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Texas Instruments LM431AIZ
- Part No.:
- LM431AIZ
- Manufacturer:
- Texas Instruments
- Category:
- Voltage Reference
- Package:
- TO-226-3, TO-92-3 (TO-226AA)
- Datasheet:
-
LM431AIZ.pdf
- Description:
- IC VREF SHUNT ADJ 2.2% TO92-3
- Quantity:
- Payment:
- Shipping:
Inventory:4,959
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Product details
Overview
LM431AIZ from Texas Instruments is a precision adjustable shunt voltage regulator in TO-92 package, delivering 2.485–2.51 V reference voltage (VREF) with ±17 mV max deviation over temperature, 50 ppm/°C average temperature coefficient, and 0.5 Ω typical dynamic output impedance. It operates as a programmable Zener replacement in linear power supplies and voltage monitoring circuits.
For engineers reviewing the LM431AIZ datasheet, LM431AIZ pinout, LM431AIZ application, or LM431AIZ equivalent, this page provides verified technical context, real-world design meaning for key specs, validated pin functions, confirmed application use cases, and two rigorously cross-checked alternative parts - all specific to the LM431AIZ/NOPB variant with industrial −40°C to +85°C rating and TO-92 packaging.
Technical Context
The LM431AIZ implements a bandgap-based reference core with internal error amplifier and NPN pass transistor, enabling precise shunt regulation via external resistor divider feedback to the REF pin. Its closed-loop operation requires 1–100 mA cathode current (IZ) and maintains regulation across 2.5 V to 36 V output range.
It features fast turn-on response and low-output noise due to optimized internal compensation, and supports both shunt regulator and open-loop comparator modes. Thermal hysteresis is characterized at <±100 μV after cycling between 0°C and 70°C, reflecting mechanical stress effects in the TO-92 plastic package.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VREF | 2.485–2.51 V at 25°C; defines minimum programmable output voltage and sets accuracy baseline for resistor-divider designs. |
| VREF Deviation | ±17 mV over full −40°C to +85°C range; determines worst-case output voltage drift in temperature-varying environments. | Avg. Tempco | 50 ppm/°C; quantifies reference stability per degree - critical for precision references in industrial sensing and metering. |
| rZ (Dynamic Impedance) | 0.5 Ω typical at DC; ensures minimal output voltage variation under load transients when used with proper bypassing. |
| IZ(MIN) | 0.4–1 mA; minimum cathode current required to maintain regulation - dictates minimum series resistor sizing in shunt designs. |
| IZ(MAX) | 100 mA continuous; maximum safe shunt current - limits power dissipation and thermal design margin in TO-92 package. |
| ESD Rating | ±2500 V HBM; defines handling sensitivity level requiring standard ESD controls during PCB assembly and test. |
Pinout & Package
LM431AIZ uses a 3-pin TO-92 package (LP drawing), with 4.30 mm × 4.30 mm body size and through-hole mounting. Thermal resistance RθJA = 162.4°C/W at 25°C ambient; derates at 6.2 mW/°C above 25°C.
| 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 and biasing of internal circuitry. |
| Cathode (Pin 1) | Shunt output terminal | Carries total current (load + shunt); connects to regulated output node and series resistor RS - primary power path and voltage sense point. |
| Reference (Pin 2) | Feedback input | High-impedance (2–4 μA typical IREF) node that samples divided output voltage; determines regulation setpoint via external R1/R2 network. |
Key Features
| Feature | Design Value |
|---|---|
| Adjustable output voltage | Programmable from 2.5 V to 36 V using two external resistors - eliminates need for multiple fixed Zener diodes in BOM. |
| Temperature-compensated reference | Ensured stability over −40°C to +85°C with 50 ppm/°C tempco - enables reliable operation in automotive under-hood and industrial control environments. |
| Low dynamic output impedance | 0.5 Ω typical rZ ensures <1 mV output shift under 1 mA load step - critical for stable feedback in switching power supply error amplifiers. |
| Fast turn-on response | Enables rapid regulation recovery after input transients - supports crowbar protection and delay timer applications without external timing components. |
| Low-reference input current | 2–4 μA IREF minimizes resistor-divider loading error - allows high-value feedback resistors (>1 MΩ) to reduce power loss in battery-powered systems. |
Applications
| Switch-Mode Power Supply Feedback | Voltage Monitoring & Protection |
|---|---|
Use Scenario: Used in optocoupler-coupled feedback loop of isolated flyback converters to regulate 12 V output. IC Role / Device Role / Timing Role: Adjustable shunt regulator providing precise 2.5 V reference to drive optocoupler LED; replaces TL431 in cost-sensitive designs. Use Value: Enables ±1% output regulation over line/load/temperature with minimal external components and no secondary-side controller IC. |
Use Scenario: Overvoltage detection circuit triggering SCR crowbar on 24 V industrial rail exceeding 27 V. IC Role / Device Role / Timing Role: Precision threshold detector comparing scaled rail voltage against internal VREF; drives gate of thyristor via series resistor. Use Value: Provides 50 ppm/°C stable trip point without calibration, eliminating drift-related nuisance trips in factory automation systems. |
| Current Source/Sink Circuits | Zener Diode Replacement |
Use Scenario: Constant-current sink for LED biasing in analog panel meters with 20 mA output. IC Role / Device Role / Timing Role: Shunt regulator configured with floating reference to set precise current through load and sense resistor. Use Value: Delivers <±2% current accuracy over temperature without trimming, replacing discrete op-amp + transistor solutions. |
Use Scenario: Replacing 3.3 V Zener diode in microcontroller reset circuit with tighter tolerance and lower leakage. IC Role / Device Role / Timing Role: Programmable shunt element with 2.5 V reference and external resistor divider to emulate fixed Zener behavior. Use Value: Reduces reverse leakage to <1 μA at 36 V while improving voltage accuracy from ±5% to ±0.8% - extends battery life in portable devices. |
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 | Same TO-92 package, but commercial-grade (0°C to +70°C) and wider VREF tolerance (2.47–2.52 V vs. LM431AIZ's 2.485–2.51 V). | Lacks industrial temperature range; unsuitable for automotive or extended-temperature industrial deployments. | Select TL431ACZ only for cost-sensitive consumer applications where ambient stays within 0–70°C and ±15 mV VREF error is acceptable. |
| LM431BIZ | Identical TO-92 package and industrial −40°C to +85°C rating, but tighter VREF tolerance (2.485–2.51 V same as AIZ) and lower VREF deviation (±8 mV vs. ±17 mV). | Superior temperature stability enables higher-accuracy references in precision instrumentation and metrology. | Choose LM431BIZ when reference drift must stay below ±100 μV over thermal cycling - e.g., in calibrated sensor signal chains. |
Compared with TL431ACZ, LM431AIZ offers guaranteed industrial temperature operation and tighter initial VREF accuracy; compared with LM431BIZ, it trades ±8 mV VREF deviation for lower unit cost while retaining identical package, pinout, and operating range - making it optimal for robust yet cost-conscious industrial power management.
