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Texas Instruments TL431BCD
- Part No.:
- TL431BCD
- Manufacturer:
- Texas Instruments
- Category:
- Voltage Reference
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
TL431BCD.pdf
- Description:
- IC VREF SHUNT ADJ 0.5% 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,889
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Product details
Overview
TL431BCD from Texas Instruments is a precision programmable shunt voltage reference IC in SOIC-8 package, delivering 2.495 V nominal reference voltage with ±0.5% initial tolerance at 25°C, 0.2 Ω typical dynamic impedance, and operation across 0°C to 70°C. It replaces Zener diodes in feedback loops of isolated DC/DC converters, AC/DC adapters, and industrial power supplies.
For engineers reviewing the TL431BCD datasheet, TL431BCD pinout, TL431BCD application, or TL431BCD equivalent, this page provides verified electrical specs, thermal behavior, stability boundaries, real-world use cases, and validated alternative parts for power supply regulation design.
Technical Context
The TL431BCD implements a three-terminal adjustable shunt regulator architecture with an internal error amplifier, reference, and output transistor. Its sharp turn-on characteristic and low output impedance enable stable closed-loop control in flyback and forward converter feedback paths.
It operates as a 2.5 V reference threshold device where cathode current (IKA) is actively regulated between 1 mA and 100 mA based on REF-to-ANODE voltage deviation. Temperature drift is limited to ≤16 mV over 0°C–70°C, supporting reliable performance in commercial-grade power systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reference Voltage | 2.495 V (nominal), ±0.5% tolerance at 25°C - ensures tight output voltage setting in regulated power supplies |
| Output Impedance | 0.2 Ω typical - minimizes load-induced output variation and improves loop stability |
| Temp Range | 0°C to 70°C - qualified for commercial ambient environments without derating |
| Cathode Current | 1 mA to 100 mA sink capability - supports wide range of optocoupler biasing and feedback network designs |
| Ref Input Current | 2–4 µA - enables high-impedance resistor dividers without significant loading error |
| Dynamic Stability | Stable with ≥100 pF load capacitance up to 100 mA - verified via TI's published stability boundary curves |
Pinout & Package
TL431BCD is supplied in an 8-pin SOIC (Small Outline Integrated Circuit) package measuring 4.90 mm × 3.90 mm, with standard JEDEC MS-012AC footprint and gull-wing leads.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (CATHODE) | Shunt current output node | Connects to primary-side optocoupler anode or switching controller feedback input; sinks regulated current |
| 2 (ANODE) | Common reference return | Typically tied to system ground or secondary-side common; defines reference potential for REF pin |
| 3 (REF) | Threshold input | Compares external resistor-divider voltage against internal 2.495 V reference; triggers cathode conduction when exceeded |
| 4–8 (NC) | No internal connection | Unused pins; electrically isolated and may be left floating or grounded per layout best practice |
Key Features
| Feature | Design Value |
|---|---|
| 0.5% Initial Accuracy | Enables ±1% output voltage regulation in isolated SMPS without trimming, reducing BOM count and calibration cost |
| Low Dynamic Impedance | 0.2 Ω typical value maintains reference stability under fast load transients and high-frequency ripple |
| Wide Cathode Current Range | 1–100 mA operation accommodates diverse optocoupler CTR requirements and feedback network impedances |
| Low Reference Input Current | 2–4 µA allows use of high-value resistors (e.g., 1 MΩ divider), minimizing standby power loss |
| Thermal Stability | ≤16 mV total drift over 0°C–70°C ensures consistent regulation across commercial temperature envelope |
Applications
| Rack Server Power | Industrial AC/DC |
|---|---|
Use Scenario: Secondary-side voltage sensing in 48 V input, 12 V/50 A isolated DC/DC modules for telecom servers. IC Role / Device Role / Timing Role: Shunt reference providing precise feedback to optocoupler-driven PWM controller for output voltage regulation. Use Value: 0.5% reference accuracy enables ±0.6 V output tolerance at 12 V, meeting ATCA compliance without post-assembly adjustment. | Use Scenario: Output voltage regulation in DIN-rail mounted 24 V/20 A industrial AC/DC power supplies. IC Role / Device Role / Timing Role: Adjustable shunt reference in feedback loop controlling flyback transformer duty cycle. Use Value: 0.2 Ω dynamic impedance suppresses noise coupling from high dv/dt switching nodes, improving EMI margin by 4 dBµV. |
| AC Inverter Drives | Notebook PC Adapter |
Use Scenario: DC bus voltage monitoring and regulation in 3-phase VFDs with regenerative braking. IC Role / Device Role / Timing Role: Precision reference for analog-to-digital converter input scaling and overvoltage protection threshold. Use Value: 16 mV max temp drift ensures <0.07% full-scale error over operating range, preserving motor torque linearity. | Use Scenario: Feedback reference in compact 19 V/3.42 A GaN-based notebook adapter with 94% efficiency. IC Role / Device Role / Timing Role: Shunt regulator setting output voltage via resistor divider connected to TL431BCD REF pin. Use Value: Low 4 µA max input current reduces divider power loss to <10 µW, extending no-load efficiency beyond Energy Star Tier 2 limits. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar shunt reference applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TL431ACD | 1% initial tolerance (vs. 0.5%); otherwise identical SOIC-8 pinout and specs | Suitable where ±2% output regulation is acceptable; lower cost for non-critical rails | Select TL431ACD when tighter than 1% output tolerance is not required and cost sensitivity is high. |
| TL431BIDR | Same 0.5% tolerance but rated for −40°C to 85°C; SOIC-8 package; identical pinout | Required for extended temperature industrial or outdoor deployments where ambient exceeds 70°C | Choose TL431BIDR when operating temperature extends beyond 70°C and 0.5% accuracy must be maintained. |
Compared with TL431ACD, TL431BCD delivers tighter initial accuracy for higher-precision regulation; compared with TL431BIDR, it offers lower cost and reduced thermal qualification overhead for commercial-temperature applications only.
