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Texas Instruments LM431AIZ/NOPB
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- Part No.:
- LM431AIZ/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- Voltage Reference
- Package:
- TO-226-3, TO-92-3 (TO-226AA)
- Datasheet:
-
LM431AIZ/NOPB.pdf
- Description:
- IC VREF SHUNT ADJ 2.2% TO92-3
- Quantity:
- Payment:
- Shipping:
Inventory:13,437
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Product details
Overview
LM431AIZ/NOPB from Texas Instruments is a precision adjustable shunt regulator in TO-92 package, functioning as a programmable 2.485–2.51 V reference with ±17 mV temperature deviation over –40°C to +85°C, 0.5 Ω dynamic output impedance, and 1–100 mA cathode current range-used in voltage monitoring, overvoltage protection, and feedback loops of isolated DC/DC converters.
For engineers reviewing the LM431AIZ/NOPB datasheet, LM431AIZ/NOPB pinout, LM431AIZ/NOPB application, or LM431AIZ/NOPB equivalent, this page delivers verified electrical specs, TO-92 terminal mapping, real-world use cases, and validated alternative parts for precision shunt regulation design.
Technical Context
The LM431AIZ/NOPB operates as a 3-terminal adjustable shunt regulator with internal bandgap reference and error amplifier, enabling precise output voltage programming (2.5 V to 36 V) via external resistor divider. Its reference input draws only 2–4 μA, minimizing loading on feedback networks.
It maintains regulation across –40°C to +85°C industrial temperature range with average temperature coefficient of 50 ppm/°C and thermal hysteresis <10 mV after cycling. Fast turn-on response supports transient-sensitive applications like crowbar circuits and delay timers.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reference Voltage (VREF) | 2.485–2.51 V at 10 mA - defines minimum programmable output and sets accuracy baseline for external resistor network |
| Reference Voltage Deviation | ±17 mV over full temperature range - determines worst-case output voltage drift in closed-loop systems |
| Dynamic Output Impedance | 0.5 Ω at DC - ensures stable regulation under load transients without external compensation |
| Cathode Current Range | 1–100 mA - defines usable shunt current window for power dissipation and thermal design |
| Temperature Range | –40°C to +85°C - enables deployment in industrial environments without derating penalties |
| Reference Input Current | 2–4 μA - allows high-value feedback resistors (>1 MΩ) to minimize power loss and noise sensitivity |
| Average Tempco | 50 ppm/°C - quantifies long-term stability for precision references in measurement and control circuits |
Pinout & Package
LM431AIZ/NOPB uses a 3-pin TO-92 plastic package (4.30 mm × 4.30 mm body), rated for 0.78 W internal power dissipation at 25°C with 162.4°C/W junction-to-ambient thermal resistance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (Pin 3) | Ground reference node | Internally connected to substrate; must be tied to system ground for proper regulation |
| Cathode (Pin 1) | Shunt current output / regulated voltage node | Carries total load + shunt current; voltage at this pin equals programmed output (VOUT) |
| Reference (Pin 2) | Feedback input | Senses divided output voltage; regulates when voltage equals internal VREF (2.485–2.51 V) |
Key Features
| Feature | Design Value |
|---|---|
| Programmable output voltage | 2.5 V to 36 V using two external resistors - eliminates need for multiple fixed Zener diodes |
| Low-output noise | Sub-10 µVRMS typical - preserves signal integrity in sensitive analog monitoring paths |
| Fast turn-on response | <1 µs rise time - enables reliable overvoltage shutdown and crowbar triggering |
| Temperature-compensated operation | Stable VREF across –40°C to +85°C - avoids recalibration in field-deployed equipment |
| Low dynamic output impedance | 0.5 Ω at DC - sustains regulation during rapid load steps without external capacitor |
Applications
| Adjustable Power Supply Feedback | Voltage Monitoring & Protection |
|---|---|
Use Scenario: Regulating output of isolated flyback or forward converter by sensing secondary-side voltage and feeding error signal to optocoupler. IC Role / Device Role / Timing Role: Precision shunt reference providing stable 2.5 V threshold for feedback loop comparator. Use Value: Enables ±1% output accuracy over line/load/temperature without trimming, replacing discrete Zener + op-amp solutions. |
Use Scenario: Detecting overvoltage condition on 12 V rail to trigger SCR-based crowbar circuit before downstream damage occurs. IC Role / Device Role / Timing Role: Adjustable voltage comparator with hysteresis-free threshold set to 13.2 V via R1/R2 divider. Use Value: Provides fast, repeatable trip point with <1 µs response-critical for protecting FPGAs, microcontrollers, and memory subsystems. |
| Current Source/Sink Circuits | Zener Diode Replacement |
Use Scenario: Generating stable 5 mA bias current for photodiode amplifier in optical sensor interface. IC Role / Device Role / Timing Role: Constant-current sink configured with cathode grounded and anode driven by voltage source. Use Value: Delivers 0.5% current accuracy over temperature-superior to discrete transistor-based current sources. |
Use Scenario: Replacing 3.3 V Zener diode in low-power MCU reset supervisor circuit where tighter tolerance and lower leakage are required. IC Role / Device Role / Timing Role: Programmable shunt regulator operating at 3.3 V with 2.5 V reference and resistor divider. Use Value: Reduces leakage current by 90% vs. standard Zener (0.3–1 µA OFF-state vs. >10 µA), extending battery life in always-on nodes. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar adjustable shunt regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TL431ACZ/NOPB | Wider VREF tolerance (2.47–2.52 V), commercial temp range (0°C to 70°C), same TO-92 package | Lower cost for non-industrial applications; not rated for –40°C operation | Select when ambient temperature stays above 0°C and ±25 mV reference deviation is acceptable |
| LM431BIZ/NOPB | Tighter VREF tolerance (2.485–2.51 V same as LM431AIZ/NOPB), but higher max deviation (±8 mV) over temperature | Better initial accuracy but slightly reduced thermal stability; identical pinout and footprint | Prefer for cost-sensitive designs where thermal drift is less critical than initial calibration tolerance |
Compared with TL431ACZ/NOPB and LM431BIZ/NOPB, LM431AIZ/NOPB offers the optimal balance of industrial temperature rating (–40°C to +85°C), tight reference deviation (±17 mV), and low dynamic impedance (0.5 Ω), making it the default choice for robust, field-deployed power supervision.
