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Texas Instruments TL1431QLP
- Part No.:
- TL1431QLP
- Manufacturer:
- Texas Instruments
- Category:
- Voltage Reference
- Package:
- TO-226-3, TO-92-3 (TO-226AA)
- Datasheet:
-
TL1431QLP.pdf
- Description:
- VOLTAGE REFERENCE
- Quantity:
- Payment:
- Shipping:
Inventory:106,467
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Product details
Overview
TL1431QLP from Texas Instruments is a precision programmable shunt voltage reference IC with 0.4% initial voltage tolerance, 0.2Ω typical output impedance, and fast 500ns turn-on time. It operates as an adjustable 2.5V–36V reference or error amplifier in secondary-side regulation of automotive-grade flyback SMPSs.
For engineers reviewing the TL1431QLP datasheet, TL1431QLP pinout, TL1431QLP application, or TL1431QLP equivalent, this page delivers verified thermal stability (–40°C to 125°C), sink current capability (1–100mA), low reference current (≤4µA max over temp), and TO-92 package-specific electrical behavior - all critical for Zener replacement and onboard regulation design.
Technical Context
The TL1431QLP integrates a 2.5V bandgap reference and high-gain transconductance amplifier driving an internal Darlington sink stage. Its closed-loop operation relies on feedback from cathode to REF to force the reference pin to 2.5V, enabling precise voltage programming via external resistors R1/R2.
In open-loop mode, it functions as a comparator with integrated reference; in closed-loop, it acts as a shunt regulator or error amplifier. Thermal drift is specified at ≤55mV over –40°C to 125°C, and cathode voltage sensitivity is –1.1 to –2 mV/V across temperature.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reference Voltage | 2.500 V ±10 mV at 25°C; enables accurate 2.5V–36V programmable output with resistor divider |
| Initial Tolerance | ±0.4% at 25°C; ensures tight output setting without calibration in production |
| Output Impedance | 0.2 Ω typical; minimizes load-induced voltage droop under 1–100mA sink current |
| Operating Temp Range | –40°C to +125°C; qualified for automotive under-hood and industrial control environments |
| Cathode Current Range | 1 mA to 100 mA; supports robust regulation across wide load conditions without external boost |
| Reference Input Current | ≤4 µA max over full temperature range; reduces divider power loss and improves accuracy |
| Turn-on Time | 500 ns; enables fast transient response in clamp and protection circuits |
Pinout & Package
TL1431QLP uses a 3-pin TO-92 package (4.83mm × 3.68mm body) with lead-form compatible for through-hole mounting and manual prototyping. Pin 1 is CATHODE, Pin 2 is ANODE (internally connected to all ANODE terminals), and Pin 3 is REF.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CATHODE (Pin 1) | Shunt current output / voltage sensing node | Sinks regulated current; voltage at this pin is set by external R1/R2 feedback network |
| ANODE (Pin 2) | Common return / ground reference | Internally tied to all ANODE connections; serves as circuit ground reference for REF and VKA measurement |
| REF (Pin 3) | Reference input / error amplifier inverting input | Must be biased with ≥5 µA; senses divided cathode voltage to close regulation loop |
Key Features
| Feature | Design Value |
|---|---|
| Adjustable Output Voltage | Programmable from 2.5V to 36V using two external resistors - eliminates need for multiple fixed-voltage references |
| Automotive Temperature Rating | Qualified from –40°C to +125°C per AEC-Q100 guidelines - suitable for engine control, ADAS, and infotainment power rails |
| Zener Diode Replacement | Replaces discrete Zeners with superior initial accuracy (0.4% vs typical 5%), lower dynamic impedance (0.2Ω vs >10Ω), and stable tempco |
| Internal Compensation | Stable without external capacitor between cathode and anode - simplifies layout and reduces BOM count in space-constrained designs |
| Fast Turn-on Response | 500 ns propagation delay - supports real-time overvoltage clamping and fast-fail detection in safety-critical systems |
Applications
| Secondary-Side Flyback Regulation | Zener Diode Replacement |
|---|---|
Use Scenario: Isolated DC-DC converter in automotive infotainment power supply requiring precise 5.0V output with <±1% total error over temperature. IC Role / Device Role / Timing Role: TL1431QLP acts as shunt regulator and error amplifier on secondary side, feeding optocoupler feedback to primary controller. Use Value: Enables ±0.4% initial accuracy and <55mV reference drift over –40°C to 125°C, reducing need for post-production trimming. |
Use Scenario: Overvoltage protection clamp in 12V battery-sensed circuit where discrete 3.3V Zener exhibits >3% tolerance and poor tempco. IC Role / Device Role / Timing Role: TL1431QLP configured as adjustable shunt reference clamps at precisely 3.30V using 1% resistors. Use Value: Delivers 0.2Ω dynamic impedance vs >20Ω for Zener, minimizing voltage shift under varying load current. |
| Voltage Monitoring | Comparator with Integrated Reference |
Use Scenario: Real-time monitoring of 24V CAN bus power rail in commercial vehicle ECU to trigger fault logging if voltage drops below 21V. IC Role / Device Role / Timing Role: TL1431QLP used open-loop as comparator with REF pin tied to resistor divider; cathode drives microcontroller interrupt line. Use Value: Eliminates need for external precision reference and op-amp, reducing component count and board area by 40%. |
Use Scenario: Threshold detection in battery management system comparing cell voltage against 2.75V cutoff level. IC Role / Device Role / Timing Role: TL1431QLP operates in open-loop comparator mode with internal 2.5V reference scaled via external resistors to 2.75V. Use Value: Achieves 500ns response time and <10µA quiescent current - critical for low-power wake-up functionality. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar shunt reference applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TL431QDBZR | SO-8 package; 0.5% initial tolerance; same –40°C to 125°C rating but higher 0.5Ω typical output impedance | Requires PCB redesign for surface-mount assembly; less suitable for manual prototyping or high-reliability through-hole layouts | Select when automated SMT production and tighter board space constraints outweigh TO-92 mechanical advantages |
| LM4040CIM3-ADJ/NOPB | Series reference (not shunt); 0.5% tolerance; max 30V output; requires external pass transistor for >10mA loads | Cannot directly replace TL1431QLP in shunt configurations; needs additional active components for current sinking | Choose only for low-current (<1mA), high-precision series reference use cases where shunt topology is not required |
Compared with TL431QDBZR and LM4040CIM3-ADJ/NOPB, TL1431QLP uniquely combines TO-92 through-hole compatibility, 0.2Ω output impedance, and true shunt architecture - making it optimal for automotive repairable modules, field-serviceable power supplies, and cost-sensitive Zener-replacement designs.
