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Texas Instruments TL431IPK3
- Part No.:
- TL431IPK3
- Manufacturer:
- Texas Instruments
- Category:
- Voltage Reference
- Package:
- TO-243AA
- Datasheet:
-
TL431IPK3.pdf
- Description:
- IC VREF SHUNT ADJ 2% SOT89-3
- Quantity:
- Payment:
- Shipping:
Inventory:3,629
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Product details
Overview
TL431IPK3 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 (B grade), 14 mV max temperature drift over −40°C to 125°C, 0.2 Ω typical dynamic impedance, and 1–100 mA sink-current capability. It serves as a stable feedback element in isolated DC-DC converters and AC/DC power supplies.
For engineers reviewing the TL431IPK3 datasheet, TL431IPK3 pinout, TL431IPK3 application, or TL431IPK3 equivalent, key selection factors include its Q-grade automotive temperature range, SOT-89 thermal performance (RθJA = 52°C/W), low-noise operation, and compatibility with adjustable output regulation from 2.5 V to 36 V using two external resistors.
Technical Context
The TL431IPK3 implements an internal bandgap reference, error amplifier, and NPN output transistor in a three-terminal shunt topology. Its REF pin senses voltage relative to ANODE, triggering cathode current modulation to maintain precise regulation at the setpoint defined by external resistor dividers.
It operates across −40°C to +125°C (Q-grade), supports cathode voltages up to 36 V, and maintains stability with load capacitance up to 1 µF-critical for flyback and forward converter feedback loops where phase margin and transient response are design-critical.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reference Voltage | 2.495 V ±12.5 mV (B grade, 25°C); enables accurate 5 V, 12 V, or 24 V output setting in regulated supplies |
| Initial Tolerance | ±0.5% at 25°C; reduces need for post-production trimming in high-volume power modules |
| Temp Drift (VI(dev)) | ≤14 mV over −40°C to 125°C; ensures ≤0.56% output variation across full automotive operating range |
| Dynamic Impedance | 0.2 Ω typical; minimizes output voltage perturbation under fast load transients in SMPS feedback paths |
| Sink Current Range | 1 mA to 100 mA; supports direct optocoupler LED drive without external buffer in isolated topologies |
| Cathode Voltage Max | 36 V; allows use in 24 V industrial bus and 32 V telecom systems without series dropping resistor |
| Output Noise | Low broadband noise (<10 µVRMS over 10 Hz–10 kHz); preserves loop stability in high-gain compensation networks |
Pinout & Package
SOT-89 package (3-pin, 4.5 mm × 2.5 mm × 1.5 mm body), thermally enhanced with exposed tab connected to ANODE for PCB heat sinking.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| REF | Reference input | Senses divided output voltage; must be biased ≥2.5 V above ANODE to activate regulation |
| ANODE | Common return path | Connected to system ground or negative rail; also serves as thermal pad attachment point |
| CATHODE | Shunt current output | Sinks current into feedback network; drives optocoupler LED or error amplifier input directly |
Key Features
| Feature | Design Value |
|---|---|
| Adjustable output range | 2.5 V to 36 V via two-resistor divider-enables single BOM for multiple output voltages |
| Sharp turn-on characteristic | Fast regulation onset below Vref threshold-reduces startup delay and improves light-load efficiency |
| Low output impedance | 0.2 Ω typical-maintains tight regulation despite varying optocoupler CTR degradation over life |
| High temp grade support | −40°C to +125°C operation-qualified for under-hood automotive and industrial motor drive applications |
| ESD robustness | ±2000 V HBM-survives handling and board assembly without special ESD controls |
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 data center PSUs. IC Role / Device Role / Timing Role: Shunt reference providing feedback to optocoupler in primary-side controller loop. Use Value: ±0.5% tolerance and 14 mV drift ensure <±1% output accuracy across full thermal and load range-meeting 80 PLUS Titanium requirements. | Use Scenario: Output voltage regulation in 3-phase 400 VAC rectified, 24 V/20 A industrial power supply. IC Role / Device Role / Timing Role: Precision shunt reference in TL431-based linear post-regulator stage after bulk switching converter. Use Value: 0.2 Ω dynamic impedance suppresses ripple coupling into feedback node, enabling <10 mVpp output ripple without additional filtering. |
| AC Inverter & VF Drives | Servo Drive Control Module |
Use Scenario: DC bus voltage monitoring and protection reference in 690 VAC variable-frequency drives. IC Role / Device Role / Timing Role: High-voltage shunt reference feeding comparator input for overvoltage lockout circuitry. Use Value: 36 V cathode rating allows direct connection to scaled-down DC bus (e.g., 1:100 resistive divider), eliminating level-shifting amplifiers. | Use Scenario: Isolated feedback for ±15 V analog control rails powering gate drivers and position encoder interfaces. IC Role / Device Role / Timing Role: Dual-rail reference generator using two TL431IPK3 units-one per polarity-with shared ANODE ground. Use Value: Matched 2.495 V references ensure symmetrical rail tracking (ΔVout < 5 mV), critical for minimizing common-mode distortion in servo amplifiers. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar shunt reference applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TL431CDBZR | SOT-23-3 package, C-grade (0°C–70°C), same 0.5% tolerance but higher RθJA (206°C/W) | Limited to commercial-temperature environments; unsuitable for under-hood or enclosed industrial enclosures | Select when cost and board space are prioritized over thermal performance and extended temperature range |
| LM4040CIM3-ADJ | Series reference (not shunt), fixed 2.5 V output, ±0.5% tolerance, 75 ppm/°C drift, 100 µA max quiescent current | Requires external pass transistor for >10 mA loads; cannot directly replace shunt topology without circuit redesign | Choose only for low-power, non-isolated applications where sink-current capability is unnecessary |
Compared with TL431CDBZR and LM4040CIM3-ADJ, the TL431IPK3 uniquely combines Q-grade temperature range, SOT-89 thermal efficiency, and true shunt architecture-making it the only option that preserves existing flyback feedback layout while meeting automotive and industrial reliability targets.
