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Texas Instruments TL431BQPK
- Part No.:
- TL431BQPK
- Manufacturer:
- Texas Instruments
- Category:
- Voltage Reference
- Package:
- TO-243AA
- Datasheet:
-
TL431BQPK.pdf
- Description:
- IC VREF SHUNT ADJ 0.5% SOT89-3
- Quantity:
- Payment:
- Shipping:
Inventory:5,961
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Product details
Overview
TL431BQPK from Texas Instruments is a precision programmable shunt voltage reference in SOT-89 package, delivering 2.495 V nominal reference voltage with ±0.5% initial tolerance at 25°C, 14–34 mV total temperature drift over −40°C to +125°C, and 0.2 Ω typical dynamic impedance. It operates as an adjustable feedback element in isolated DC-DC converters and industrial power supplies requiring high-accuracy regulation.
For engineers reviewing the TL431BQPK datasheet, TL431BQPK pinout, TL431BQPK application, or TL431BQPK equivalent, key selection criteria include automotive-grade temperature range (−40°C to 125°C), B-grade accuracy, SOT-89 thermal performance (RθJC = 9°C/W), and compatibility with optocoupler-based feedback loops in flyback and forward converters.
Technical Context
The TL431BQPK implements a precision bandgap reference core with an internal error amplifier driving a NPN output stage, enabling sharp turn-on and stable shunt regulation across 2.5 V to 36 V output ranges via two external resistors. Its Q-temp qualification confirms operation up to 125°C ambient with guaranteed VI(dev) ≤ 34 mV.
Unlike Zener diodes, it provides active regulation with low output noise (<10 µVRMS over 0.1–10 Hz), minimal cathode current dependency (IKA = 1–100 mA), and predictable dynamic impedance (0.2–0.5 Ω) independent of load current or temperature.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reference Voltage | 2.495 V ±12 mV (B-grade, 25°C); enables precise feedback setpoint for <±1% output regulation in SMPS |
| Initial Tolerance | ±0.5% at 25°C; reduces calibration overhead in factory programming and eliminates trim potentiometers |
| Temp Range | −40°C to +125°C (Q-grade); qualified for under-hood automotive and industrial motor drive applications |
| Dynamic Impedance | 0.2 Ω typical; ensures minimal output voltage perturbation during fast load transients in closed-loop systems |
| Cathode Current | 1–100 mA sink capability; supports direct drive of optocoupler LEDs without external buffer transistors |
| Ref Input Current | 2–4 µA; allows high-value feedback resistor networks (>1 MΩ), reducing power loss and thermal drift |
| Output Noise | ≤10 µVRMS (0.1–10 Hz); critical for low-noise analog sensing and precision ADC reference buffering |
Pinout & Package
SOT-89 (PK) package: 3-pin surface-mount, 4.5 mm × 2.5 mm × 1.5 mm body, exposed thermal pad connected to ANODE for enhanced heat dissipation (RθJC = 9°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| REF (Pin 1) | Reference input | High-impedance threshold node; connects to voltage divider midpoint to set regulated output voltage |
| ANODE (Pin 2) | Common return | Internally tied to substrate; must be connected to system ground or low-side return path |
| CATHODE (Pin 3) | Shunt current output | Sinks regulated current into optocoupler LED or pass transistor base; determines loop gain and stability |
Key Features
| Feature | Design Value |
|---|---|
| Adjustable output range | 2.5 V to 36 V via two external resistors - eliminates need for multiple fixed-voltage references |
| Low temperature drift | 14–34 mV over −40°C to +125°C - maintains regulation accuracy without external compensation |
| Sharp turn-on characteristic | Sub-100 ns response to reference threshold crossing - enables fast transient recovery in switching regulators |
| Low output noise | <10 µVRMS (0.1–10 Hz) - preserves signal integrity in precision analog feedback paths |
| High sink current | 100 mA max cathode current - directly drives standard optocouplers (e.g., PC817, SFH615A) without buffer stages |
Applications
| Industrial AC/DC Power Supply | Rack Server Power Module |
|---|---|
Use Scenario: Secondary-side voltage regulation in 300–1000 W telecom rectifiers with optocoupler-isolated feedback. IC Role / Device Role / Timing Role: Precision shunt reference setting feedback threshold for PWM controller via optocoupler current transfer ratio (CTR). Use Value: ±0.5% reference accuracy enables <±1% output voltage tolerance across line/load/temperature, meeting IEC 62368-1 requirements. |
Use Scenario: Output voltage trimming and margining in hot-swappable 12 V/54 A server PSUs with digital PMBus interface. IC Role / Device Role / Timing Role: Analog reference for DAC-controlled feedback network; provides stable baseline for fine-grained voltage adjustment. Use Value: Low 2–4 µA reference input current minimizes DAC loading error and improves resolution of 10-bit margining commands. |
| AC Inverter Drive Control | Servo Drive Feedback Loop |
Use Scenario: Isolated auxiliary supply regulation for gate drivers and current-sense amplifiers in 3-phase 7.5 kW inverters. IC Role / Device Role / Timing Role: Shunt regulator establishing stable 5 V/15 V rails for isolated logic and analog circuitry on motor control PCBs. Use Value: Q-temp rating (−40°C to +125°C) ensures reliable operation in sealed enclosures with ambient temperatures up to 85°C. |
Use Scenario: Reference source for resolver-to-digital converter (RDC) excitation and analog front-end biasing in high-bandwidth servo drives. IC Role / Device Role / Timing Role: Low-noise voltage reference for precision ADCs measuring motor phase currents and position feedback signals. Use Value: ≤10 µVRMS integrated noise (0.1–10 Hz) prevents quantization errors in 16-bit current measurement chains. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar shunt reference applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TL431BIDBZR | SOT-23-3 package; same B-grade accuracy and Q-temp range but higher RθJA (206°C/W vs 52°C/W) | Limited to lower-power applications (<300 mW) due to thermal constraints; unsuitable for >50 mA continuous cathode loads | Select when board space is critical and thermal budget permits derating; verify stability with CL ≥ 1 nF per Figure 6-18 |
| MAX6008BAUT+T | Fixed 2.5 V output; ±0.2% initial accuracy; 30 ppm/°C tempco; SOT-23-3; 10 µA max quiescent current | No adjustable output; optimized for ultra-low-power sensor biasing, not power supply feedback | Choose only for fixed-voltage, low-current (<1 mA) applications where absolute accuracy outweighs adjustability |
Compared with TL431BQPK, TL431BIDBZR offers identical electrical specs in a smaller footprint but requires thermal derating above 30 mA, while MAX6008BAUT+T trades adjustability for superior initial accuracy and lower quiescent current-making it suitable only for non-power-supply roles.
