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Texas Instruments TL431BQDR
- Part No.:
- TL431BQDR
- Manufacturer:
- Texas Instruments
- Category:
- Voltage Reference
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
TL431BQDR.pdf
- Description:
- IC VREF SHUNT ADJ 0.5% 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,391
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Product details
Overview
TL431BQDR from Texas Instruments is a precision programmable shunt voltage reference IC with 0.5% initial tolerance at 25°C, adjustable output from 2.483 V to 36 V, and operation across −40°C to +125°C for automotive-qualified applications. It delivers 0.2 Ω typical dynamic impedance, 1–100 mA sink-current capability, and low 14–34 mV total reference voltage drift over temperature - used in feedback loops of isolated DC/DC converters and industrial power supplies.
For engineers reviewing the TL431BQDR datasheet, TL431BQDR pinout, TL431BQDR application, or TL431BQDR equivalent, this page provides verified electrical specs, SOT-23-3 terminal mapping, thermal performance data, and validated alternatives for high-reliability power regulation design.
Technical Context
The TL431BQDR implements a three-terminal adjustable shunt regulator architecture with an internal 2.495 V reference amplifier, error comparator, and NPN pass transistor. Its sharp turn-on characteristic and active output stage enable Zener diode replacement in closed-loop feedback paths where precise voltage thresholding and stable current sinking are required.
It operates as a two-input (REF, ANODE), one-output (CATHODE) device: REF senses external resistor divider voltage; when that voltage exceeds Vref, the cathode sinks current to maintain regulation. The Q-grade rating confirms −40°C to +125°C operation with B-grade (0.5%) accuracy and 14–34 mV total Vref deviation over full temperature range.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reference Voltage | 2.483–2.507 V at 25°C (0.5% B-grade tolerance); sets minimum regulated output in resistor-divider configurations |
| Temp Range | −40°C to +125°C (Q-grade); supports under-hood automotive and industrial ambient conditions without derating |
| Vref Drift | 14–34 mV max over full temperature range; ensures <±0.014% output stability in precision feedback networks |
| Dynamic Impedance | 0.2 Ω typical (≤0.5 Ω max); maintains tight regulation under fast load transients in switching power supply compensation |
| Sink Current | 1–100 mA continuous; enables direct drive of optocoupler LEDs or secondary-side error amplifiers without buffering |
| Output Noise | Low broadband noise (typ. 200 nV/√Hz @ 1 kHz); minimizes jitter in voltage-controlled oscillator (VCO) biasing and analog sensing |
| Input Bias Current | 2–4 µA at REF pin; allows use of high-value feedback resistors (>1 MΩ) to reduce power loss in battery-powered systems |
Pinout & Package
SOT-23-3 package (2.90 mm × 1.30 mm body size), surface-mount, lead-free, RoHS-compliant. Pin 1 = CATHODE, Pin 2 = REF, Pin 3 = ANODE.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CATHODE (Pin 1) | Current-sink output node | Connects to primary-side controller feedback (e.g., UC384x COMP pin) or optocoupler anode; sinks up to 100 mA |
| REF (Pin 2) | Reference input threshold | Compares external resistor-divider voltage against internal 2.495 V bandgap; triggers regulation when ≥Vref |
| ANODE (Pin 3) | Common return path | Typically tied to system ground or negative rail; serves as reference point for both REF and CATHODE voltages |
Key Features
| Feature | Design Value |
|---|---|
| 0.5% Initial Accuracy | B-grade tolerance at 25°C enables ±12 mV absolute output setting error before trimming - critical for compliance with USB PD or telecom voltage margins |
| Automotive-Qualified Temp Range | −40°C to +125°C operation (Q-grade) meets AEC-Q100 stress test requirements for engine control and ADAS power modules |
| 0.2 Ω Dynamic Impedance | Ensures <10 mV output deviation during 50 mA step-load changes in flyback converter feedback loops |
| 1–100 mA Sink Capability | Directly drives PC817/PC817x optocouplers (IF = 5–10 mA) without external transistor - simplifies isolated feedback design |
| Low Reference Input Current | 2–4 µA REF pin current permits >1 MΩ upper feedback resistor values, reducing standby power by >90% vs. 10 kΩ designs |
Applications
| Industrial AC/DC Power Supply | Rack Server Power Module |
|---|---|
Use Scenario: Regulated 12 V/48 V output in DIN-rail mounted 300 W AC/DC converter with primary-side PWM controller. IC Role / Device Role / Timing Role: Secondary-side shunt reference providing error signal to optocoupler, closing voltage loop with <±0.5% line/load regulation. Use Value: Enables single-resistor output adjustment across 5–58 V range while maintaining 0.5% setpoint accuracy over −25°C to +70°C ambient. |
Use Scenario: Multi-phase VRM feedback in 1U server PSU delivering 12 V@120 A to CPU/GPU rails. IC Role / Device Role / Timing Role: Precision reference for digital power controller's ADC reference or analog error amplifier input. Use Value: 14–34 mV Vref drift over −40°C to +125°C ensures <±0.03% output voltage shift across full thermal envelope - meeting Intel VR13 spec. |
| AC Inverter Drive Control | Servo Drive Feedback Loop |
Use Scenario: DC bus voltage monitoring and overvoltage protection circuit in 3-phase 220 V AC inverter for HVAC compressors. IC Role / Device Role / Timing Role: High-accuracy voltage threshold detector triggering shutdown when DC link exceeds 400 V. Use Value: 0.5% tolerance and 14 mV max drift allow trip point setting at 400.0 V ±2.0 V - eliminating need for manual calibration. |
Use Scenario: Isolated current-sense amplifier reference in servo motor driver with Hall-effect feedback. IC Role / Device Role / Timing Role: Stable 2.5 V reference for delta-sigma ADC biasing and analog front-end gain staging. Use Value: Low 0.2 Ω output impedance prevents reference droop during 100 kHz PWM switching, preserving current measurement linearity. |
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, same B-grade accuracy and Q-temp rating, but TI's alternate orderable variant with identical electrical specs and pinout | No functional difference; used interchangeably in new designs where DBZR suffix is preferred in procurement | Select TL431BIDBZR only if sourcing constraints require TI's alternate part number - electrically and mechanically identical to TL431BQDR |
| AS431BZTR-G1 | 0.5% initial tolerance, −40°C to +125°C, but higher 0.5 Ω max dynamic impedance and 20–40 mV Vref drift | Acceptable for non-critical industrial supplies; not recommended for telecom or server applications requiring <±0.02% long-term stability | Choose AS431BZTR-G1 only for cost-sensitive designs where 0.3 Ω higher impedance and wider drift are acceptable trade-offs |
Compared with TL431BQDR, TL431BIDBZR offers identical performance and drop-in compatibility, while AS431BZTR-G1 trades 0.3 Ω higher dynamic impedance and broader Vref drift for lower unit cost - making TL431BQDR optimal for high-stability feedback loops.
