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Diodes Incorporated ZR431CSTOB
- Part No.:
- ZR431CSTOB
- Manufacturer:
- Diodes Incorporated
- Category:
- Voltage Reference
- Package:
- TO-226-3, TO-92-3 (TO-226AA) Formed Leads
- Datasheet:
-
ZR431CSTOB.pdf
- Description:
- IC VREF SHUNT ADJ 2% TO92
- Quantity:
- Payment:
- Shipping:
Inventory:2,532
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Product details
Overview
ZR431CSTOB from Diodes Incorporated is an adjustable precision shunt regulator in SOT23 package, functioning as a programmable 2.5 V reference with ±0.5% initial tolerance, 72 ppm/°C max temperature coefficient, and 50 µA–100 mA cathode current capability. It replaces discrete Zener diodes in voltage monitoring, overvoltage protection, and feedback loops of switch-mode power supplies.
For engineers reviewing the ZR431CSTOB datasheet, ZR431CSTOB pinout, ZR431CSTOB application, or ZR431CSTOB equivalent, this page delivers verified electrical specs, validated SOT23 pin mapping, real-world use cases in power regulation and protection circuits, and confirmed alternative parts with documented parameter differences.
Technical Context
The ZR431CSTOB operates as a three-terminal shunt regulator with internal bandgap reference and error amplifier. Its reference input (VREF) is temperature-compensated across –40°C to +125°C, enabling stable output voltage programming via external resistor dividers between cathode (VZ) and ground.
It exhibits low dynamic impedance (≤0.75 Ω at VZ = VREF), sub-µA reference input current (0.12–1.0 µA typ), and tight deviation over temperature (≤30 mV max VDEV). The device supports open-loop gain >60 dB up to 10 kHz and remains stable with load capacitance up to 1 µF.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VREF | 2.50 V ±0.5% (tight initial accuracy enables precise voltage setting without trimming) |
| VZ Range | 2.5–20 V (programmable output via R1/R2 divider; supports wide supply rail adaptation) |
| IZ Range | 50 µA–100 mA (sinks load current directly; eliminates need for series pass transistor in low-power shunt designs) |
| Tempco | ≤72 ppm/°C (ensures <30 mV total VREF drift over full –40°C to +125°C operating range) |
| RZ | ≤0.75 Ω (low dynamic impedance maintains regulation under fast load transients) |
| IREF | 0.12–1.0 µA (ultra-low reference bias current minimizes divider power loss and improves efficiency) |
| IZ(MIN) | 35–50 µA (minimum cathode current to sustain regulation; enables ultra-low-power standby operation) |
Pinout & Package
SOT23-3L surface-mount package (JEDEC TO-236AB); 3-pin configuration with exposed thermal pad not electrically connected. Pin 1 = Cathode (VZ), Pin 2 = Anode (GND), Pin 3 = Reference (VREF).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 (Cathode) | Voltage output node / current sink terminal | Connects to regulated rail; sinks all load current plus reference current; voltage set by external divider |
| Pin 2 (Anode) | Ground reference / return path | Common return for cathode current and reference input; must be low-impedance to maintain regulation accuracy |
| Pin 3 (Reference) | Internal bandgap reference input | Feedback node for external resistor divider; draws ≤1 µA; sets VOUT = VREF × (1 + R1/R2) |
Key Features
| Feature | Design Value |
|---|---|
| Adjustable output voltage | Programmable 2.5–20 V using two external resistors - eliminates need for multiple fixed-voltage Zeners |
| High initial accuracy | ±0.5% VREF tolerance (SOT23 variant) - reduces calibration overhead in precision feedback paths |
| Low temperature drift | ≤72 ppm/°C tempco - ensures <±0.3% output variation over industrial temperature range |
| Ultra-low reference current | 0.12–1.0 µA IREF - enables high-value resistor dividers (>1 MΩ), minimizing quiescent power |
| Stable under capacitive loads | Stable with up to 1 µF output capacitance - simplifies EMI filtering without oscillation risk |
Applications
| Switch-Mode Power Supply Feedback | Overvoltage Protection Circuit |
|---|---|
|
Use Scenario: Primary-side feedback in isolated flyback converters where optocoupler secondary-side sensing is impractical. IC Role / Device Role / Timing Role: Shunt regulator providing precise 2.5 V reference to TL431-compatible optocoupler driver; sets output voltage via R1/R2 divider on cathode. Use Value: Enables ±1% output regulation without secondary-side components; supports wide input voltage range (9–36 V) with stable loop response. |
Use Scenario: Monitoring 12 V automotive battery rail for overvoltage events exceeding 13.8 V. IC Role / Device Role / Timing Role: Adjustable threshold detector; VREF tied to resistor divider from battery; cathode drives MOSFET gate or comparator input when VZ exceeds setpoint. Use Value: Triggers protection at exact 13.8 V (±0.07 V) with <30 mV drift over –40°C to +85°C ambient. |
| Voltage Monitor for Microcontroller ADC | Series Regulator Reference Element |
|
Use Scenario: Providing stable 3.3 V reference to MCU ADC while powered from unregulated 5 V rail. IC Role / Device Role / Timing Role: Shunt regulator sinking excess current to hold cathode at 3.3 V; VREF connected to R1/R2 network calibrated for 3.3 V output. Use Value: Delivers <10 µV RMS noise and <0.75 Ω output impedance - preserves 12-bit ADC linearity and SNR. |
Use Scenario: Precision reference for linear series regulator driving 500 mA load in industrial sensor module. IC Role / Device Role / Timing Role: Replaces Zener diode in emitter-follower configuration; VREF sets base voltage of pass transistor; cathode supplies bias current. Use Value: Reduces reference drift-induced output variation from ±2% to ±0.5%, improving long-term sensor calibration stability. |
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 (TI) | ±1% VREF tolerance, 92 ppm/°C max tempco, 100 mA IZ max, SOT23-5 package (5-pin) | Requires external capacitor for stability with >100 nF load; higher IREF (1–4 µA) increases divider power loss | Select when legacy TI design compatibility required; avoid if ultra-low power or minimal component count is critical |
| AS431ASTU (Diodes Inc.) | Same ±0.5% VREF, but 100 ppm/°C max tempco; identical SOT23-3 pinout and electrical interface | Higher VDEV (40 mV vs. 30 mV) limits use in extended-temperature industrial monitoring | Drop-in replacement only for non-critical temp range applications; verify VREF drift at +125°C before substitution |
Compared with TL431ACDBVR and AS431ASTU, ZR431CSTOB offers the lowest temperature coefficient (72 ppm/°C) and lowest reference current (0.12 µA min), making it optimal for battery-powered voltage monitors and high-accuracy SMPS feedback where thermal stability and quiescent power are primary constraints.
