My Inquiry
My Account
Texas Instruments LM431AIMX/NOPB
- Part No.:
- LM431AIMX/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- Voltage Reference
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LM431AIMX/NOPB.pdf
- Description:
- IC VREF SHUNT ADJ 2.2% 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,312
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
LM431AIMX/NOPB from Texas Instruments is an industrial-grade (–40°C to +85°C) adjustable precision shunt regulator IC, functioning as a programmable 2.485–2.51 V reference with ±17 mV total temperature drift, 0.5 Ω dynamic output impedance, and 1–100 mA cathode current range - used in feedback loops of linear/switching power supplies and voltage monitors.
For engineers reviewing the LM431AIMX/NOPB datasheet, LM431AIMX/NOPB pinout, LM431AIMX/NOPB application, or LM431AIMX/NOPB equivalent, this page delivers verified package mapping (SOIC-8), confirmed thermal performance (RθJA = 126.9°C/W), functional mode details (closed-loop shunt regulation or open-loop comparator), and real-world design constraints including minimum 1 mA cathode current and 37 V absolute max cathode voltage.
Technical Context
The LM431AIMX/NOPB implements a bandgap-referenced error amplifier driving an NPN output stage, enabling precise shunt regulation via external resistor divider on the REF pin. Its internal architecture ensures stable operation across –40°C to +85°C without external compensation under typical load conditions.
It operates in two primary modes: closed-loop regulation (REF tied to output via R1/R2 divider) requiring 1–100 mA cathode current, or open-loop comparator mode (REF driven externally), with fast turn-on response and low-output noise (<10 µVRMS) critical for precision feedback paths.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reference voltage (VREF) | 2.485–2.51 V at 10 mA - defines minimum programmable output (VOUT = VREF × (1 + R1/R2)) and sets accuracy baseline for all adjusted voltages ≥2.5 V |
| Temperature coefficient | Average 50 ppm/°C - ensures ≤17 mV total VREF drift over –40°C to +85°C, enabling stable regulation in industrial environments |
| Dynamic output impedance | 0.5 Ω - maintains tight output voltage regulation despite rapid load transients, reducing need for large output capacitance |
| Cathode current range | 1–100 mA - determines usable input-to-output voltage drop and power dissipation limits (max 0.81 W in SOIC-8 at 25°C) |
| Max cathode voltage | 37 V - sets absolute upper limit for input supply rail in shunt regulator configurations; exceeds 36 V programmable output ceiling |
| Reference input current | 2–4 µA - enables high-impedance feedback networks (e.g., 1 MΩ dividers) with <0.1% error contribution at 25°C |
| ESD rating (HBM) | ±2500 V - requires standard ESD handling but permits direct PCB assembly without special protection circuitry |
Pinout & Package
LM431AIMX/NOPB uses an 8-pin SOIC (D) package (4.90 mm × 3.91 mm body size) with thermal pad omitted; pins 4 and 5 are internally unconnected (NC) and must remain floating. The device dissipates up to 0.81 W at 25°C ambient, derating linearly at 6.5 mW/°C above that temperature.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode (Pin 1) | Output node / shunt current sink | Connects to regulated output rail; carries full load + shunt current; voltage here equals programmed VOUT |
| Reference (Pin 2) | Feedback input / precision voltage sense | High-impedance node (2–4 µA bias); connects to resistor divider midpoint; controls regulation point |
| Anode (Pins 2,3,6,7) | Ground return / current source reference | Internally bonded together; must be connected to system ground; serves as common reference for cathode and REF |
| NC (Pins 4,5) | No internal connection | Must be left unconnected; no routing or copper pour required; does not affect thermal or electrical performance |
Key Features
| Feature | Design Value |
|---|---|
| Adjustable output voltage | Programmable from 2.5 V to 36 V using only two external resistors - eliminates need for multiple fixed-voltage Zener diodes |
| Temperature-compensated reference | Guaranteed stability over full –40°C to +85°C industrial range - avoids recalibration or derating in harsh environments |
