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Texas Instruments TL431LIBQDBZR
- Part No.:
- TL431LIBQDBZR
- Manufacturer:
- Texas Instruments
- Category:
- Voltage Reference
- Package:
- TO-236-3, SC-59, SOT-23-3
- Datasheet:
-
TL431LIBQDBZR.pdf
- Description:
- IC VREF SHUNT ADJ 0.5% SOT23-3
- Quantity:
- Payment:
- Shipping:
Inventory:7,364
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Product details
Overview
TL431LIBQDBZR from Texas Instruments is a three-terminal adjustable shunt regulator with 0.5% reference voltage tolerance at 25°C, 2.495 V nominal Vref, and operation across −40°C to +125°C (Q-temp grade). It delivers 15 mA sink current, 0.3 Ω dynamic impedance, and 0.4 µA max reference input current - enabling precision secondary-side regulation in automotive flyback SMPS.
For engineers reviewing the TL431LIBQDBZR datasheet, TL431LIBQDBZR pinout, TL431LIBQDBZR application, or TL431LIBQDBZR equivalent, key selection considerations include its Q-temp automotive qualification, optimized IREF/II(dev) for low-leakage designs, SOT-23 (DBZ) package compatibility, and functional equivalence to TL431 with improved thermal stability over temperature.
Technical Context
The TL431LIBQDBZR integrates an accurate 2.495 V bandgap reference and high-gain op-amp in a single silicon die, configured as a programmable shunt regulator. Its Darlington output stage enables 15 mA cathode sink capability while maintaining 0.3 Ω typical dynamic impedance across 1–15 mA cathode current range.
It operates in two primary modes: open-loop comparator (with integrated reference) and closed-loop shunt regulation. In closed loop, feedback from cathode to REF sets output voltage from Vref to 36 V using two external resistors; minimum cathode current of 1 mA is required to maintain regulation and sufficient gain.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Vref Tolerance @ 25°C | ±0.5% (B grade) - ensures initial accuracy of 2.483–2.507 V for high-precision voltage setting |
| Operating Temperature Range | −40°C to +125°C (Q grade) - qualified for under-hood automotive and industrial environments |
| Dynamic Impedance |ZKA| | 0.3 Ω typical - minimizes output voltage variation under load transients in regulation circuits |
| IREF Max | 0.4 µA - enables high-impedance resistor networks without significant reference current error |
| IKA Range | 1 mA to 15 mA - defines stable regulation window; below 1 mA, gain drops and regulation degrades |
| VI(dev) Max (Q Temp) | 27 mV - total reference voltage drift over full temperature range, critical for wide-temp stability |
| Package | SOT-23 (DBZ), 2.90 mm × 1.30 mm - surface-mount compatible with standard pick-and-place and reflow processes |
Pinout & Package
SOT-23 (DBZ) package: 3-pin, 2.90 mm × 1.30 mm body, gull-wing leads, JEDEC MO-178AC compliant.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CATHODE (Pin 1) | Shunt current output / voltage sensing node | Carries regulated sink current; voltage at this pin is set by REF-to-ANODE feedback network; must be ≥ Vref to activate regulation |
| REF (Pin 2) | Reference input / threshold sense | Compares external voltage to internal 2.495 V reference; requires ≤0.4 µA input current; must not float - needs defined DC path to ANODE |
| ANODE (Pin 3) | Common return / ground reference | Acts as circuit common; all voltages referenced to this pin; connected directly to system ground or lowest potential node in shunt configuration |
Key Features
| Feature | Design Value |
|---|---|
| Optimized reference input current | IREF ≤ 0.4 µA (max) - reduces resistor-divider error and enables high-value feedback networks for low-power biasing |
| Low temperature drift | VI(dev) = 27 mV over −40°C to +125°C - supports stable voltage references in automotive engine control units |
| Sharp turn-on characteristic | High open-loop gain + Darlington output - provides fast, clean switching in comparator mode with minimal hysteresis |
| Internal compensation | Stable without output capacitor - eliminates need for external stabilization components in most shunt regulator configurations |
| Pin-to-pin replacement for TL431 | Same DBZ footprint and function as legacy TL431 - allows drop-in upgrade with improved IREF and II(dev) performance |
Applications
| Secondary-Side Regulation in Flyback SMPS | Zener Diode Replacement |
|---|---|
Use Scenario: Isolated DC-DC converter where TL431LIBQDBZR senses output voltage via optocoupler feedback to regulate primary-side controller. IC Role / Device Role / Timing Role: Precision shunt regulator providing error signal to optocoupler LED; replaces discrete Zener + transistor in feedback loop. Use Value: 0.5% Vref tolerance and 27 mV VI(dev) ensure ±1.5% total output regulation over temperature and line, meeting automotive ASIL-B requirements. | Use Scenario: On-board 3.3 V or 5 V rail stabilization where space-constrained design demands compact, accurate voltage clamping. IC Role / Device Role / Timing Role: Adjustable shunt reference replacing fixed-voltage Zener diodes; configured with two resistors for exact voltage setpoint. Use Value: 0.3 Ω dynamic impedance yields <10 mV droop at 10 mA load shift - outperforming 5% tolerance Zeners with >10 Ω impedance. |
| Voltage Monitoring / Threshold Detection | Precision Constant Current Sink |
Use Scenario: Battery pack voltage supervision in EV charging modules detecting overvoltage or undervoltage conditions. IC Role / Device Role / Timing Role: Comparator with integrated 2.495 V reference; REF pin biased by resistive divider from monitored rail. Use Value: 0.4 µA max IREF enables high-impedance sensing (e.g., 1 MΩ divider) with <0.4 V error - preserving battery runtime and measurement fidelity. | Use Scenario: LED driver or sensor bias circuit requiring stable 10–100 mA current independent of supply variation. IC Role / Device Role / Timing Role: Error amplifier controlling external pass transistor (BJT/MOSFET) to force current through sense resistor RS. Use Value: 2.495 V reference with 0.5% tolerance sets current accuracy to ±0.5% (plus RS tolerance), enabling <1% total sink error in production systems. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar shunt regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TL431CDBZR | 1% Vref tolerance (A grade), C-temp range (0°C to 70°C), same SOT-23 package | Not qualified for automotive or extended industrial use; lower accuracy limits tight-regulation designs | Select when cost sensitivity outweighs accuracy/temp requirements; verify ambient operating range stays within 0–70°C |
| TL432LIBQDBZR | Identical electrical specs and Q-temp rating, but reversed REF/CATHODE pinout in DBZ package | Requires PCB layout revision; incompatible with TL431LIBQDBZR footprint without trace modification | Choose only if redesign accommodates pin swap; otherwise TL431LIBQDBZR maintains direct board compatibility |
Compared with TL431CDBZR, TL431LIBQDBZR offers tighter initial accuracy and extended temperature range for mission-critical regulation; compared with TL432LIBQDBZR, it retains legacy TL431 pinout for seamless replacement without layout changes.
