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Diodes Incorporated ZTL431BFFTA
- Part No.:
- ZTL431BFFTA
- Manufacturer:
- Diodes Incorporated
- Category:
- Voltage Reference
- Package:
- SOT-23-3 Flat Leads
- Datasheet:
-
ZTL431BFFTA.pdf
- Description:
- IC VREF SHUNT ADJ 0.5% SOT23F
- Quantity:
- Payment:
- Shipping:
Inventory:3,430
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Product details
Overview
ZTL431BFFTA from Diodes Incorporated is a 0.5%-tolerance adjustable precision shunt regulator in SOT23F package, providing stable 2.5 V reference voltage with ±0.013 V initial accuracy at +25°C, 0.2 Ω typical dynamic output impedance, and 1–100 mA cathode sink current capability for linear regulator feedback and opto-coupler linearization circuits.
For engineers reviewing the ZTL431BFFTA datasheet, ZTL431BFFTA pinout, ZTL431BFFTA application, or ZTL431BFFTA equivalent, this device serves as a high-accuracy, temperature-stable (−40°C to +125°C) replacement for discrete zener diodes in voltage reference, overvoltage protection, and isolated feedback loop designs requiring tight regulation and low output impedance.
Technical Context
The ZTL431BFFTA operates as a three-terminal programmable shunt regulator where the REF pin senses voltage via external resistor divider, triggering cathode current sink to maintain VREF = 2.5 V across the anode–cathode terminals. Its internal bandgap reference and error amplifier deliver 0.5% initial tolerance and <34 mV reference deviation over −40°C to +125°C.
It features 0.2 Ω typical dynamic output impedance and supports cathode voltages up to 20 V with 150 mA absolute maximum sink current. Stability is ensured with ≥4.7 nF anode–cathode capacitance, per manufacturer's boundary condition guidance.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reference Voltage (VREF) | 2.5 V nominal, ±0.013 V (0.5%) at +25°C - sets precise feedback threshold for regulator loops |
| Temp Range | −40°C to +125°C ambient - enables operation in automotive under-hood and industrial control environments |
| Cathode Current Range | 1 mA to 100 mA - supports direct feedback into optocouplers or higher-current shunt regulation |
| Dynamic Output Impedance | 0.2 Ω typical - minimizes output voltage shift under load transients in closed-loop systems |
| Max Cathode Voltage (VKA) | 20 V - allows use in 12 V and 15 V supply rails with margin for ripple and surge |
| Ref Input Current | 2 μA typical - reduces divider resistor power loss and improves high-impedance sensing accuracy |
| Output Voltage Range | 2.5 V to 20 V (via R1/R2) - enables flexible programmability without external op-amps |
Pinout & Package
SOT23F (FF-suffix) package: ultra-thin, lead-free surface-mount outline with 1.18 mm height, 2.90 mm × 2.40 mm footprint, and 0.95 mm pitch; optimized for space-constrained DC/DC feedback and isolated power supply layouts.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 (Anode) | Anode terminal | Connected to system ground or low-side return; internal substrate tie - must be left floating or tied to Anode per datasheet |
| Pin 2 (Cathode) | Cathode terminal | Sinks regulated current to maintain VREF; connects to positive rail or optocoupler LED anode |
| Pin 3 (Ref) | Reference input | Senses divided output voltage; high-impedance node (2 μA typical) enabling high-R divider networks |
Key Features
| Feature | Design Value |
|---|---|
| 0.5% reference voltage tolerance (B grade) | Enables ±0.013 V initial accuracy at +25°C - critical for high-precision feedback in telecom and industrial PSUs |
| −40°C to +125°C operating range | Guarantees stable regulation across extended industrial and automotive ambient conditions without derating |
| 0.2 Ω dynamic output impedance | Minimizes load-induced VREF drift during transient events - improves loop stability in flyback converters |
| 1–100 mA cathode sink capability | Directly drives standard optocoupler LEDs (e.g., PC817) without buffer stages in isolated SMPS designs |
| Stable with ≥4.7 nF anode–cathode capacitance | Ensures robust phase margin in feedback paths using common ceramic capacitors - simplifies layout validation |
Applications
| Opto-Coupler Linearization | Linear Regulator Feedback |
|---|---|
|
Use Scenario: Isolated feedback path in flyback or forward converters using PC817-type optocouplers. IC Role / Device Role / Timing Role: Shunt regulator providing precise 2.5 V reference to optocoupler LED cathode, linearizing CTR vs. output voltage. Use Value: Enables ±1% output voltage regulation across line/load/temperature by stabilizing optocoupler bias point. |
Use Scenario: Adjustable output voltage setting in LM317-style linear regulators. IC Role / Device Role / Timing Role: Precision reference replacing zener diode in ADJ pin feedback network. Use Value: Delivers 0.5% output accuracy and lower thermal drift than 5% zeners, reducing calibration overhead. |
| Overvoltage Protection Circuit | Variable Reference Generator |
|
Use Scenario: Secondary-side overvoltage latch in AC/DC adapters monitoring +12 V or +19 V rails. IC Role / Device Role / Timing Role: Threshold detector triggering SCR crowbar or controller shutdown when VKA exceeds setpoint. Use Value: 20 V max cathode rating and 0.5% VREF tolerance allow reliable trip points within ±0.1 V of target. |