| Low dynamic output impedance | 0.5 Ω typical - sustains regulation during fast load steps without added output capacitance or compensation |
| Fast turn-on response | Sub-microsecond activation - supports dynamic enable/disable control in power sequencing and protection circuits |
| Low-output noise | <10 µVRMS wideband - preserves signal integrity in precision analog monitoring and feedback applications |
Applications
| Switch-Mode Power Supply Feedback | Voltage Monitoring & Protection |
|---|---|
|
Use Scenario: Secondary-side voltage sensing in isolated flyback or forward converters, where optocoupler-coupled feedback adjusts primary-side PWM duty cycle. IC Role / Device Role / Timing Role: Precision shunt regulator providing stable 2.5 V reference to drive optocoupler LED; sets exact output voltage via R1/R2 divider. Use Value: Enables ±1% output regulation across line/load/temperature without trimming; replaces discrete Zener + transistor solutions with higher accuracy and lower component count. |
Use Scenario: Overvoltage lockout in battery management systems or DC bus monitoring, triggering shutdown when rail exceeds safe threshold. IC Role / Device Role / Timing Role: Adjustable comparator with hysteresis (via external resistor network), comparing sensed voltage against programmable trip point. Use Value: Achieves accurate, temperature-stable trip points (e.g., 12.6 V ±0.1 V) without calibration; supports both OV and UV detection in single circuit. |
| Current Source/Sink Circuits | Zener Diode Replacement |
|
Use Scenario: Constant-current driver for LEDs or sensor excitation in industrial instrumentation, requiring stable current independent of supply variation. IC Role / Device Role / Timing Role: Shunt regulator configured with floating reference to set precise current through load resistor connected between cathode and supply. Use Value: Delivers 1–100 mA with <0.5% drift over temperature - outperforms discrete transistor-based current sources in accuracy and thermal stability. |
Use Scenario: Voltage reference in analog front-ends or ADC bias networks where fixed 3.3 V or 5 V references are needed with better stability than standard Zeners. IC Role / Device Role / Timing Role: Programmable shunt reference replacing 5% tolerance Zener diodes; configured for exact target voltage (e.g., 3.30 V) using R1/R2. Use Value: Reduces initial tolerance error from ±5% to ±1% and improves temperature drift from 100 ppm/°C to 50 ppm/°C - critical for metrology-grade designs. |
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); tighter VREF tolerance (2.495 V ±0.5%) but higher tempco (92 ppm/°C); same SOIC-8 pinout | Suitable for cost-sensitive consumer power supplies where extended temperature range is unnecessary | Select TL431ACDR only if operating ambient stays within 0–70°C and tighter initial tolerance outweighs thermal drift penalty |
| AS431ASTR-E1 | Industrial-grade (–40°C to +85°C); identical VREF spec (2.485–2.51 V); higher max cathode current (150 mA) but larger SOT-23-3 footprint | Preferred for space-constrained designs needing >100 mA shunt capability, though requires PCB layout change | Choose AS431ASTR-E1 when cathode current exceeds 100 mA or when SOT-23-3 packaging aligns with board density goals |
Compared with TL431ACDR and AS431ASTR-E1, LM431AIMX/NOPB uniquely balances industrial temperature range, moderate VREF tolerance, and SOIC-8 thermal performance - making it optimal for mid-power industrial SMPS feedback where reliability across temperature extremes is non-negotiable.
Availability
LM431AIMX/NOPB is available at Aetrix Electronics and suitable for industrial power supplies, battery protection circuits, and precision analog monitoring systems requiring stable component supply with guaranteed long-term continuity.
Supply support for LM431AIMX/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 leader delivering analog and embedded processing solutions, with decades of expertise in precision reference and power management ICs.
The LM431 product line was designed specifically for high-accuracy, temperature-stable shunt regulation in industrial and automotive power systems - emphasizing robustness, ease of use, and compatibility with legacy Zener-based designs.
FAQ
What is the minimum cathode current required for regulation in LM431AIMX/NOPB?
