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Texas Instruments LM431AIM
- Part No.:
- LM431AIM
- Manufacturer:
- Texas Instruments
- Category:
- Voltage Reference
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LM431AIM.pdf
- Description:
- IC VREF SHUNT ADJ 2.2% 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,367
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Product details
Overview
LM431AIM from Texas Instruments is an industrial-grade adjustable precision shunt regulator with 2.485–2.51 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 feedback loops of linear/switching power supplies and voltage monitoring circuits.
For engineers reviewing the LM431AIM datasheet, LM431AIM pinout, LM431AIM application, or LM431AIM equivalent, this page delivers verified electrical specs, SOIC-8 package mapping, thermal derating guidance, and real-world implementation constraints for stable shunt regulation design.
Technical Context
The LM431AIM operates as a 3-terminal programmable Zener replacement, using internal bandgap reference and error amplifier to maintain precise cathode-to-anode voltage via external resistor divider on the reference pin. It requires ≥1 mA cathode current for regulation and supports closed-loop voltage control or open-loop comparator use.
Its architecture enables stable shunt regulation across −40°C to +85°C with average temperature coefficient of 50 ppm/°C and low-output noise. The device exhibits fast turnon response and low dynamic output impedance (0.5 Ω typical), critical for maintaining accuracy under load transients in power supply feedback paths.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reference voltage (VREF) | 2.485–2.51 V at 25°C - sets minimum programmable output voltage and defines feedback divider ratio baseline |
| Reference voltage deviation | ±17 mV over full −40°C to +85°C range - determines worst-case output voltage drift in precision applications |
| Dynamic output impedance | 0.5 Ω typical - ensures minimal output voltage variation under cathode current changes during regulation |
| Cathode voltage range | 2.5 V to 36 V - defines maximum input-to-output differential usable in shunt regulator configurations |
| Minimum cathode current | 0.4–1 mA - establishes lowest bias current required to sustain regulation; impacts series resistor sizing |
| ESD rating (HBM) | ±2500 V - indicates handling robustness during PCB assembly without special ESD precautions beyond standard practice |
| Thermal resistance (RθJA) | 126.9 °C/W (SOIC-8) - used to calculate junction temperature rise and determine safe continuous power dissipation |
Pinout & Package
LM431AIM is packaged in an 8-pin SOIC (D package) with 4.90 mm × 3.91 mm body size and RoHS-compliant lead finish (CuSn). Pins 4 and 5 are internally unconnected (NC); all other pins serve defined regulator functions.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (pins 2, 3, 6, 7) | Ground reference node | Common return path for cathode current and reference input; must be low-impedance connection to system ground |
| Cathode (pin 1) | Regulated output terminal | Shunt current sink point; voltage at this pin is set by external resistor divider and serves as regulated output |
| Reference (pin 8) | Feedback input | High-impedance node sensing divided output voltage; connects to midpoint of R1/R2 divider to close regulation loop |
| NC (pins 4, 5) | No internal connection | Must remain unconnected on PCB; no routing or copper pour required |
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-voltage Zeners |
| Temperature-compensated reference | Stable operation over −40°C to +85°C with 50 ppm/°C avg TC - enables reliable performance in industrial environments |
| Low reference input current | 2–4 μA typical - minimizes divider resistor power loss and improves high-resistance feedback network accuracy |
| Fast turnon response | Enables rapid regulation recovery after line/load transients - critical for maintaining stability in switching power supply feedback |
| Low-output noise | Reduces ripple injection into sensitive analog circuitry when used as precision reference or monitor |
Applications
| Adjustable Switching Power Supply Feedback | Voltage Monitoring Circuit |
|---|---|
Use Scenario: Regulating output of isolated flyback or forward converter where optocoupler feedback references LM431AIM cathode voltage. IC Role / Device Role / Timing Role: Precision shunt regulator providing stable 2.5 V reference to optocoupler LED drive circuit. Use Value: Enables accurate output voltage regulation within ±1% tolerance across temperature and line variations without trimming. |
Use Scenario: Detecting overvoltage condition on 12 V automotive rail using resistor divider and comparator configuration. IC Role / Device Role / Timing Role: Adjustable threshold comparator with temperature-stable reference node driving external transistor or logic gate. Use Value: Provides repeatable 13.2 V trip point with <±50 mV drift over −40°C to +85°C, eliminating mechanical potentiometer calibration. |
| Current Source/Sink Circuit | Zener Diode Replacement |
Use Scenario: Generating constant 10 mA bias current for sensor excitation in industrial transmitters. IC Role / Device Role / Timing Role: Shunt-based current regulator using cathode-to-anode voltage drop and external sense resistor. Use Value: Delivers stable current with <0.5% variation over temperature, replacing discrete op-amp + transistor solutions. |
Use Scenario: Replacing 3.3 V Zener diode in low-power microcontroller reset circuit requiring tighter voltage tolerance. IC Role / Device Role / Timing Role: Programmable shunt reference configured for 3.3 V output via 10 kΩ/12.1 kΩ resistor divider. Use Value: Achieves ±0.5% output accuracy vs. ±5% typical for general-purpose Zeners, improving reset threshold reliability. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar adjustable shunt regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TL431ACDR | Commercial-grade (0°C to 70°C), 2.47–2.52 V VREF, same SOIC-8 package | Limited to non-industrial ambient conditions; lower temperature stability margin | Select when cost sensitivity outweighs extended temperature requirement and thermal drift budget allows |
| LM431BIMX/NOPB | Higher-precision grade (2.485–2.51 V → 2.495–2.505 V), identical SOIC-8 package and temp range | Enables tighter output regulation in high-accuracy power supplies or reference circuits | Choose when reference voltage tolerance must be ≤±5 mV over temperature and layout space is constrained |
Compared with TL431ACDR and LM431BIMX/NOPB, the LM431AIM provides optimal balance of industrial temperature range, ±17 mV reference deviation, and SOIC-8 footprint - making it preferred for embedded power systems requiring long-term stability without premium precision cost.