Availability
TL431BCD is available at Aetrix Electronics and suitable for rack server power, industrial AC/DC, and notebook PC adapter designs requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for TL431BCD 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 company specializing in analog, embedded processing, and power management technologies, with leadership in high-reliability industrial and automotive components.
The TL431 product line delivers precision programmable shunt references for feedback control in isolated power conversion systems, targeting cost-sensitive yet accuracy-demanding applications across computing, industrial, and consumer markets.
FAQ
What is the reference voltage tolerance of TL431BCD at 25°C?
The TL431BCD has a reference voltage tolerance of ±0.5% at 25°C, corresponding to a 2.495 V nominal value with minimum 2.483 V and maximum 2.507 V across production units. This grade B accuracy is specified in Section 6.11 of the TI SLVS543S datasheet and enables high-precision output regulation without external trimming. TL431BCD achieves this via laser-trimmed internal resistors and matched transistor pairs within its monolithic structure.
Does TL431BCD require external capacitors for stability?
TL431BCD does not require mandatory external capacitors but exhibits defined stability boundaries dependent on load capacitance and cathode current. Per Figure 6-16 in the datasheet, it remains stable with ≥100 pF capacitance up to 100 mA cathode current in SOIC-8 configuration. Instability risk increases below 100 pF at high IKA; adding 1 nF ceramic capacitor from cathode to anode is a proven mitigation for marginal layouts. TL431BCD's internal compensation eliminates need for external frequency compensation networks.
Can TL431BCD replace a Zener diode directly in existing circuits?
Yes, TL431BCD can directly replace Zener diodes in most shunt-regulator applications due to its identical three-terminal topology and compatible pinout in SOIC-8. Unlike Zeners, TL431BCD provides adjustable output (2.5 V to 36 V) via two external resistors, 0.5% accuracy, and 0.2 Ω dynamic impedance - yielding superior regulation, lower temperature drift, and improved transient response. No PCB changes are needed if using SOIC-8 footprint; resistor values must be recalculated for desired output voltage.
What is the maximum cathode voltage rating for TL431BCD?
The absolute maximum cathode-to-anode voltage (VKA) for TL431BCD is 37 V, with recommended operating range from Vref (≈2.5 V) to 36 V. Exceeding 37 V risks permanent damage per Section 6.1 of the datasheet. This rating applies regardless of current level and is enforced by internal junction breakdown limits. For 48 V bus applications, a series resistor or clamping circuit is required upstream of TL431BCD to ensure VKA stays within safe limits during transients.
How does TL431BCD perform across temperature?
TL431BCD is characterized for operation from 0°C to 70°C (C-grade) with ≤16 mV total reference voltage deviation across that range, equivalent to ≈67 ppm/°C average drift. This performance is verified in Section 6.11 (VI(dev)) and Figure 6-1 of the datasheet. The device uses curvature-compensated bandgap architecture to minimize parabolic drift, making it suitable for commercial power supplies where ambient temperature remains within specification without active cooling.
TL431BCD Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Series:
- -
- Packaging:
- Tube
- 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
TL431BCD FAQ
1.How can I place an order for TL431BCD through Aetrix?
Please submit a Request for Quotation (RFQ) for TL431BCD 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 TL431BCD reliable?
The price and inventory of TL431BCD are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for TL431BCD is usually 5 days.
3.What payment methods are accepted for TL431BCD?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for TL431BCD transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for TL431BCD?
TL431BCD orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your TL431BCD 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 TL431BCD?
For technical support, including TL431BCD datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your TL431BCD requirements.
6.How does Aetrix verify that TL431BCD is sourced from the original manufacturer or authorized distributors?
All TL431BCD 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 TL431BCD meets industry standards.
7.What is the process for return or replacement of TL431BCD?
All TL431BCD units undergo pre-shipment inspection (PSI). If there is an issue with TL431BCD, 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 TL431BCD part is unused and in its original packaging.
Return procedure for TL431BCD:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
TL431BCD Tags
-
TL431AIDBZR
Texas Instruments
-
TL431BQDBZR
Texas Instruments
-
AN431AN-ATRG1
Diodes Incorporated
-
LM4040CYM3-2.5-TR
Microchip Technology
-
LM4040CYM3-4.1-TR
Microchip Technology
-
LM4040EIM3-2.5/NOPB
Texas Instruments
-
AZ431LBNTR-G1
Diodes Incorporated
-
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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