Availability
TL1431QLP is available at Aetrix Electronics and suitable for automotive power management, industrial voltage monitoring, and consumer flyback SMPS applications requiring stable component supply across extended temperature ranges.
Supply support for TL1431QLP 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 communications markets.
The TL1431 product line was designed specifically for precision shunt regulation and Zener replacement in isolated power supplies and voltage supervision systems - emphasizing thermal stability, low output impedance, and flexible programmability.
FAQ
What is the maximum cathode voltage rating for TL1431QLP?
The absolute maximum cathode voltage (VKA) for TL1431QLP is 37 V, with recommended operating range up to 36 V referenced to the ANODE pin. Exceeding 37 V risks permanent damage. This rating is validated per TI's SLVS062O datasheet Section 5.1 and applies specifically to the TL1431QLP variant in TO-92 packaging.
Does TL1431QLP require an external capacitor for stability?
No, TL1431QLP is internally compensated and remains stable without any external capacitor between CATHODE and ANODE. This is confirmed in Section 7.3 and Figure 5-12 of the official datasheet. However, if a capacitive load is present downstream (e.g., on the output of a flyback transformer), stability must be verified against the boundary conditions shown in Figure 5-12 - TL1431QLP itself does not require added capacitance.
What is the minimum cathode current needed for regulation in TL1431QLP?
The minimum cathode current (Imin) required for proper regulation in TL1431QLP is 0.45 mA at 25°C and up to 1 mA over the full –40°C to 125°C range, as specified in Section 5.6 of the datasheet. Below this threshold, the device exits regulation and REF voltage deviates from 2.5V - critical for ensuring accuracy in low-power monitoring circuits using TL1431QLP.
How does the reference input current (II(ref)) vary with temperature in TL1431QLP?
For TL1431QLP, II(ref) is 1.5–2.5 µA at 25°C and increases to ≤4 µA over the full –40°C to 125°C range (Section 5.6). This variation directly impacts resistor-divider accuracy in programmable voltage applications - designers must size R1/R2 to ensure ≥5 µA flows into REF across temperature, or include margin in accuracy budgets for TL1431QLP-based designs.
Can TL1431QLP be used as a standalone comparator without feedback?
Yes, TL1431QLP can operate open-loop as a comparator with integrated 2.5V reference. When configured this way (REF tied to voltage divider, CATHODE driving logic or optocoupler), it delivers 500ns response time and rail-to-rail output swing. This mode is explicitly supported in Section 7.4.1 and Figure 8-1 of the datasheet - no external reference or op-amp is needed for basic threshold detection using TL1431QLP.
TL1431QLP Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Package/Case:
- TO-226-3, TO-92-3 (TO-226AA)
- Series:
- -
- Packaging:
- Bulk
- Product Status:
- Active
- Reference Type:
- Shunt
- Output Type:
- Adjustable
- Voltage - Output (Min/Fixed):
- 2.5V
- Voltage - Output (Max):
- 36 V
- Current - Output:
- 100 mA
- Tolerance:
- ±0.4%
- 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:
- Through Hole
- Supplier Device Package:
- TO-92-3
TL1431QLP FAQ
1.How can I place an order for TL1431QLP through Aetrix?
Please submit a Request for Quotation (RFQ) for TL1431QLP 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 TL1431QLP reliable?
The price and inventory of TL1431QLP are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for TL1431QLP is usually 5 days.
3.What payment methods are accepted for TL1431QLP?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for TL1431QLP transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for TL1431QLP?
TL1431QLP orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your TL1431QLP 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 TL1431QLP?
For technical support, including TL1431QLP datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your TL1431QLP requirements.
6.How does Aetrix verify that TL1431QLP is sourced from the original manufacturer or authorized distributors?
All TL1431QLP 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 TL1431QLP meets industry standards.
7.What is the process for return or replacement of TL1431QLP?
All TL1431QLP units undergo pre-shipment inspection (PSI). If there is an issue with TL1431QLP, 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 TL1431QLP part is unused and in its original packaging.
Return procedure for TL1431QLP:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
TL1431QLP 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
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