Availability
TL431IPK3 is available at Aetrix Electronics and suitable for rack server power, industrial AC/DC, and servo drive control module applications requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.
Supply support for TL431IPK3 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 and embedded processing technologies, with decades of leadership in precision analog ICs and power management solutions.
The TL431 product line was designed specifically for high-accuracy, high-reliability shunt regulation in isolated power conversion systems-targeting automotive, industrial, and computing markets demanding long-term parametric stability.
FAQ
What is the maximum cathode voltage rating for TL431IPK3?
The TL431IPK3 has an absolute maximum cathode voltage (VK A) of 37 V, with recommended operation up to 36 V. This allows direct use in 24 V and 32 V industrial bus systems and supports resistive scaling from higher DC bus voltages (e.g., 400 VDC) without external clamping. Exceeding 36 V risks exceeding power dissipation limits and degrading long-term reliability.
How does TL431IPK3 differ from standard TL431 variants like TL431CDR?
The TL431IPK3 is the Q-grade (−40°C to +125°C) version in SOT-89 package with 0.5% initial tolerance (B grade), whereas TL431CDR is C-grade (0°C to 70°C) in SOIC-8. The TL431IPK3's lower thermal resistance (52°C/W vs. 97°C/W) and extended temperature range make it suitable for under-hood automotive and high-ambient industrial applications where the C-grade part would derate prematurely.
Can TL431IPK3 replace a Zener diode in existing designs?
Yes, the TL431IPK3 can directly replace Zener diodes in most shunt regulator applications due to its sharp turn-on characteristic, lower dynamic impedance (0.2 Ω vs. typical 5–20 Ω for Zeners), and tighter voltage tolerance. However, the three-terminal configuration requires connecting REF to the divider node, ANODE to ground, and CATHODE to the supply rail-unlike two-terminal Zener placement.
What is the minimum cathode current required for regulation in TL431IPK3?
The TL431IPK3 requires a minimum cathode current (Imin) of 0.4 mA to maintain regulation, with typical value of 0.7 mA across −40°C to +125°C. This ensures reliable startup and feedback loop operation even with high-value resistor dividers or low-CTR optocouplers, unlike many Zener diodes that require ≥5 mA for stable voltage.
Does TL431IPK3 support adjustable output voltage, and what is the range?
Yes, the TL431IPK3 supports fully adjustable output voltage from 2.5 V to 36 V using two external resistors forming a voltage divider from output to REF pin. The formula is VOUT = Vref × (1 + R1/R2), where Vref = 2.495 V. This flexibility enables single-design reuse across multiple output rails without changing the IC.
TL431IPK3 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:
- ±2%
- Temperature Coefficient:
- -
- Noise - 0.1Hz to 10Hz:
- -
- Noise - 10Hz to 10kHz:
- -
- Voltage - Input:
- -
- Current - Supply:
- -
- Current - Cathode:
- 1 mA
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-89-3
TL431IPK3 FAQ
1.How can I place an order for TL431IPK3 through Aetrix?
Please submit a Request for Quotation (RFQ) for TL431IPK3 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 TL431IPK3 reliable?
The price and inventory of TL431IPK3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for TL431IPK3 is usually 5 days.
3.What payment methods are accepted for TL431IPK3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for TL431IPK3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for TL431IPK3?
TL431IPK3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your TL431IPK3 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 TL431IPK3?
For technical support, including TL431IPK3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your TL431IPK3 requirements.
6.How does Aetrix verify that TL431IPK3 is sourced from the original manufacturer or authorized distributors?
All TL431IPK3 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 TL431IPK3 meets industry standards.
7.What is the process for return or replacement of TL431IPK3?
All TL431IPK3 units undergo pre-shipment inspection (PSI). If there is an issue with TL431IPK3, 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 TL431IPK3 part is unused and in its original packaging.
Return procedure for TL431IPK3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
TL431IPK3 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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