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Texas Instruments LM431ACM3/NOPB
- Part No.:
- LM431ACM3/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- Voltage Reference
- Package:
- TO-236-3, SC-59, SOT-23-3
- Datasheet:
-
LM431ACM3/NOPB.pdf
- Description:
- IC VREF SHUNT ADJ 2.2% SOT23-3
- Quantity:
- Payment:
- Shipping:
Inventory:9,721
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Product details
Overview
LM431ACM3/NOPB from Texas Instruments is a precision adjustable shunt regulator in SOT-23-3 package, featuring 2.495 V nominal reference voltage (VREF), ±17 mV max reference deviation over 0°C to 70°C, 0.5 Ω typical dynamic output impedance, and 1 mA minimum cathode current for regulation - used in feedback loops of linear/switching power supplies and voltage monitoring circuits.
For engineers reviewing the LM431ACM3/NOPB datasheet, LM431ACM3/NOPB pinout, LM431ACM3/NOPB application, or LM431ACM3/NOPB equivalent, this page delivers verified electrical specs, validated SOT-23 pin mapping, real-world use cases in overvoltage protection and current sinking, and two confirmed alternative parts with documented functional differences.
Technical Context
The LM431ACM3/NOPB operates as a 3-terminal programmable shunt regulator: its reference pin senses a divided fraction of cathode voltage, triggering internal amplification to adjust shunt current and maintain precise output voltage. It functions in closed-loop mode with external resistor dividers or open-loop comparator mode with independent reference biasing.
Its architecture ensures stable regulation across 2.5 V–36 V output range using only two external resistors, with fast turn-on response and low-output noise enabling replacement of discrete Zener diodes in precision applications requiring temperature-stable references.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VREF (nom) | 2.495 V - sets base reference for programmable output voltage calculation |
| VREF deviation | ±17 mV over 0°C to 70°C - defines worst-case output accuracy drift in commercial temp range |
| Dynamic impedance | 0.5 Ω typical - determines output voltage stability under load transients |
| Min cathode current | 1 mA - minimum shunt current required to maintain regulation |
| Max cathode voltage | 36 V - absolute upper limit for cathode-to-anode voltage in operation |
| Reference input current | 2–4 μA - low bias current enabling high-resistance feedback networks |
| Temp coefficient | 50 ppm/°C average - quantifies reference voltage drift per degree Celsius |
Pinout & Package
SOT-23-3 package (2.92 mm × 1.30 mm body), surface-mount, lead-free (Sn finish), moisture sensitivity level 1 (260°C peak reflow).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode | Output / Shunt node | Connected to regulated voltage rail; sinks current to ground to maintain setpoint |
| Anode | Ground reference | Typically tied to system ground; completes shunt current path |
| Reference | Feedback input | Monitors voltage divider output; triggers regulation when ≈2.495 V is reached |
Key Features
| Feature | Design Value |
|---|---|
| Programmable output voltage | 2.5 V to 36 V via external resistor divider - enables single BOM part across multiple voltage rails |
| Low dynamic output impedance | 0.5 Ω typical - minimizes output voltage sag during load steps without added compensation |
| Fast turn-on response | Enables stable startup in switching regulators and crowbar protection circuits |
| Temperature-compensated reference | 50 ppm/°C avg TC and ±17 mV VREF deviation over 0°C–70°C - ensures accuracy without external calibration |
| Space-saving SOT-23 package | 2.92 mm × 1.30 mm footprint - reduces PCB area vs TO-92 or SOIC alternatives in space-constrained designs |
Applications
| Adjustable Power Supply Feedback | Voltage Monitoring |
|---|---|
Use Scenario: Regulating output of isolated flyback or buck converter by sensing secondary-side voltage through optocoupler feedback network. IC Role / Device Role / Timing Role: Precision shunt reference providing stable 2.495 V threshold for error amplifier comparison. Use Value: Enables tight output tolerance (±1%) without trimming, leveraging low VREF drift and high PSRR. |
Use Scenario: Detecting overvoltage condition on 12 V automotive rail to trigger shutdown before downstream damage occurs. IC Role / Device Role / Timing Role: Programmable threshold comparator with hysteresis via external resistor network. Use Value: Replaces discrete Zener + transistor circuit with single-component solution and guaranteed 50 ppm/°C stability. |
| Current Sink Circuit | Zener Diode Replacement |
Use Scenario: Providing constant 10 mA bias current to photodiode amplifier in optical sensor module. IC Role / Device Role / Timing Role: Adjustable current sink configured with fixed cathode voltage and series resistor. Use Value: Delivers stable current over temperature (±1% variation) due to low-reference TC and minimal dynamic impedance. |
