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Texas Instruments LM431AIM3X/NOPB
- Part No.:
- LM431AIM3X/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- Voltage Reference
- Package:
- TO-236-3, SC-59, SOT-23-3
- Datasheet:
-
LM431AIM3X/NOPB.pdf
- Description:
- IC VREF SHUNT ADJ 2.2% SOT23-3
- Quantity:
- Payment:
- Shipping:
Inventory:5,047
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Product details
Overview
LM431AIM3X/NOPB from Texas Instruments is an adjustable precision shunt regulator IC with 2.5 V reference voltage, ±17 mV reference voltage deviation over temperature, 0.5 Ω dynamic output impedance, 1 mA minimum cathode current for regulation, and −40°C to +85°C industrial operating range. It functions as a programmable Zener replacement in feedback loops of linear and switching power supplies.
For engineers reviewing the LM431AIM3X/NOPB datasheet, LM431AIM3X/NOPB pinout, LM431AIM3X/NOPB application, or LM431AIM3X/NOPB equivalent, key selection criteria include reference accuracy across temperature, low dynamic impedance for stable regulation, SOT-23-3 package compatibility with space-constrained PCB layouts, and guaranteed turn-on response for protection circuits.
Technical Context
The LM431AIM3X/NOPB implements a precision bandgap-based reference with internal error amplifier and NPN pass transistor, enabling adjustable output voltage (2.5 V to 36 V) via external resistor divider. Its architecture ensures stable closed-loop operation with 1–100 mA cathode current and supports open-loop comparator use by driving the reference pin externally.
Temperature compensation is embedded in the die-level design, yielding average 50 ppm/°C reference drift and ≤17 mV total deviation over −40°C to +85°C. The device maintains low-noise, low-impedance regulation without requiring bypass capacitors-though a 0.1 µF ceramic capacitor on the cathode improves noise immunity.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reference Voltage (VREF) | 2.485 V to 2.51 V at 25°C - defines minimum programmable output and sets accuracy baseline for feedback networks |
| Reference Voltage Deviation | ±17 mV over −40°C to +85°C - determines worst-case output voltage tolerance in temperature-varying environments |
| Dynamic Output Impedance | 0.5 Ω at DC - enables tight load regulation and fast transient response in shunt-based feedback paths |
| Min Cathode Current (IZ(MIN)) | 0.4 mA to 1 mA - establishes lowest viable bias current for stable regulation in low-power designs |
| Cathode Voltage Range | 2.5 V to 36 V - defines maximum output voltage span achievable with external resistors R1/R2 |
| ESD Rating (HBM) | ±2500 V - indicates robustness during handling and board assembly without special ESD precautions |
| Package | SOT-23-3 - 2.92 mm × 1.30 mm footprint ideal for compact power supply feedback and voltage monitoring circuits |
Pinout & Package
SOT-23-3 package: 3-pin surface-mount plastic package with gull-wing leads, 1.30 mm body width, and thermal pad not present. Designed for reflow soldering per Level-1-260°C MSL rating.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode | Output / Shunt Node | Connects to regulated voltage node; sinks current to ground to maintain setpoint; carries full load + shunt current |
| Anode | Ground Reference | Common return path for internal reference and error amplifier; must be low-impedance connection to system ground |
| Reference | Feedback Input | High-impedance input (≤4 μA) that senses divided output voltage; sets regulation point via R1/R2 ratio |
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 |
| Low Dynamic Output Impedance | 0.5 Ω typical - minimizes output voltage shift under varying load or line conditions in feedback control loops |
| Fast Turn-On Response | Enables use in overvoltage crowbar and delay timer circuits - responds rapidly to threshold violations without external timing components |
| Temperature-Compensated Reference | 50 ppm/°C average TC and ±17 mV total deviation over −40°C to +85°C - ensures stable setpoint in industrial environments |
| Low-Noise Operation | No external capacitor required for stability - simplifies layout and reduces BOM count in cost-sensitive power designs |
Applications
| Switch-Mode Power Supply Feedback | Voltage Monitoring & Protection |
|---|---|
Use Scenario: Regulating output of isolated flyback or forward converter via optocoupler-coupled feedback loop. IC Role / Device Role / Timing Role: Precision shunt regulator providing stable 2.5 V reference to drive optocoupler LED; sets primary-side regulation threshold. Use Value: Enables ±1% output accuracy over line, load, and temperature while maintaining galvanic isolation and minimizing component count. |
Use Scenario: Detecting overvoltage condition on a 12 V rail to trigger shutdown or crowbar circuit. IC Role / Device Role / Timing Role: Adjustable threshold comparator with built-in reference; triggers SCR gate when cathode voltage exceeds programmed level. Use Value: Provides accurate, temperature-stable trip point without external precision references or op-amps - reduces failure risk in safety-critical systems. |
| Current Source/Sink Circuits | Zener Diode Replacement |
Use Scenario: Generating stable 10 mA constant current for LED bias or sensor excitation. IC Role / Device Role / Timing Role: Shunt regulator configured with floating reference to force fixed current through load connected between cathode and supply. Use Value: Delivers <1% current variation over temperature and supply voltage changes - outperforms discrete transistor-current-source topologies. |