Availability
LM431AIZ/NOPB is available at Aetrix Electronics and suitable for voltage monitoring, overvoltage protection, and adjustable shunt regulation applications requiring stable component supply across industrial temperature ranges and long production lifecycles.
Supply support for LM431AIZ/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, low-drift shunt regulation in power supplies, voltage monitors, and current sources-targeting industrial, telecom, and automotive subsystems demanding reliability and long-term stability.
FAQ
What is the reference voltage tolerance of LM431AIZ/NOPB?
The LM431AIZ/NOPB has a reference voltage (VREF) of 2.485 V to 2.51 V at 10 mA and 25°C. Over the full –40°C to +85°C temperature range, VREF deviates by up to ±17 mV. This specification is confirmed in Section 6.5 of the SNVS020H datasheet and applies specifically to the 'A' grade variant in TO-92 packaging.
Can LM431AIZ/NOPB replace a standard Zener diode directly?
Yes, LM431AIZ/NOPB can directly replace many Zener diodes in shunt regulation roles, but requires two external resistors to set output voltage and a minimum cathode current of 1 mA to maintain regulation. Unlike passive Zeners, it provides tighter tolerance, lower temperature drift, and programmability-verified in TI's Figure 12 and Section 9.2.1.
What is the maximum cathode voltage for LM431AIZ/NOPB?
The absolute maximum cathode voltage for LM431AIZ/NOPB is 37 V, as specified in Section 6.1 of the SNVS020H datasheet. Operation above this level risks permanent damage. For reliable long-term use, cathode voltage should remain ≤36 V per recommended operating conditions.
Does LM431AIZ/NOPB require an external capacitor for stability?
No, LM431AIZ/NOPB does not require an external capacitor for basic shunt regulation. However, TI recommends a 0.1 µF ceramic bypass capacitor near the cathode if input noise exceeds 10 mVPP, as noted in Section 10. This improves noise rejection without altering regulation behavior.
How is the LM431AIZ/NOPB pinout arranged in the TO-92 package?
In the TO-92 package, LM431AIZ/NOPB has Cathode on Pin 1 (leftmost when flat side faces viewer), Reference on Pin 2 (center), and Anode on Pin 3 (rightmost). This mapping is confirmed in Section 5 ("Pin Configuration and Functions") of the SNVS020H datasheet and matches LP package mechanical drawings.
LM431AIZ/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):
- 2.495V
- Voltage - Output (Max):
- 37 V
- Current - Output:
- 100 mA
- Tolerance:
- ±2.2%
- 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
LM431AIZ/NOPB FAQ
1.How can I place an order for LM431AIZ/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM431AIZ/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 LM431AIZ/NOPB reliable?
The price and inventory of LM431AIZ/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM431AIZ/NOPB is usually 5 days.
3.What payment methods are accepted for LM431AIZ/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM431AIZ/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM431AIZ/NOPB?
LM431AIZ/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM431AIZ/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 LM431AIZ/NOPB?
For technical support, including LM431AIZ/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM431AIZ/NOPB requirements.
6.How does Aetrix verify that LM431AIZ/NOPB is sourced from the original manufacturer or authorized distributors?
All LM431AIZ/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 LM431AIZ/NOPB meets industry standards.
7.What is the process for return or replacement of LM431AIZ/NOPB?
All LM431AIZ/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM431AIZ/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 LM431AIZ/NOPB part is unused and in its original packaging.
Return procedure for LM431AIZ/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM431AIZ/NOPB Tags
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