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Texas Instruments LM431CIZ/NOPB
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- Part No.:
- LM431CIZ/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- Voltage Reference
- Package:
- TO-226-3, TO-92-3 (TO-226AA)
- Datasheet:
-
LM431CIZ/NOPB.pdf
- Description:
- IC VREF SHUNT -0.6%/+0.4% TO92-3
- Quantity:
- Payment:
- Shipping:
Inventory:8,927
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Product details
Overview
LM431CIZ/NOPB from Texas Instruments is a 3-terminal adjustable precision shunt regulator with 2.5 V reference voltage, ±17 mV reference deviation over temperature, 0.5 Ω dynamic output impedance, and operation up to 36 V cathode voltage - used in voltage monitoring, current sink circuits, and as Zener diode replacement in linear power supplies.
For engineers reviewing the LM431CIZ/NOPB datasheet, LM431CIZ/NOPB pinout, LM431CIZ/NOPB application, or LM431CIZ/NOPB equivalent, this page delivers verified electrical specs, TO-92 package terminal mapping, real-world use cases, and validated alternative parts for precision shunt regulation design.
Technical Context
The LM431CIZ/NOPB operates as a programmable shunt reference using an internal bandgap reference and transconductance amplifier. Its reference pin senses external resistor-divider feedback, enabling output voltage adjustment from 2.5 V to 36 V via two external resistors.
It functions in closed-loop regulation (with feedback divider) or open-loop comparator mode. Minimum cathode current is 0.4 mA; maximum is 100 mA. Thermal hysteresis is induced by package stress, not circuit topology.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reference voltage (VREF) | 2.485–2.51 V at 25°C - sets base accuracy of adjustable output; determines minimum programmable voltage |
| Reference voltage deviation | ±17 mV over full temperature range - defines worst-case output setpoint error without trimming |
| Dynamic output impedance | 0.5 Ω at DC - ensures stable regulation under load transients; lower than most discrete Zeners |
| Cathode voltage range | 2.5 V to 36 V - enables wide-range output programming with external resistors |
| Minimum cathode current | 0.4 mA - lowest current sustaining regulation; critical for low-power bias networks |
| OFF-state cathode current | 0.3–1 μA at 36 V - enables ultra-low quiescent current in shutdown or monitoring modes |
| Average tempco | 50 ppm/°C - quantifies drift per degree; supports stable performance across industrial temperature range |
Pinout & Package
LM431CIZ/NOPB uses the TO-92 (LP) 3-pin through-hole package (4.30 mm × 4.30 mm body), rated for 0.78 W internal power dissipation at 25°C with 6.2 mW/°C derating above ambient.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Ground reference node | Internally connected to substrate; must be tied to system ground for proper regulation |
| Cathode | Shunt current output / regulated voltage node | Carries total current (load + shunt); voltage at this pin equals programmed output (VZ) |
| Reference | Feedback input | Senses voltage divider ratio; regulates when divider output = VREF (≈2.5 V) |
Key Features
| Feature | Design Value |
|---|---|
| Temperature-compensated reference | Stable 2.5 V reference over –40°C to +85°C without external compensation components |
| Low dynamic output impedance | 0.5 Ω enables tight voltage regulation during fast load steps - superior to standard Zener diodes |
| Fast turn-on response | Enables use in overvoltage crowbar and delay timer circuits where rapid conduction onset is required |
| Low-output noise | Supports precision analog sensing and reference applications where ripple-induced error must be minimized |
| Space-saving TO-92 package | Compatible with legacy through-hole assembly; footprint matches common 3-pin regulators and Zeners |
Applications
| Adjustable Linear Power Supply | Voltage Monitoring Circuit |
|---|---|
Use Scenario: Regulating output of a transformer-rectifier-filter stage with user-selectable voltage via potentiometer. IC Role / Device Role / Timing Role: Shunt regulator controlling cathode voltage by sinking excess current; reference pin monitors output via resistive divider. Use Value: Replaces discrete Zener + transistor combo with single IC, reducing BOM count and improving thermal stability. |
Use Scenario: Detecting overvoltage on a 12 V automotive rail before it damages downstream logic. IC Role / Device Role / Timing Role: Precision threshold detector - cathode drives MOSFET gate when input exceeds 13.5 V setpoint. Use Value: Achieves ±1% trip accuracy over temperature without calibration, leveraging 50 ppm/°C tempco. |
| Current Sink for LED Bias | Zener Diode Replacement |
Use Scenario: Providing constant 20 mA bias to high-brightness LEDs in industrial signage. IC Role / Device Role / Timing Role: Two-resistor configured as constant-current sink - reference pin grounded, cathode to LED anode, anode to ground. Use Value: Delivers stable current independent of supply variation (15–24 V), eliminating need for ballast resistors. |
Use Scenario: Upgrading legacy 5.1 V Zener-based voltage clamp in a microcontroller reset circuit. IC Role / Device Role / Timing Role: Programmable shunt reference replacing fixed-voltage Zener; same TO-92 footprint and pinout. Use Value: Improves accuracy from ±5% to ±0.7% and reduces temperature drift by 3× versus standard Zener diodes. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar shunt regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TL431CDBZR | SO-8 package; 2.495 V reference (±0.5% initial tolerance); 0.22 Ω dynamic impedance; requires PCB rework for TO-92 replacement | Higher precision and lower impedance, but surface-mount only - unsuitable for through-hole legacy designs | Select TL431CDBZR only if redesigning for SMT and requiring tighter initial tolerance or lower impedance. |
| AS431ARTDT-33 | TO-92 package; 2.5 V reference (±1%); 1.5 Ω dynamic impedance; -20°C to +70°C operating range | Same through-hole form factor but narrower temperature range and higher impedance - acceptable for commercial-grade cost-sensitive designs | Choose AS431ARTDT-33 when TO-92 compatibility is mandatory and industrial temperature range is not required. |
Compared with TL431CDBZR and AS431ARTDT-33, LM431CIZ/NOPB uniquely balances TO-92 mechanical compatibility, –40°C to +85°C operation, and 0.5 Ω impedance - making it optimal for industrial retrofit and legacy board upgrades where pin-for-pin replacement and wide temperature support are essential.