Use Scenario: Programmable reference for ADC biasing or sensor excitation in data acquisition modules. IC Role / Device Role / Timing Role: Adjustable voltage source set between 2.5 V and 20 V using two external resistors. Use Value: Eliminates need for multiple fixed references - one BOM item covers full 2.5–20 V range with <34 mV temp drift. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar adjustable shunt regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TL431BIDBVR (TI) | Same 0.5% VREF tolerance and −40°C to +125°C range, but SOT23-3 package (not SOT23F); 0.3 Ω typical RZ | Compatible pinout for SOT23 footprints, but not drop-in for SOT23F land patterns due to different body dimensions and leadform | Select if board uses standard SOT23 pads and requires TI-qualified supply chain traceability |
| AS431BZTR-E1 (Diodes Inc.) | Identical electrical specs and SOT23F package, but rated only to +105°C ambient and specified with 1% VREF tolerance (A-grade) | Limited to commercial/industrial ambient zones; unsuitable for under-hood or high-temp industrial enclosures | Choose only for cost-sensitive, non-extended-temp applications where 1% tolerance is acceptable |
Compared with TL431BIDBVR and AS431BZTR-E1, ZTL431BFFTA uniquely combines SOT23F mechanical compatibility, 0.5% precision, and full −40°C to +125°C operation - making it optimal for space-constrained, high-reliability isolated power supplies.
Availability
ZTL431BFFTA is available at Aetrix Electronics and suitable for isolated switch-mode power supplies, industrial linear regulators, overvoltage protection circuits, and programmable reference generators requiring stable component supply and guaranteed long-term manufacturability.
Supply support for ZTL431BFFTA 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
Diodes Incorporated is a global manufacturer of discrete semiconductors and analog ICs, specializing in high-reliability power management, signal integrity, and protection solutions for industrial, computing, and consumer markets.
ZTL431BFFTA belongs to Diodes' precision shunt regulator product line, designed specifically to replace zener diodes in feedback, protection, and reference applications demanding tighter tolerance, wider temperature range, and lower dynamic impedance than legacy devices.
FAQ
What is the minimum cathode current required for regulation?
The ZTL431BFFTA requires a minimum cathode current of 0.4 mA to maintain regulation, as specified in the Electrical Characteristics table under IKA(MIN). This ensures stable reference operation even with high-value feedback resistors that limit current draw below 1 mA.
Can ZTL431BFFTA replace a standard 2.5 V zener diode directly?
Yes - ZTL431BFFTA can directly replace a 2.5 V zener in most applications, offering superior 0.5% tolerance, lower dynamic impedance (0.2 Ω vs. >10 Ω), and better temperature stability (±34 mV over −40°C to +125°C vs. ±100+ mV for zeners).
Is external compensation required for stability?
A minimum 4.7 nF capacitor between anode and cathode is recommended to ensure stability across all capacitive loads, per the Stability Boundary graph on page 4 of DS33263. No additional RC network or series resistance is needed for basic operation.
What is the function of Pin 1 (Anode) in SOT23F package?
Pin 1 is the anode terminal and is internally connected to the substrate. The datasheet explicitly states it must be left floating or connected to the anode node - it is not a ground pin and should never be tied to system ground unless also connected to the anode circuit node.
ZTL431BFFTA Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Diodes Incorporated
- Package/Case:
- SOT-23-3 Flat Leads
- Series:
- -
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Reference Type:
- Shunt
- Output Type:
- Adjustable
- Voltage - Output (Min/Fixed):
- 2.5V
- Voltage - Output (Max):
- 20 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:
- 600 µA
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-23F
ZTL431BFFTA FAQ
1.How can I place an order for ZTL431BFFTA through Aetrix?
Please submit a Request for Quotation (RFQ) for ZTL431BFFTA 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 ZTL431BFFTA reliable?
The price and inventory of ZTL431BFFTA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ZTL431BFFTA is usually 5 days.
3.What payment methods are accepted for ZTL431BFFTA?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ZTL431BFFTA transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ZTL431BFFTA?
ZTL431BFFTA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ZTL431BFFTA 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 ZTL431BFFTA?
For technical support, including ZTL431BFFTA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ZTL431BFFTA requirements.
6.How does Aetrix verify that ZTL431BFFTA is sourced from the original manufacturer or authorized distributors?
All ZTL431BFFTA 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 ZTL431BFFTA meets industry standards.
7.What is the process for return or replacement of ZTL431BFFTA?
All ZTL431BFFTA units undergo pre-shipment inspection (PSI). If there is an issue with ZTL431BFFTA, 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 ZTL431BFFTA part is unused and in its original packaging.
Return procedure for ZTL431BFFTA:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
ZTL431BFFTA Tags
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