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Diodes Incorporated ZR431LF02TC
- Part No.:
- ZR431LF02TC
- Manufacturer:
- Diodes Incorporated
- Category:
- Voltage Reference
- Package:
- TO-236-3, SC-59, SOT-23-3
- Datasheet:
-
ZR431LF02TC.pdf
- Description:
- IC VREF SHUNT ADJ 2.5% SOT23
- Quantity:
- Payment:
- Shipping:
Inventory:3,647
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Product details
Overview
ZR431LF02TC from Diodes Incorporated is a 2.5% tolerance, adjustable precision shunt regulator in SOT23 package, featuring 1.24 V reference voltage, 50 ppm/°C max temperature coefficient, and 100 µA–25 mA cathode current capability; it serves as a programmable voltage reference in feedback loops of switch-mode power supplies generating 3.3 V or 3 V outputs.
For engineers reviewing the ZR431LF02TC datasheet, ZR431LF02TC pinout, ZR431LF02TC application, or ZR431LF02TC equivalent, key selection criteria include reference voltage accuracy, dynamic output impedance (≤2 Ω), temperature stability over –40°C to +85°C, and compatibility with external resistor programming for output voltages from 1.24 V to 10 V.
Technical Context
The ZR431LF02TC implements a bandgap-based, temperature-compensated reference core with internal error amplifier and NPN pass transistor, enabling stable regulation across –40°C to +85°C operating range. Its cathode-voltage-dependent reference deviation (ΔVZ ≤ 2 mV/V) and low reference input current (0.02–0.4 µA) support high-impedance feedback networks.
It operates as a two-terminal shunt device when used with external resistors, but functions as a three-terminal regulator in series or overvoltage protection configurations. The 30 Ω internal series resistance and 0.01 µF bypass capacitor recommendation ensure loop stability in SMPS feedback paths.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reference Voltage | 1.24 V ±2.5% - sets base threshold for programmable output; enables 3.3 V/3 V supply generation with R1/R2 divider |
| Temp Coefficient | ≤50 ppm/°C - ensures <±8 mV drift over full –40°C to +85°C range, critical for stable feedback in industrial power supplies |
| Cathode Current Range | 100 µA to 25 mA - supports low-power monitoring and higher-current shunt regulation without external boost |
| Dynamic Impedance | 0.25–2 Ω - minimizes output voltage perturbation under load transients; improves PSRR in regulated rails |
| Min Regulating Current | 30–100 µA - defines lowest usable current before regulation loss; enables ultra-low-power biasing |
| Off-state Current | 10–30 µA at VZ = 10 V - ensures minimal leakage when disabled, preserving system standby efficiency |
Pinout & Package
SOT23-3 surface-mount package (3.0 × 1.35 × 1.0 mm), lead-free and RoHS-compliant, with standard thermal pad layout per AP02001.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode (Pin 1) | Output/Regulated Node | Connects to SMPS feedback node or voltage divider top; sinks current to maintain VREF at ADJ pin |
| Anode (Pin 2) | Ground Reference | Return path for reference current; must be low-impedance ground for stable regulation |
| Reference (Pin 3) | Feedback Input | High-impedance (≤0.4 µA) input sensing divider voltage; triggers regulation when ≥1.24 V |
Key Features
| Feature | Design Value |
|---|---|
| Programmable Output Voltage | 1.24 V to 10 V via external R1/R2 - eliminates need for multiple fixed zeners and simplifies BOM for multi-rail systems |
| Low Reference Input Current | 0.02–0.4 µA - permits use of high-value resistors (e.g., 1 MΩ) in feedback dividers, reducing power loss and noise sensitivity |
| Temperature Compensation | Full-range operation (–40°C to +85°C) with ≤8 mV VREF drift - ensures consistent regulation in automotive and industrial ambient conditions |
| Dynamic Output Impedance | 0.25–2 Ω - maintains tight output voltage control during fast load steps, critical for digital IC supply stability |
Applications
| Switch-Mode Power Supply Feedback | Voltage Monitor / Supervisor |
|---|---|
Use Scenario: Used in secondary-side feedback loop of isolated DC-DC converters to regulate 3.3 V or 3 V output rails. IC Role / Device Role / Timing Role: Adjustable shunt regulator providing precise 1.24 V reference to optocoupler input, closing voltage control loop. Use Value: Enables accurate, temperature-stable output regulation with <±1% total error over line/load/temperature, replacing less stable zener diodes. | Use Scenario: Monitors microcontroller I/O rail to trigger reset if voltage drops below 2.7 V or rises above 3.6 V. IC Role / Device Role / Timing Role: Dual-threshold comparator reference source using two independent resistor dividers on REF pin. Use Value: Delivers matched, low-drift thresholds without external references-reducing component count and board space vs. discrete solutions. |
| Overvoltage Protection Circuit | Series Regulator Control Element |
Use Scenario: Protects downstream 5 V logic from input surges up to 12 V in industrial sensor interfaces. IC Role / Device Role / Timing Role: Shunt element that triggers crowbar or shutdown when sensed voltage exceeds 5.5 V threshold. Use Value: Provides fast, repeatable trip point (±2.5%) with <10 µs response to overvoltage events due to low dynamic impedance. | Use Scenario: Controls pass transistor base in linear post-regulator stage following a switching pre-regulator. IC Role / Device Role / Timing Role: Precision reference driving error amplifier that compares output to VREF and adjusts pass device conduction. Use Value: Achieves <0.5% output accuracy and <10 mV ripple rejection by leveraging stable 1.24 V reference and low-noise architecture. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar adjustable shunt regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TL431ACDBVR | 1% initial tolerance, 39 ppm/°C typical tempco, 100 mA max cathode current | Better accuracy and higher current drive; requires larger PCB footprint (SOT-23-6 vs SOT23-3) | Preferred where tighter regulation (<±0.5%) or >25 mA sink capability is required |
| AS431ASTZTR-G1 | 2.5% tolerance, 50 ppm/°C max, 30 mA max cathode current, different pinout (Anode/Ref/Cathode = Pin 1/2/3) | Same functional role but reversed Anode/Ref pin assignment - requires PCB layout revision | Select only if sourcing constraints require Active-Semi supply chain; verify pin compatibility before design-in |
Compared with TL431ACDBVR and AS431ASTZTR-G1, ZR431LF02TC offers identical 2.5% tolerance and thermal performance in a smaller SOT23-3 footprint, but lower max cathode current (25 mA vs 100/30 mA); best suited for space-constrained, cost-sensitive SMPS feedback where 25 mA sink suffices.