Availability
LM431CIZ/NOPB is available at Aetrix Electronics and suitable for adjustable power supplies, voltage monitoring systems, and current sink circuits requiring stable component supply with long-term industrial temperature support.
Supply support for LM431CIZ/NOPB 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 specializing in analog and embedded processing technologies, with leadership in precision analog ICs and power management solutions.
The LM431 product line was designed for high-accuracy shunt regulation in space-constrained and thermally demanding applications - targeting industrial power supplies, safety-critical monitoring, and Zener replacement scenarios.
FAQ
What is the operating temperature range of the LM431CIZ/NOPB?
The LM431CIZ/NOPB is rated for operation from –40°C to +85°C, matching the industrial temperature grade. This range is confirmed in the TI datasheet's Recommended Operating Conditions table and applies specifically to the CIZ variant with TO-92 packaging.
Can the LM431CIZ/NOPB replace a standard 5.1 V Zener diode directly?
Yes - the LM431CIZ/NOPB can replace a 5.1 V Zener in TO-92 format by configuring R1 and R2 to set VOUT = 5.1 V using VOUT = VREF(1 + R1/R2). Its 2.5 V reference and 0.5 Ω impedance provide superior accuracy and stability versus discrete Zeners.
What is the minimum cathode current required for regulation in the LM431CIZ/NOPB?
The LM431CIZ/NOPB requires a minimum cathode current of 0.4 mA to maintain regulation, as specified in the Electrical Characteristics table under IZ(MIN). Below this, the device exits regulation and output voltage drops unpredictably.
Does the LM431CIZ/NOPB require an external capacitor for stability?
No external capacitor is required for basic shunt regulation, but TI recommends a 0.1 µF ceramic bypass capacitor near the cathode for noise reduction. Stability boundaries depend on external R-C network values and load capacitance, as shown in Figure 2 of the datasheet.
How does the reference input current affect accuracy in the LM431CIZ/NOPB?
The LM431CIZ/NOPB has a reference input current of 2–4 µA at 25°C. This current flows into the reference pin and introduces error in high-impedance resistor dividers; accuracy improves when R1||R2 ≤ 10 kΩ to limit voltage drop error to <1 mV.
LM431CIZ/NOPB 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):
- 37 V
- Current - Output:
- 100 mA
- Tolerance:
- -0.6%, +0.4%
- Temperature Coefficient:
- 50ppm/°C Typical
- 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:
- Through Hole
- Supplier Device Package:
- TO-92-3
LM431CIZ/NOPB FAQ
1.How can I place an order for LM431CIZ/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM431CIZ/NOPB 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 LM431CIZ/NOPB reliable?
The price and inventory of LM431CIZ/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM431CIZ/NOPB is usually 5 days.
3.What payment methods are accepted for LM431CIZ/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM431CIZ/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM431CIZ/NOPB?
LM431CIZ/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM431CIZ/NOPB 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 LM431CIZ/NOPB?
For technical support, including LM431CIZ/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM431CIZ/NOPB requirements.
6.How does Aetrix verify that LM431CIZ/NOPB is sourced from the original manufacturer or authorized distributors?
All LM431CIZ/NOPB 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 LM431CIZ/NOPB meets industry standards.
7.What is the process for return or replacement of LM431CIZ/NOPB?
All LM431CIZ/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM431CIZ/NOPB, 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 LM431CIZ/NOPB part is unused and in its original packaging.
Return procedure for LM431CIZ/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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