My Inquiry
My Account
Texas Instruments LM431AIM/NOPB
- Part No.:
- LM431AIM/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- Voltage Reference
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LM431AIM/NOPB.pdf
- Description:
- IC VREF SHUNT ADJ 2.2% 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:7,995
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
LM431AIM/NOPB from Texas Instruments is an adjustable precision shunt regulator IC with 2.5 V reference voltage, ±17 mV reference deviation over temperature, 0.75 Ω dynamic output impedance, 1 mA minimum cathode current, and −40°C to +85°C industrial operating range - used in feedback loops of isolated DC/DC converters and voltage monitoring circuits.
For engineers reviewing the LM431AIM/NOPB datasheet, LM431AIM/NOPB pinout, LM431AIM/NOPB application, or LM431AIM/NOPB equivalent, this page delivers verified electrical specs, SOIC-8 package mapping, thermal derating guidance, and validated alternative parts for precision shunt regulation design.
Technical Context
The LM431AIM/NOPB operates as a 3-terminal programmable Zener replacement, using internal bandgap reference and error amplifier to regulate cathode-to-anode voltage via external resistor divider. Its reference input (pin 8) senses feedback voltage, while cathode (pin 1) sinks variable current to maintain setpoint.
It functions in closed-loop shunt mode (with R1/R2 divider) or open-loop comparator mode (reference driven externally). Regulation requires 1–100 mA cathode current and remains stable up to 36 V cathode voltage, with average temperature coefficient of 50 ppm/°C.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reference voltage (VREF) | 2.47–2.52 V at 25°C - sets minimum programmable output; actual value defines lower bound of 2.5–36 V adjustment range. |
| Reference deviation over temp | ±17 mV across −40°C to +85°C - determines worst-case output voltage drift in precision feedback applications. |
| Dynamic output impedance | 0.75 Ω at 0 Hz - enables low-noise, high-PSRR regulation critical for sensitive analog power supplies. |
| Min cathode current (IZ(MIN)) | 0.4–1 mA - minimum shunt current required to maintain regulation; dictates minimum load or bias design margin. |
| Cathode voltage range | 2.5 V to 36 V - maximum output voltage achievable with external resistors; supports wide-input industrial SMPS designs. |
| Operating temperature | −40°C to +85°C - industrial-grade thermal rating enabling use in automotive body control and industrial PLCs. |
| ESD rating (HBM) | ±2500 V - defines handling sensitivity; requires ESD-safe assembly practices during board integration. |
Pinout & Package
LM431AIM/NOPB uses an 8-pin SOIC (D) package measuring 4.90 mm × 3.91 mm, rated for 0.81 W internal power dissipation at 25°C with 126.9°C/W junction-to-ambient thermal resistance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode (Pin 1) | Output terminal / current sink | Main regulated node; connects to supply rail and feedback divider; sinks up to 100 mA to maintain VOUT. |
| Anode (Pins 2, 3, 6, 7) | Ground reference / return path | Internally tied anode terminals; must be connected to system ground for proper regulation and thermal conduction. |
| Reference (Pin 8) | Feedback input / voltage sense | High-impedance (≤4 μA input) node that samples divided output voltage; sets regulation point via R1/R2 ratio. |
| NC (Pins 4, 5) | No connect | Not internally bonded; left unconnected on PCB; no routing or thermal considerations 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. |
| Low-output noise | Typical broadband noise <10 μVRMS - preserves signal integrity in precision ADC references and sensor excitation circuits. |
| Fast turn-on response | Turn-on time <1 μs - supports dynamic load transient recovery in switching regulator feedback paths. |
| Temperature-compensated reference | Average TC = 50 ppm/°C - ensures ≤0.1% output drift over full industrial temperature range. |
| Low dynamic output impedance | 0.75 Ω at DC - maintains tight regulation under varying load conditions without external compensation. |
Applications
| Isolated Flyback Feedback | Voltage Monitor with Threshold Alert |
|---|---|
Use Scenario: Secondary-side voltage sensing in optocoupler-coupled flyback converters for medical power supplies. IC Role / Device Role / Timing Role: Precision shunt regulator providing stable 2.5 V reference to drive optocoupler LED, closing primary-side regulation loop. Use Value: Enables ±1% output accuracy across line/load/temperature while meeting IEC 60601 creepage requirements. |
Use Scenario: Overvoltage detection in 24 V industrial control inputs with latchable shutdown. IC Role / Device Role / Timing Role: Adjustable threshold comparator driving SCR gate when sensed voltage exceeds 27.5 V. Use Value: Replaces discrete Zener+transistor circuit with single-component solution, reducing BOM count and layout area by 60%. |
| Current Sink for LED Bias | Three-Terminal Regulator Output Control |
Use Scenario: Constant-current driver for high-brightness indicator LEDs in railway signaling panels. IC Role / Device Role / Timing Role: Shunt-based current sink regulating LED current via cathode-to-ground resistor. Use Value: Delivers 20 mA ±2% current stability over −40°C to +85°C without active thermal compensation. |
Use Scenario: Programmable output voltage adjustment for LM7805-based power rails in test equipment. IC Role / Device Role / Timing Role: External reference replacing LM7805's internal 5 V reference to enable 3.3–12 V output selection. Use Value: Achieves 0.5% output accuracy with minimal external components versus digital DAC-based alternatives. |
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 | 2.495 V reference (±0.5%), 0.22 Ω dynamic impedance, 0.6 mA min cathode current, SOIC-8 package | Higher initial accuracy but narrower industrial temp range (0°C to 70°C); lower dynamic impedance improves PSRR | Select TL431ACDR for cost-sensitive commercial designs requiring tighter initial tolerance and lower impedance |
| AS431ASTU | 2.5 V reference (±1%), 1.2 Ω dynamic impedance, 1 mA min cathode current, SOT-23-3 package | Smaller footprint and lower thermal mass; higher dynamic impedance limits high-frequency ripple rejection | Select AS431ASTU where board space is constrained and thermal cycling is minimal |
Compared with LM431AIM/NOPB, TL431ACDR offers better initial accuracy and lower output impedance but lacks extended temperature support, while AS431ASTU trades thermal robustness and impedance performance for ultra-compact packaging - making LM431AIM/NOPB optimal for industrial environments demanding both precision and reliability.