Availability
ZR431LF02TC is available at Aetrix Electronics and suitable for switch-mode power supplies, voltage supervisors, overvoltage protection circuits, and series regulator control requiring stable component supply with guaranteed long-term availability.
Supply support for ZR431LF02TC 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 devices for industrial, computing, and consumer markets.
The ZR431L product line delivers precision shunt regulation with enhanced temperature stability and low quiescent current, designed specifically for feedback control and voltage monitoring in compact, cost-sensitive power systems.
FAQ
What is the minimum cathode current required for regulation in ZR431LF02TC?
The ZR431LF02TC requires a minimum cathode current of 30 µA to maintain regulation at the reference pin. This value is specified across the full temperature range and ensures stable operation even in ultra-low-power monitoring applications where feedback divider currents are minimized.
Can ZR431LF02TC replace a standard 3.3 V zener diode directly?
No direct replacement is possible without external resistors. ZR431LF02TC is a three-terminal adjustable shunt regulator requiring R1/R2 feedback network to set output voltage. To replicate a 3.3 V zener, connect R1 = 16.2 kΩ and R2 = 10 kΩ between cathode, reference, and anode to achieve VOUT = 3.3 V with 1.24 V reference.
How does the dynamic output impedance affect SMPS feedback stability?
With dynamic impedance of 0.25–2 Ω, ZR431LF02TC minimizes AC voltage variation at the feedback node during load transients. This reduces phase shift in the optocoupler-coupled loop, improving phase margin and preventing oscillation-especially critical in high-frequency flyback and forward converters.
Is ZR431LF02TC qualified for automotive applications?
While ZR431LF02TC operates from –40°C to +85°C and meets AEC-Q200 stress test recommendations for passive components, it is not officially AEC-Q100 qualified as an active IC. For automotive use, Diodes Incorporated recommends the pin-compatible ZR431LQ02TA variant, which carries full AEC-Q100 Grade 1 qualification.
ZR431LF02TC Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Diodes Incorporated
- Package/Case:
- TO-236-3, SC-59, SOT-23-3
- Series:
- -
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Reference Type:
- Shunt
- Output Type:
- Adjustable
- Voltage - Output (Min/Fixed):
- 1.24V
- Voltage - Output (Max):
- 10 V
- Current - Output:
- 25 mA
- Tolerance:
- ±2.5%
- Temperature Coefficient:
- 50ppm/°C
- Noise - 0.1Hz to 10Hz:
- -
- Noise - 10Hz to 10kHz:
- -
- Voltage - Input:
- -
- Current - Supply:
- -
- Current - Cathode:
- 100 µA
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-23-3
ZR431LF02TC FAQ
1.How can I place an order for ZR431LF02TC through Aetrix?
Please submit a Request for Quotation (RFQ) for ZR431LF02TC 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 ZR431LF02TC reliable?
The price and inventory of ZR431LF02TC are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ZR431LF02TC is usually 5 days.
3.What payment methods are accepted for ZR431LF02TC?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ZR431LF02TC transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ZR431LF02TC?
ZR431LF02TC orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ZR431LF02TC 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 ZR431LF02TC?
For technical support, including ZR431LF02TC datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ZR431LF02TC requirements.
6.How does Aetrix verify that ZR431LF02TC is sourced from the original manufacturer or authorized distributors?
All ZR431LF02TC 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 ZR431LF02TC meets industry standards.
7.What is the process for return or replacement of ZR431LF02TC?
All ZR431LF02TC units undergo pre-shipment inspection (PSI). If there is an issue with ZR431LF02TC, 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 ZR431LF02TC part is unused and in its original packaging.
Return procedure for ZR431LF02TC:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
ZR431LF02TC Tags
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TL431BQDBZR
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