431BCDR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for TL431BCDR is usually 5 days.
3.What payment methods are accepted for TL431BCDR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for TL431BCDR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for TL431BCDR?
TL431BCDR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your TL431BCDR 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 TL431BCDR?
For technical support, including TL431BCDR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your TL431BCDR requirements.
6.How does Aetrix verify that TL431BCDR is sourced from the original manufacturer or authorized distributors?
All TL431BCDR 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 TL431BCDR meets industry standards.
7.What is the process for return or replacement of TL431BCDR?
All TL431BCDR units undergo pre-shipment inspection (PSI). If there is an issue with TL431BCDR, 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 TL431BCDR part is unused and in its original packaging.
Return procedure for TL431BCDR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
TL431BCDR 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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LM4040CYM3-4.1-TR
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LM4040EIM3-2.5/NOPB
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AZ431LBNTR-G1
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LM4040D20IDBZR
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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
Diodes Incorporated
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