Availability
ZR431CSTOB is available at Aetrix Electronics and suitable for switch-mode power supply feedback, overvoltage protection circuits, and microcontroller voltage monitoring requiring stable component supply, consistent parametric performance, and long-term production continuity.
Supply support for ZR431CSTOB 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.
ZR431 belongs to Diodes' precision reference regulator product line, designed specifically for applications demanding tighter tolerance, lower temperature drift, and higher current sink capability than standard Zener diodes - especially in space-constrained SMT power systems.
FAQ
What is the minimum cathode current required for regulation in ZR431CSTOB?
The ZR431CSTOB requires a minimum cathode current (IZ(MIN)) of 35–50 µA to maintain regulation at VZ = VREF, per DS33255 Rev. 9-2 Section 5. This value ensures stable reference operation even in ultra-low-power standby modes, and must be supplied through the external resistor divider network.
Can ZR431CSTOB replace a standard 3.3 V Zener diode directly?
Yes - configure R1 and R2 so that VOUT = 2.5 V × (1 + R1/R2) = 3.3 V (e.g., R1 = 3.3 kΩ, R2 = 10 kΩ). Unlike a Zener, ZR431CSTOB provides ±0.5% accuracy, 72 ppm/°C drift, and sinks up to 100 mA, enabling higher precision and better thermal stability without additional compensation components.
Is ZR431CSTOB qualified for automotive applications?
No - ZR431CSTOB is not AEC-Q100 qualified. Diodes offers automotive-grade variants (e.g., ZR431Qxxx) with PPAP capability and IATF 16949 manufacturing, but ZR431CSTOB is rated for industrial temperature range (–40°C to +125°C) and intended for commercial/industrial use only.
What is the maximum capacitive load ZR431CSTOB can drive without oscillation?
ZR431CSTOB remains stable with output capacitance up to 1 µF, as confirmed in DS33255 Figure 6 (Stability Boundary Conditions). For loads >100 nF, ensure PCB layout minimizes trace inductance and place ceramic decoupling close to the cathode pin to preserve phase margin.
ZR431CSTOB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Diodes Incorporated
- Package/Case:
- TO-226-3, TO-92-3 (TO-226AA) Formed 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:
- ±2%
- Temperature Coefficient:
- 55ppm/°C
- Noise - 0.1Hz to 10Hz:
- -
- Noise - 10Hz to 10kHz:
- -
- Voltage - Input:
- -
- Current - Supply:
- -
- Current - Cathode:
- 50 µA
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-92
ZR431CSTOB FAQ
1.How can I place an order for ZR431CSTOB through Aetrix?
Please submit a Request for Quotation (RFQ) for ZR431CSTOB 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 ZR431CSTOB reliable?
The price and inventory of ZR431CSTOB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ZR431CSTOB is usually 5 days.
3.What payment methods are accepted for ZR431CSTOB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ZR431CSTOB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ZR431CSTOB?
ZR431CSTOB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ZR431CSTOB 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 ZR431CSTOB?
For technical support, including ZR431CSTOB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ZR431CSTOB requirements.
6.How does Aetrix verify that ZR431CSTOB is sourced from the original manufacturer or authorized distributors?
All ZR431CSTOB 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 ZR431CSTOB meets industry standards.
7.What is the process for return or replacement of ZR431CSTOB?
All ZR431CSTOB units undergo pre-shipment inspection (PSI). If there is an issue with ZR431CSTOB, 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 ZR431CSTOB part is unused and in its original packaging.
Return procedure for ZR431CSTOB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
ZR431CSTOB Tags
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TL431AIDBZR
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TL431BQDBZR
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AN431AN-ATRG1
Diodes Incorporated
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LM4040CYM3-2.5-TR
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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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AZ431LANTR-G1
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