Availability
LM431AIM/NOPB is available at Aetrix Electronics and suitable for isolated power supplies, voltage supervision systems, and precision current sink circuits requiring stable component supply across extended temperature ranges.
Supply support for LM431AIM/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 specializing in analog, embedded processing, and power management technologies with over 50 years of innovation in precision analog ICs.
The LM431 product line delivers adjustable shunt regulation for feedback, monitoring, and reference applications - designed specifically for industrial, automotive, and telecom power systems requiring long-term stability and wide-temperature operation.
FAQ
What is the reference voltage tolerance of LM431AIM/NOPB at 25°C?
The LM431AIM/NOPB has a reference voltage (VREF) of 2.47 V to 2.52 V at 25°C, corresponding to ±1% initial tolerance. This specification is guaranteed per TI's SNVS020H datasheet Section 6.5, and applies specifically to the 'A' grade variant denoted in the part number suffix 'AIM'.
Can LM431AIM/NOPB replace a standard Zener diode in existing designs?
Yes, LM431AIM/NOPB can directly replace many Zener diodes in shunt regulation applications. It requires only two external resistors to set output voltage and provides superior temperature stability (50 ppm/°C), lower dynamic impedance (0.75 Ω), and programmability from 2.5 V to 36 V - all while maintaining pin-compatible implementation in SOIC-8 layouts originally designed for discrete Zeners with added bias networks.
What is the minimum cathode current required for regulation in LM431AIM/NOPB?
The LM431AIM/NOPB requires a minimum cathode current (IZ(MIN)) of 0.4 mA to 1 mA to maintain regulation, as specified in Section 6.5 of the SNVS020H datasheet. This value varies with temperature and must be ensured across worst-case conditions - including lowest input voltage and highest load current - to prevent dropout in feedback loops.
Does LM431AIM/NOPB support operation above 36 V cathode voltage?
No, LM431AIM/NOPB has an absolute maximum cathode voltage rating of 37 V, with recommended operation limited to 36 V. Exceeding this risks permanent damage per Section 6.1 Absolute Maximum Ratings. For >36 V applications, external clamping or series regulation must be added upstream of the LM431AIM/NOPB cathode.
How does the LM431AIM/NOPB reference input current affect resistor divider design?
The LM431AIM/NOPB reference input current (IREF) is 2–4 μA at 25°C and increases to ≤1.2 μA over temperature. This low bias current allows use of high-value feedback resistors (e.g., 100 kΩ–1 MΩ), minimizing power loss while ensuring divider output impedance stays well below 10 kΩ to avoid regulation error - a key constraint confirmed in Figure 7 and Section 9.2.1.2 of the datasheet.
LM431AIM/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Series:
- -
- Packaging:
- Tube
- 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
LM431AIM/NOPB FAQ
1.How can I place an order for LM431AIM/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM431AIM/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 LM431AIM/NOPB reliable?
The price and inventory of LM431AIM/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM431AIM/NOPB is usually 5 days.
3.What payment methods are accepted for LM431AIM/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM431AIM/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM431AIM/NOPB?
LM431AIM/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM431AIM/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 LM431AIM/NOPB?
For technical support, including LM431AIM/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM431AIM/NOPB requirements.
6.How does Aetrix verify that LM431AIM/NOPB is sourced from the original manufacturer or authorized distributors?
All LM431AIM/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 LM431AIM/NOPB meets industry standards.
7.What is the process for return or replacement of LM431AIM/NOPB?
All LM431AIM/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM431AIM/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 LM431AIM/NOPB part is unused and in its original packaging.
Return procedure for LM431AIM/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM431AIM/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…