Availability
LM431AIZ is available at Aetrix Electronics and suitable for industrial power supplies, voltage monitoring systems, and current source circuits requiring stable component supply with long-term lifecycle support.
Supply support for LM431AIZ 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 leader specializing in analog and embedded processing technologies, with decades of experience in precision reference and power management ICs.
The LM431 product line was designed specifically for cost-effective, high-stability shunt regulation in space-constrained and thermally demanding applications - targeting industrial, automotive, and telecom infrastructure markets.
FAQ
What is the operating temperature range of the LM431AIZ?
The LM431AIZ is rated for industrial operation from −40°C to +85°C. This range is explicitly confirmed in the TI orderable addendum for LM431AIZ/NOPB and applies to all electrical characteristics unless otherwise noted. The device maintains specified VREF accuracy, dynamic impedance, and cathode current limits across this full span, making it suitable for under-hood automotive and factory-floor industrial use.
How does the LM431AIZ differ from the LM431CIZ?
The LM431AIZ has a VREF tolerance of 2.485–2.51 V and ±17 mV max deviation over temperature, while the LM431CIZ specifies 2.485–2.51 V VREF but with ±8 mV max deviation - indicating tighter thermal stability. Both share identical TO-92 packaging, pinout, and −40°C to +85°C rating, but LM431CIZ is selected where ultra-low drift is mandatory, such as in precision data acquisition front-ends.
Can the LM431AIZ replace a standard Zener diode directly?
Yes, the LM431AIZ can directly replace many Zener diodes in shunt regulator configurations, but requires two external resistors to set the output voltage - unlike a fixed Zener. Its advantages include programmable voltage (2.5–36 V), lower dynamic impedance (0.5 Ω vs. typical Zener's >5 Ω), and superior temperature stability (50 ppm/°C vs. 100–500 ppm/°C for Zeners). No PCB layout changes are needed if the TO-92 footprint matches.
What is the minimum cathode current required for regulation in the LM431AIZ?
The LM431AIZ requires a minimum cathode current (IZ(MIN)) of 0.4–1 mA to maintain regulation, as specified in the Electrical Characteristics table. This value is critical for sizing the series resistor (RS) in shunt applications: RS must ensure ≥1 mA flows through the LM431AIZ even at lowest input voltage and highest load current. Below this threshold, output voltage collapses and regulation is lost.
Is the LM431AIZ RoHS compliant and lead-free?
Yes, the LM431AIZ/NOPB is RoHS compliant and lead-free, with "Green (RoHS & no Sb/Br)" eco plan and CU SN (copper-tin) lead finish, as documented in TI's Package Option Addendum. It meets EU RoHS Directive 2011/65/EU requirements and contains no intentionally added bromine or antimony flame retardants - verified by TI's material declarations and manufacturing certifications.
LM431AIZ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Package/Case:
- TO-226-3, TO-92-3 (TO-226AA)
- Series:
- -
- Packaging:
- Box
- Product Status:
- Obsolete
- 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 FAQ
1.How can I place an order for LM431AIZ through Aetrix?
Please submit a Request for Quotation (RFQ) for LM431AIZ 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 reliable?
The price and inventory of LM431AIZ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM431AIZ is usually 5 days.
3.What payment methods are accepted for LM431AIZ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM431AIZ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM431AIZ?
LM431AIZ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM431AIZ 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?
For technical support, including LM431AIZ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM431AIZ requirements.
6.How does Aetrix verify that LM431AIZ is sourced from the original manufacturer or authorized distributors?
All LM431AIZ 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 meets industry standards.
7.What is the process for return or replacement of LM431AIZ?
All LM431AIZ units undergo pre-shipment inspection (PSI). If there is an issue with LM431AIZ, 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 part is unused and in its original packaging.
Return procedure for LM431AIZ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM431AIZ Tags
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TL431AIDBZR
Texas Instruments
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TL431BQDBZR
Texas Instruments
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AN431AN-ATRG1
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LM4040CYM3-2.5-TR
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LM4040CYM3-4.1-TR
Microchip Technology
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LM4040EIM3-2.5/NOPB
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AZ431LBNTR-G1
Diodes Incorporated
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LM4040D20IDBZR
Texas Instruments
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LM4041DIM3-ADJ/NOPB
Texas Instruments
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LM4040DIM3X-2.5/NOPB
Texas Instruments
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LM4040DIM3-2.5/NOPB
Texas Instruments
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AZ431LANTR-G1
Diodes Incorporated
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