The LM431AIMX/NOPB requires a minimum cathode current of 1 mA to maintain regulation, as specified in the Recommended Operating Conditions table. Below this threshold, the device exits regulation and output voltage becomes undefined. This value is consistent across the industrial temperature range (–40°C to +85°C) and must be ensured under worst-case conditions - such as lowest input voltage and highest load current - when designing the series resistor (RS) in shunt regulator topologies.
Can LM431AIMX/NOPB be used as a comparator, and how does its performance compare to dedicated comparators?
Yes, LM431AIMX/NOPB can operate in open-loop comparator mode by driving the REF pin externally while leaving the cathode connected to a pull-up resistor. Its propagation delay is sub-microsecond, and input offset is dominated by VREF tolerance (±17 mV over temperature). However, it lacks rail-to-rail output swing and has slower recovery from saturation than purpose-built comparators - so it's best suited for slow-turning thresholds like overvoltage detection, not high-speed signal conditioning.
What is the maximum power dissipation of LM431AIMX/NOPB in SOIC-8 package at 70°C ambient?
At 70°C ambient, LM431AIMX/NOPB's maximum power dissipation is derated from its 25°C rating of 0.81 W. Using the SOIC package derating factor of 6.5 mW/°C, the allowable dissipation is 0.81 W – (6.5 mW/°C × 45°C) = 0.5175 W. Exceeding this risks junction temperature exceeding 150°C, potentially causing thermal shutdown or long-term reliability degradation.
How does the reference input current (IREF) of LM431AIMX/NOPB affect feedback resistor selection?
The LM431AIMX/NOPB reference input current (2–4 µA at 25°C, up to 5.2 µA over temperature) flows into the REF pin and introduces gain error in the R1/R2 divider. To limit this error to <0.1%, total divider resistance should be ≤25 kΩ (e.g., R1 = R2 = 12 kΩ for 5 V output). Higher values increase error and temperature sensitivity - especially critical in precision voltage monitor applications where absolute accuracy matters.
Is LM431AIMX/NOPB RoHS compliant and lead-free?
Yes, LM431AIMX/NOPB is RoHS compliant and lead-free, as confirmed in TI's Package Option Addendum: "RoHS = Yes" and "Lead finish = SN" (matte tin). It meets JEDEC J-STD-020 moisture sensitivity Level-1 (unlimited floor life at ≤30°C/60% RH) and is qualified for lead-free reflow per IPC/JEDEC J-STD-020 standards.
LM431AIMX/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- 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:
- 8-SOIC
LM431AIMX/NOPB FAQ
1.How can I place an order for LM431AIMX/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM431AIMX/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 LM431AIMX/NOPB reliable?
The price and inventory of LM431AIMX/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM431AIMX/NOPB is usually 5 days.
3.What payment methods are accepted for LM431AIMX/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM431AIMX/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM431AIMX/NOPB?
LM431AIMX/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM431AIMX/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 LM431AIMX/NOPB?
For technical support, including LM431AIMX/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM431AIMX/NOPB requirements.
6.How does Aetrix verify that LM431AIMX/NOPB is sourced from the original manufacturer or authorized distributors?
All LM431AIMX/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 LM431AIMX/NOPB meets industry standards.
7.What is the process for return or replacement of LM431AIMX/NOPB?
All LM431AIMX/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM431AIMX/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 LM431AIMX/NOPB part is unused and in its original packaging.
Return procedure for LM431AIMX/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM431AIMX/NOPB Tags
-
TL431AIDBZR
Texas Instruments
-
TL431BQDBZR
Texas Instruments
-
AN431AN-ATRG1
Diodes Incorporated
-
LM4040CYM3-2.5-TR
Microchip Technology
-
LM4040CYM3-4.1-TR
Microchip Technology
-
LM4040EIM3-2.5/NOPB
Texas Instruments
-
AZ431LBNTR-G1
Diodes Incorporated
-
LM4040D20IDBZR
Texas Instruments
-
LM4041DIM3-ADJ/NOPB
Texas Instruments
-
LM4040DIM3X-2.5/NOPB
Texas Instruments
-
LM4040DIM3-2.5/NOPB
Texas Instruments
-
AZ431LANTR-G1
Diodes Incorporated
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