Availability
TL431LIBQDBZR is available at Aetrix Electronics and suitable for automotive power conversion, industrial voltage monitoring, and precision current sink applications requiring stable component supply across extended temperature ranges.
Supply support for TL431LIBQDBZR 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 delivering analog and embedded processing solutions for industrial, automotive, and personal electronics markets.
The TL43xLI product line was designed specifically for high-accuracy, temperature-stable shunt regulation and reference applications - targeting automotive secondary-side SMPS, precision instrumentation, and safety-critical voltage supervision.
FAQ
What is the maximum cathode voltage rating for TL431LIBQDBZR?
The absolute maximum cathode-to-anode voltage (VKA) for TL431LIBQDBZR is 37 V, with recommended operating range from Vref (2.495 V) up to 36 V. Exceeding 37 V risks permanent damage. This rating enables use in 24 V and 36 V automotive and industrial bus systems while maintaining margin for transients.
Does TL431LIBQDBZR require an external capacitor for stability?
No, TL431LIBQDBZR is internally compensated and remains stable without an output capacitor between CATHODE and ANODE under typical resistive feedback conditions. However, if a capacitive load (e.g., >2 µF) is used, consult Figure 12 in the datasheet to select appropriate series resistance or capacitance values to avoid oscillation.
How does the Q-temp grade affect TL431LIBQDBZR's performance in automotive applications?
The Q-temp grade certifies TL431LIBQDBZR for continuous operation from −40°C to +125°C, with guaranteed VI(dev) ≤ 27 mV and IREF ≤ 0.4 µA across that full range. This ensures reliable voltage reference accuracy in under-hood ECUs, battery management systems, and ADAS power supplies where ambient temperatures exceed commercial-grade limits.
Can TL431LIBQDBZR be used as a comparator, and what are the key design constraints?
Yes, TL431LIBQDBZR functions as a comparator with integrated 2.495 V reference in open-loop mode. Key constraints: cathode current must exceed 1 mA for sufficient gain; REF pin requires ≥10% overdrive above Vref for fast response; output is open-collector, so pull-up to VSUP is mandatory; output low level is ~2 V, requiring level-shifting for 1.8 V/3.3 V logic interfaces.
What is the minimum cathode current needed for TL431LIBQDBZR to regulate properly?
TL431LIBQDBZR requires a minimum cathode current (IKA) of 1 mA to enter and sustain regulation. Below this threshold, open-loop gain drops significantly, causing sluggish response, poor line/load regulation, and potential failure to maintain setpoint. Designers must ensure bias networks deliver ≥1 mA even under worst-case (e.g., min VIN, max R1+R2) conditions.
TL431LIBQDBZR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Package/Case:
- TO-236-3, SC-59, SOT-23-3
- 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:
- 15 mA
- Tolerance:
- ±0.5%
- Temperature Coefficient:
- -
- Noise - 0.1Hz to 10Hz:
- -
- Noise - 10Hz to 10kHz:
- -
- Voltage - Input:
- -
- Current - Supply:
- -
- Current - Cathode:
- 1 mA
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-23-3
TL431LIBQDBZR FAQ
1.How can I place an order for TL431LIBQDBZR through Aetrix?
Please submit a Request for Quotation (RFQ) for TL431LIBQDBZR 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 TL431LIBQDBZR reliable?
The price and inventory of TL431LIBQDBZR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for TL431LIBQDBZR is usually 5 days.
3.What payment methods are accepted for TL431LIBQDBZR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for TL431LIBQDBZR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for TL431LIBQDBZR?
TL431LIBQDBZR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your TL431LIBQDBZR 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 TL431LIBQDBZR?
For technical support, including TL431LIBQDBZR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your TL431LIBQDBZR requirements.
6.How does Aetrix verify that TL431LIBQDBZR is sourced from the original manufacturer or authorized distributors?
All TL431LIBQDBZR 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 TL431LIBQDBZR meets industry standards.
7.What is the process for return or replacement of TL431LIBQDBZR?
All TL431LIBQDBZR units undergo pre-shipment inspection (PSI). If there is an issue with TL431LIBQDBZR, 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 TL431LIBQDBZR part is unused and in its original packaging.
Return procedure for TL431LIBQDBZR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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