Availability
TL431BQPK is available at Aetrix Electronics and suitable for industrial AC/DC power supplies, rack server power modules, and AC inverter drive control requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for TL431BQPK 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 specializing in analog, embedded processing, and power management ICs, with decades of expertise in precision reference design and automotive-qualified components.
The TL431 product line delivers cost-effective, high-accuracy shunt references for feedback control in switching power supplies, battery chargers, and industrial power systems-designed for reliability across commercial, industrial, and automotive environments.
FAQ
What is the maximum cathode voltage rating for TL431BQPK?
The TL431BQPK has an absolute maximum cathode-to-anode voltage (VK A) of 37 V. Operation up to 36 V is supported under recommended conditions. Exceeding 37 V risks permanent damage. This rating enables use in 24 V and 36 V industrial bus systems with sufficient headroom for transient spikes.
How does TL431BQPK achieve its 0.5% reference voltage tolerance?
The TL431BQPK achieves ±0.5% initial tolerance at 25°C through laser-trimmed thin-film resistors in the internal bandgap reference circuit. This trimming occurs during final test and is validated per TI's SLVS543S specification. The tolerance remains stable over temperature due to matched thermal coefficients in the core architecture.
Can TL431BQPK replace a Zener diode in existing designs?
Yes, TL431BQPK can directly replace Zener diodes in most shunt-regulator applications. Its active error amplifier provides sharper knee characteristics, lower dynamic impedance (0.2 Ω vs typical Zener's 5–20 Ω), and adjustable output. No PCB changes are needed if pinout matches (REF–ANODE–CATHODE), but feedback resistor values must be recalculated for desired VOUT.
What is the minimum cathode current required for regulation in TL431BQPK?
The TL431BQPK requires a minimum cathode current (Imin) of 0.4 mA to maintain regulation, per Section 6.13 of the datasheet. Below this, the device exits regulation and VREF becomes undefined. Designers must ensure the feedback network and optocoupler CTR sustain ≥0.5 mA under all operating conditions, including light-load and startup.
Is TL431BQPK suitable for automotive applications?
Yes, TL431BQPK is AEC-Q100 Grade 1 qualified (−40°C to +125°C) and explicitly designated as a Q-temp device. It meets automotive requirements for under-hood power supplies, battery management system references, and ADAS subsystem biasing-provided layout follows TI's recommendations for thermal pad soldering and noise filtering.
TL431BQPK Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Package/Case:
- TO-243AA
- 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:
- 700 µA
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-89-3
TL431BQPK FAQ
1.How can I place an order for TL431BQPK through Aetrix?
Please submit a Request for Quotation (RFQ) for TL431BQPK 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 TL431BQPK reliable?
The price and inventory of TL431BQPK are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for TL431BQPK is usually 5 days.
3.What payment methods are accepted for TL431BQPK?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for TL431BQPK transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for TL431BQPK?
TL431BQPK orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your TL431BQPK 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 TL431BQPK?
For technical support, including TL431BQPK datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your TL431BQPK requirements.
6.How does Aetrix verify that TL431BQPK is sourced from the original manufacturer or authorized distributors?
All TL431BQPK 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 TL431BQPK meets industry standards.
7.What is the process for return or replacement of TL431BQPK?
All TL431BQPK units undergo pre-shipment inspection (PSI). If there is an issue with TL431BQPK, 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 TL431BQPK part is unused and in its original packaging.
Return procedure for TL431BQPK:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
TL431BQPK Tags
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TL431AIDBZR
Texas Instruments
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TL431BQDBZR
Texas Instruments
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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
Diodes Incorporated
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LM4040D20IDBZR
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LM4041DIM3-ADJ/NOPB
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LM4040DIM3X-2.5/NOPB
Texas Instruments
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LM4040DIM3-2.5/NOPB
Texas Instruments
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AZ431LANTR-G1
Diodes Incorporated
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