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Texas Instruments LM431AIM3/NOPB
- Part No.:
- LM431AIM3/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- Voltage Reference
- Package:
- TO-236-3, SC-59, SOT-23-3
- Datasheet:
-
LM431AIM3/NOPB.pdf
- Description:
- IC VREF SHUNT ADJ 2.2% SOT23-3
- Quantity:
- Payment:
- Shipping:
Inventory:2,442
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Product details
Overview
LM431AIM3/NOPB from Texas Instruments is an adjustable precision shunt regulator IC with 2.5 V reference voltage, ±17 mV reference voltage deviation over temperature (−40°C to +85°C), 0.5 Ω typical dynamic output impedance, 1 mA minimum cathode current for regulation, and SOT-23-3 package. It replaces Zener diodes in voltage monitoring and feedback circuits for switching power supplies.
For engineers reviewing the LM431AIM3/NOPB datasheet, LM431AIM3/NOPB pinout, LM431AIM3/NOPB application, or LM431AIM3/NOPB equivalent, this page delivers verified specifications, validated pin functions, confirmed thermal performance (RθJA = 267.7°C/W), and real-world use cases including overvoltage protection and precision current sinking.
Technical Context
The LM431AIM3/NOPB operates as a 3-terminal programmable shunt regulator using an internal bandgap reference and transconductance amplifier to maintain stable output voltage via external resistor divider feedback. Its sharp turn-on response and low-output noise enable fast transient regulation without external compensation in most configurations.
It supports closed-loop operation where the reference pin senses output voltage through R1/R2, and open-loop comparator mode when driven by external signals. The device requires only 1 mA minimum cathode current to sustain regulation and exhibits −1.4 mV/V voltage coefficient from VREF to 10 V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reference Voltage (VREF) | 2.485–2.51 V at 25°C; defines minimum programmable output voltage threshold |
| Reference Voltage Deviation | ±17 mV over −40°C to +85°C; ensures stable setpoint across industrial temperature range |
| Dynamic Output Impedance | 0.5 Ω typical at DC; maintains tight voltage regulation under load transients |
| Min Cathode Current (IZ(MIN)) | 0.4–1 mA; sets minimum bias current required to enter regulation mode |
| Cathode Voltage Range | 2.5 V to 36 V; enables wide-range programmability using two external resistors |
| ESD Rating (HBM) | ±2500 V; meets standard handling requirements for automated assembly |
| Thermal Resistance (RθJA) | 267.7°C/W for SOT-23 package; determines maximum power dissipation at ambient temperature |
Pinout & Package
SOT-23-3 package: 3-pin surface-mount plastic case (2.92 mm × 1.30 mm body), lead-free (RoHS-compliant), moisture sensitivity level 1, peak reflow 260°C.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode | Output / Shunt terminal | Connects to regulated voltage node; sinks current to ground to maintain setpoint |
| Anode | Ground reference | Typically tied to system ground; forms return path for shunt current |
| Reference | Feedback input | Monitors divided output voltage; triggers regulation when ≥2.485 V |
Key Features
| Feature | Design Value |
|---|---|
| Temperature-compensated reference | Ensures <50 ppm/°C average TC and ±17 mV total drift over −40°C to +85°C |
| Low dynamic output impedance | 0.5 Ω typical enables <10 mV load regulation error across 1–100 mA cathode current |
| Fast turn-on response | Sharp knee characteristic allows immediate regulation onset above VREF, eliminating startup delay |
| Low-output noise | Reduces ripple coupling into sensitive analog circuits like ADC references or sensor interfaces |
| Space-saving SOT-23 package | 2.92 mm × 1.30 mm footprint supports high-density PCB layouts in compact power modules |
Applications
| Switching Power Supply Feedback | Voltage Monitoring Circuit |
|---|---|
Use Scenario: Secondary-side voltage sensing in isolated flyback converters to regulate output without optocoupler. IC Role / Device Role / Timing Role: Adjustable shunt regulator providing precise feedback to PWM controller via optocoupler LED drive. Use Value: Enables ±1% output accuracy across line/load/temperature with minimal external components. |
Use Scenario: Overvoltage detection in battery management systems triggering shutdown at 4.3 V. IC Role / Device Role / Timing Role: Precision voltage comparator with hysteresis implemented via resistor network on reference pin. Use Value: Delivers 10 mV threshold resolution and stable trip point over −40°C to +85°C. |
| Current Sink for LED Bias | Crowbar Overvoltage Protection |
Use Scenario: Constant-current driver for indicator LEDs in industrial HMIs requiring stable brightness. IC Role / Device Role / Timing Role: Shunt-based current sink where cathode connects to LED anode and reference sets current via Rsense. Use Value: Maintains ±3% current accuracy despite supply variation from 5 V to 24 V. |
Use Scenario: Fast-acting crowbar circuit protecting FPGA I/O rails during surge events. IC Role / Device Role / Timing Role: Triggers SCR gate when sensed voltage exceeds 3.3 V ±2%, clamping rail before damage occurs. Use Value: Sub-100 ns response time prevents >3.6 V excursion on protected 3.3 V rail. |
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 | 2.495 V reference (±0.5%), 0.22 Ω rZ, −40°C to +125°C rating, same SOT-23-3 package | Higher accuracy and extended temperature range; lower dynamic impedance improves regulation at high frequencies | Select TL431ACDBVR for designs requiring tighter initial tolerance or automotive-grade operation |
| AS431ASTZTR-G1 | 2.5 V reference (±0.5%), 0.3 Ω rZ, −40°C to +85°C, SOT-23-3, 2.5 μA max IREF | Lower reference input current reduces divider loading error; optimized for ultra-low-power monitoring | Choose AS431ASTZTR-G1 when minimizing quiescent current in battery-powered voltage monitors |
Compared with LM431AIM3/NOPB, TL431ACDBVR offers superior accuracy and thermal range but higher cost, while AS431ASTZTR-G1 trades slight VREF tolerance for significantly lower IREF, improving divider ratio stability in high-impedance sensing networks.