Use Scenario: Replacing 3.3 V Zener diode in low-power microcontroller reset circuit where tighter voltage tolerance is required. IC Role / Device Role / Timing Role: Precision shunt reference operating at 3.3 V with R1/R2 = 0.32× ratio. Use Value: Achieves ±1.5% output accuracy vs ±5% for standard Zener, reducing false resets in industrial environments. |
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 | Same 2.495 V VREF, but 0.2 Ω lower dynamic impedance (0.3 Ω typ); higher max cathode current (100 mA vs 150 mA absolute max) | Preferred in high-precision LDO feedback where sub-0.5 Ω impedance is critical | Select TL431ACDBVR if lower output impedance and tighter VREF tolerance (±0.5%) are required; same SOT-23-3 footprint. |
| AS431ARTDT-33 | 2.5 V nominal VREF, ±25 mV deviation over 0°C–70°C, 1.2 Ω dynamic impedance, 2.5 μA reference current | Better suited for cost-sensitive consumer applications where ±2% output accuracy is acceptable | Choose AS431ARTDT-33 for budget designs needing basic shunt regulation without premium stability specs. |
Compared with LM431ACM3/NOPB, TL431ACDBVR offers superior impedance and tighter VREF tolerance for high-accuracy feedback, while AS431ARTDT-33 trades performance for cost in less demanding voltage-monitoring roles.
Availability
LM431ACM3/NOPB is available at Aetrix Electronics and suitable for adjustable power supply feedback, voltage monitoring, current sink circuits, and Zener diode replacement applications requiring stable component supply and commercial-temperature-grade precision.
Supply support for LM431ACM3/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 drop-in upgrade to discrete Zener-based shunt regulators, targeting applications needing programmable, temperature-stable voltage references in compact packages.
FAQ
What is the reference voltage tolerance of LM431ACM3/NOPB over temperature?
The LM431ACM3/NOPB has a maximum reference voltage deviation of ±17 mV over the full 0°C to 70°C operating range, corresponding to ±0.68% of the nominal 2.495 V VREF. This specification is explicitly defined in the Electrical Characteristics table of the SNVS020H datasheet under parameter VDEV, measured at TA = full range.
Can LM431ACM3/NOPB be used as a comparator?
Yes, LM431ACM3/NOPB can operate in open-loop comparator mode: apply a voltage to the reference pin while holding cathode at fixed potential. When reference voltage exceeds 2.495 V, the device turns on and sinks current. This behavior is documented in Section 8.4 (Device Functional Modes) of the datasheet.
What is the minimum cathode current required for regulation in LM431ACM3/NOPB?
The LM431ACM3/NOPB requires a minimum cathode current of 1 mA to maintain regulation, as specified in the Electrical Characteristics table under IZ(MIN). Below this threshold, output voltage may deviate beyond tolerance limits, especially near temperature extremes.
Does LM431ACM3/NOPB support output voltages below 2.5 V?
No, LM431ACM3/NOPB cannot regulate output voltages below 2.5 V. Its internal reference voltage is fixed at 2.495 V (nominal), and the output equation VO = VREF × (1 + R1/R2) yields a minimum VO equal to VREF when R1 = 0 - making 2.495 V the practical lower limit.
What package type is LM431ACM3/NOPB supplied in?
LM431ACM3/NOPB is supplied in the SOT-23-3 package (DBZ), with dimensions 2.92 mm × 1.30 mm, RoHS-compliant Sn lead finish, and moisture sensitivity level 1 (MSL-1) rated for peak reflow at 260°C - confirmed in TI's Package Option Addendum for orderable part number LM431ACM3/NOPB.
LM431ACM3/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:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-23-3
LM431ACM3/NOPB FAQ
1.How can I place an order for LM431ACM3/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM431ACM3/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 LM431ACM3/NOPB reliable?
The price and inventory of LM431ACM3/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM431ACM3/NOPB is usually 5 days.
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We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM431ACM3/NOPB transactions.
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4.How is shipping managed for LM431ACM3/NOPB?
LM431ACM3/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM431ACM3/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 LM431ACM3/NOPB?
For technical support, including LM431ACM3/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM431ACM3/NOPB requirements.
6.How does Aetrix verify that LM431ACM3/NOPB is sourced from the original manufacturer or authorized distributors?
All LM431ACM3/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 LM431ACM3/NOPB meets industry standards.
7.What is the process for return or replacement of LM431ACM3/NOPB?
All LM431ACM3/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM431ACM3/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 LM431ACM3/NOPB part is unused and in its original packaging.
Return procedure for LM431ACM3/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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