Availability
LM431AIM is available at Aetrix Electronics and suitable for adjustable power supplies, voltage monitors, and current source circuits requiring stable component supply across industrial temperature ranges and multi-year production cycles.
Supply support for LM431AIM 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 delivering analog and embedded processing solutions for industrial, automotive, and personal electronics markets.
The LM431AIM belongs to TI's precision shunt regulator product line, designed specifically for industrial-grade voltage regulation, feedback control, and reference replacement in space-constrained power systems.
FAQ
What is the operating temperature range of the LM431AIM?
The LM431AIM is rated for industrial operation from −40°C to +85°C. This range is confirmed in the Absolute Maximum Ratings and Recommended Operating Conditions tables of the SNVS020H datasheet. Its temperature-compensated reference ensures stable performance across this full span, distinguishing it from commercial-grade variants like the LM431ACM.
How does the LM431AIM differ from the TL431 in practical design?
The LM431AIM offers tighter reference voltage tolerance (2.485–2.51 V vs. TL431's 2.47–2.52 V), guaranteed industrial temperature range (−40°C to +85°C vs. TL431's 0°C to 70°C), and lower reference input current (2–4 μA vs. up to 4.5 μA). These differences directly impact output accuracy, thermal drift, and feedback network power loss in real designs.
Can the LM431AIM be used as a comparator?
Yes, the LM431AIM can operate in open-loop mode as a comparator. When the reference pin is driven by an external voltage source instead of a feedback divider, the cathode switches between high-impedance and shunt states based on whether the input exceeds VREF. This is documented in Section 8.4 (Device Functional Modes) of the datasheet.
What is the minimum cathode current required for regulation in the LM431AIM?
The LM431AIM requires a minimum cathode current of 0.4–1 mA to maintain regulation, per the IZ(MIN) specification in Section 6.5 of the SNVS020H datasheet. This value must be met under worst-case conditions (e.g., lowest input voltage and highest load current) when selecting the series current-limiting resistor.
Is the LM431AIM pin-compatible with other LM431 variants in SOIC-8?
Yes, all LM431 variants in the SOIC-8 (D) package - including LM431ACM, LM431BIM, and LM431CIM - share identical pinout and footprint. Pin 1 is cathode, pins 2/3/6/7 are anode, pin 4/5 are NC, and pin 8 is reference. This allows direct substitution within the same package family without PCB changes.
LM431AIM Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Series:
- -
- Packaging:
- Tube
- 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:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
LM431AIM FAQ
1.How can I place an order for LM431AIM through Aetrix?
Please submit a Request for Quotation (RFQ) for LM431AIM 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 LM431AIM reliable?
The price and inventory of LM431AIM are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM431AIM is usually 5 days.
3.What payment methods are accepted for LM431AIM?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM431AIM transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM431AIM?
LM431AIM orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM431AIM 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 LM431AIM?
For technical support, including LM431AIM datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM431AIM requirements.
6.How does Aetrix verify that LM431AIM is sourced from the original manufacturer or authorized distributors?
All LM431AIM 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 LM431AIM meets industry standards.
7.What is the process for return or replacement of LM431AIM?
All LM431AIM units undergo pre-shipment inspection (PSI). If there is an issue with LM431AIM, 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 LM431AIM part is unused and in its original packaging.
Return procedure for LM431AIM:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM431AIM Tags
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TL431AIDBZR
Texas Instruments
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TL431BQDBZR
Texas Instruments
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AN431AN-ATRG1
Diodes Incorporated
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LM4040CYM3-2.5-TR
Microchip Technology
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LM4040CYM3-4.1-TR
Microchip Technology
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LM4040EIM3-2.5/NOPB
Texas Instruments
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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
-
AZ431LANTR-G1
Diodes Incorporated
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