Use Scenario: Replacing 3.3 V Zener diode in microcontroller reset circuit where tighter voltage tolerance is required. IC Role / Device Role / Timing Role: Programmable shunt element with 2.5 V reference and resistor divider to emulate precise Zener behavior at non-standard voltages. Use Value: Achieves 2.5% initial accuracy vs. typical 5% Zener tolerance, with lower dynamic impedance for improved noise rejection in reset assertion. |
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 dynamic impedance, 0.6 mA min cathode current, same SOT-23-3 package | Better reference accuracy and lower impedance, but narrower −20°C to +70°C temp range vs. LM431AIM3X/NOPB's −40°C to +85°C | Select TL431ACDBVR for commercial-grade designs prioritizing tighter voltage tolerance; verify thermal margin in extended-temp environments. |
| AS431ASTZTR-G1 | 2.5 V reference (±1%), 0.5 Ω dynamic impedance, 1 mA min cathode current, TO-92 and SOT-23 packages available | Same regulation performance but only rated for 0°C to +70°C; RoHS-compliant but lacks TI's long-term industrial qualification history | Choose AS431ASTZTR-G1 for cost-sensitive consumer applications where industrial temperature range is unnecessary. |
Compared with TL431ACDBVR and AS431ASTZTR-G1, the LM431AIM3X/NOPB offers superior industrial temperature support (−40°C to +85°C) and proven reliability in power supply feedback, making it preferred for automotive and industrial OEM designs despite slightly wider reference tolerance.
Availability
LM431AIM3X/NOPB is available at Aetrix Electronics and suitable for switch-mode power supply feedback, voltage monitoring & protection, current source/sink circuits, and Zener diode replacement applications requiring stable component supply and long-term industrial-grade availability.
Supply support for LM431AIM3X/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 headquartered in Dallas, Texas, delivering analog and embedded processing solutions for industrial, automotive, and personal electronics markets.
The LM431 product line was designed as a precision, temperature-stable shunt regulator family to replace traditional Zener diodes in feedback, protection, and reference applications across industrial power systems.
FAQ
What is the reference voltage tolerance of LM431AIM3X/NOPB over temperature?
The LM431AIM3X/NOPB has a reference voltage (VREF) of 2.485 V to 2.51 V at 25°C and exhibits ±17 mV total deviation over its full −40°C to +85°C operating range. This corresponds to approximately ±0.68% max deviation relative to nominal 2.5 V, ensuring predictable regulation in industrial environments without external calibration.
Can LM431AIM3X/NOPB be used as a comparator?
Yes, the LM431AIM3X/NOPB can operate in open-loop mode as a comparator by applying an external voltage to the reference pin while holding cathode and anode at fixed potentials. Its sharp turn-on characteristic and low reference input current (≤4 μA) enable reliable threshold detection, as confirmed in Section 8.4 of the official datasheet.
What is the minimum cathode current required for regulation in LM431AIM3X/NOPB?
The LM431AIM3X/NOPB requires a minimum cathode current (IZ(MIN)) of 0.4 mA to 1 mA to maintain regulation, depending on temperature and unit variation. Below this threshold, the device exits regulation and output voltage rises toward cathode supply rail - critical for sizing series bias resistors in low-power applications.
Does LM431AIM3X/NOPB require an output capacitor for stability?
No, the LM431AIM3X/NOPB does not require an output capacitor for basic regulation stability. Its internal compensation and low dynamic impedance (0.5 Ω) ensure stable operation with purely resistive feedback. However, a 0.1 µF ceramic capacitor placed close to the cathode improves high-frequency noise rejection in noisy power environments.
What package type and marking does LM431AIM3X/NOPB use?
The LM431AIM3X/NOPB uses the SOT-23-3 package (2.92 mm × 1.30 mm) with lead finish of matte tin (SN) and moisture sensitivity level (MSL) 1. Its top-marking is "N1E", as specified in TI's Package Option Addendum, confirming industrial-grade −40°C to +85°C operation and RoHS compliance.
LM431AIM3X/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
LM431AIM3X/NOPB FAQ
1.How can I place an order for LM431AIM3X/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM431AIM3X/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 LM431AIM3X/NOPB reliable?
The price and inventory of LM431AIM3X/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM431AIM3X/NOPB is usually 5 days.
3.What payment methods are accepted for LM431AIM3X/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM431AIM3X/NOPB transactions.
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4.How is shipping managed for LM431AIM3X/NOPB?
LM431AIM3X/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM431AIM3X/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 LM431AIM3X/NOPB?
For technical support, including LM431AIM3X/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM431AIM3X/NOPB requirements.
6.How does Aetrix verify that LM431AIM3X/NOPB is sourced from the original manufacturer or authorized distributors?
All LM431AIM3X/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 LM431AIM3X/NOPB meets industry standards.
7.What is the process for return or replacement of LM431AIM3X/NOPB?
All LM431AIM3X/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM431AIM3X/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 LM431AIM3X/NOPB part is unused and in its original packaging.
Return procedure for LM431AIM3X/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM431AIM3X/NOPB Tags
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