Availability
TL431BQDR 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 multi-year production cycles.
Supply support for TL431BQDR 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 technologies, with over 50 years of innovation in precision analog ICs.
The TL431 product line was designed specifically for high-accuracy, low-drift shunt voltage regulation in isolated power supply feedback paths - targeting automotive, industrial, and computing applications demanding long-term stability and wide temperature operation.
FAQ
What is the reference voltage tolerance of TL431BQDR at 25°C?
The TL431BQDR has a 0.5% initial reference voltage tolerance at 25°C, corresponding to a guaranteed 2.483 V to 2.507 V range. This B-grade accuracy is specified in Section 6.13 of the TI SLVS543S datasheet and applies across the full −40°C to +125°C operating range with additional drift limits.
Does TL431BQDR support operation at 125°C junction temperature?
Yes, TL431BQDR is rated for operation from −40°C to +125°C ambient (Q-grade), with maximum junction temperature of 150°C. Its thermal resistance (RθJA) in SOT-23-3 is 206°C/W, so at 100 mA sink current and 5 V cathode-anode differential, power dissipation remains within safe limits even at 125°C ambient.
What is the minimum cathode current required for regulation in TL431BQDR?
The TL431BQDR requires a minimum cathode current (Imin) of 0.4 mA to maintain regulation, per Section 6.13 of the datasheet. Below this threshold, the device exits regulation mode and cathode voltage rises above the setpoint - critical for designing optocoupler bias networks with high-value resistors.
Can TL431BQDR replace a Zener diode in a 24 V power supply feedback loop?
Yes, TL431BQDR directly replaces Zener diodes in feedback loops due to its sharp turn-on, 0.2 Ω dynamic impedance, and adjustable 2.483–36 V output. Unlike Zeners, it achieves 0.5% accuracy and stable temperature coefficient - enabling tighter output regulation in 24 V industrial PSUs without trimming.
What package type is used for TL431BQDR and what are its dimensions?
TL431BQDR uses the SOT-23-3 package with nominal body size 2.90 mm × 1.30 mm. Pin 1 is CATHODE, Pin 2 is REF, and Pin 3 is ANODE - confirmed in TI's Pin Configuration and Functions section (Figure 5-1, DBZ package drawing) and Mechanical Information table.
TL431BQDR 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:
- 700 µA
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
TL431BQDR FAQ
1.How can I place an order for TL431BQDR through Aetrix?
Please submit a Request for Quotation (RFQ) for TL431BQDR 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 TL431BQDR reliable?
The price and inventory of TL431BQDR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for TL431BQDR is usually 5 days.
3.What payment methods are accepted for TL431BQDR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for TL431BQDR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for TL431BQDR?
TL431BQDR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your TL431BQDR 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 TL431BQDR?
For technical support, including TL431BQDR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your TL431BQDR requirements.
6.How does Aetrix verify that TL431BQDR is sourced from the original manufacturer or authorized distributors?
All TL431BQDR 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 TL431BQDR meets industry standards.
7.What is the process for return or replacement of TL431BQDR?
All TL431BQDR units undergo pre-shipment inspection (PSI). If there is an issue with TL431BQDR, 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 TL431BQDR part is unused and in its original packaging.
Return procedure for TL431BQDR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
TL431BQDR Tags
-
TL431AIDBZR
Texas Instruments
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TL431BQDBZR
Texas Instruments
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AN431AN-ATRG1
Diodes Incorporated
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LM4040CYM3-2.5-TR
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LM4040CYM3-4.1-TR
Microchip Technology
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LM4040EIM3-2.5/NOPB
Texas Instruments
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AZ431LBNTR-G1
Diodes Incorporated
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LM4040D20IDBZR
Texas Instruments
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LM4041DIM3-ADJ/NOPB
Texas Instruments
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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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