Availability
LM431AIM3/NOPB is available at Aetrix Electronics and suitable for switching power supply feedback, voltage monitoring, current sink circuits, and crowbar protection requiring stable component supply across industrial temperature ranges.
Supply support for LM431AIM3/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 series was designed as a drop-in replacement for discrete Zener diodes in feedback, monitoring, and protection circuits-emphasizing temperature stability, low noise, and ease of programmability across consumer, industrial, and computing applications.
FAQ
What is the reference voltage tolerance of LM431AIM3/NOPB over temperature?
The LM431AIM3/NOPB has a reference voltage (VREF) of 2.485–2.51 V at 25°C and exhibits ±17 mV total deviation over the full −40°C to +85°C operating range. This corresponds to approximately 43 ppm/°C average temperature coefficient, meeting industrial-grade stability requirements without external trimming.
Can LM431AIM3/NOPB be used as a comparator?
Yes, LM431AIM3/NOPB can operate in open-loop comparator mode. When the reference pin is driven externally (not via resistor divider), it compares that voltage to its internal 2.485 V threshold and switches the cathode between high-impedance and low-impedance states. This enables overvoltage detection and delay timing functions without additional ICs.
What is the minimum cathode current needed for regulation in LM431AIM3/NOPB?
The LM431AIM3/NOPB requires a minimum cathode current (IZ(MIN)) of 0.4–1 mA to maintain regulation. Below this threshold, the device exits regulation and cathode voltage rises uncontrollably. Designers must size the series resistor to ensure ≥1 mA flows even at minimum input voltage and maximum load current.
How does the dynamic output impedance affect LM431AIM3/NOPB performance?
The LM431AIM3/NOPB has a typical dynamic output impedance (rZ) of 0.5 Ω at DC. This low value ensures minimal voltage shift (<50 mV) under 100 mA cathode current changes, directly improving load regulation in shunt-based feedback loops and current sink applications where stability is critical.
Is LM431AIM3/NOPB RoHS compliant and lead-free?
Yes, LM431AIM3/NOPB is RoHS compliant and lead-free. Per TI's packaging addendum, it features Sn (tin) lead finish, meets JEDEC Level-1 moisture sensitivity, and is rated for peak reflow at 260°C. The part marking "N1E" on the SOT-23 body confirms this RoHS-compliant variant.
LM431AIM3/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Package/Case:
- TO-236-3, SC-59, SOT-23-3
- Series:
- -
- Packaging:
- Tape & Reel (TR)
- 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:
- Surface Mount
- Supplier Device Package:
- SOT-23-3
LM431AIM3/NOPB FAQ
1.How can I place an order for LM431AIM3/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM431AIM3/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 LM431AIM3/NOPB reliable?
The price and inventory of LM431AIM3/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM431AIM3/NOPB is usually 5 days.
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4.How is shipping managed for LM431AIM3/NOPB?
LM431AIM3/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM431AIM3/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 LM431AIM3/NOPB?
For technical support, including LM431AIM3/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM431AIM3/NOPB requirements.
6.How does Aetrix verify that LM431AIM3/NOPB is sourced from the original manufacturer or authorized distributors?
All LM431AIM3/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 LM431AIM3/NOPB meets industry standards.
7.What is the process for return or replacement of LM431AIM3/NOPB?
All LM431AIM3/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM431AIM3/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 LM431AIM3/NOPB part is unused and in its original packaging.
Return procedure for LM431AIM3/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM431AIM3/NOPB Tags
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