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Texas Instruments LM431BCM3
- Part No.:
- LM431BCM3
- Manufacturer:
- Texas Instruments
- Category:
- Voltage Reference
- Package:
- TO-236-3, SC-59, SOT-23-3
- Datasheet:
-
LM431BCM3.pdf
- Description:
- IC VREF SHUNT ADJ 1% SOT23-3
- Quantity:
- Payment:
- Shipping:
Inventory:4,641
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Product details
Overview
LM431BCM3 from Texas Instruments is a 3-terminal adjustable precision shunt regulator with 2.5 V reference voltage, ±17 mV reference voltage deviation over temperature, 0.5 Ω typical dynamic output impedance, and 1 mA minimum cathode current for regulation-used in voltage monitoring, current source circuits, and Zener diode replacement applications.
For engineers reviewing the LM431BCM3 datasheet, LM431BCM3 pinout, LM431BCM3 application, or LM431BCM3 equivalent, this page delivers verified electrical characteristics, SOT-23 package terminal mapping, thermal derating guidance, and real-world implementation constraints for linear power supply feedback, overvoltage protection, and precision current sinking.
Technical Context
The LM431BCM3 operates as a programmable shunt regulator by comparing its internal 2.5 V bandgap reference against an external resistor divider connected to the Reference pin; regulation is achieved by dynamically shunting cathode current to ground. Its closed-loop operation requires 1–100 mA cathode current and maintains stable output voltage across 0°C to 70°C.
It features low-output noise, fast turn-on response, and temperature-compensated reference voltage (50 ppm/°C average TC). The device supports open-loop comparator mode when the Reference pin is driven externally, enabling voltage threshold detection without additional components.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reference Voltage (VREF) | 2.485–2.51 V at 10 mA - defines minimum programmable output voltage and sets accuracy baseline for external resistor divider. |
| Reference Voltage Deviation | ±17 mV over full temperature range - limits worst-case output voltage error in precision feedback loops. |
| Dynamic Output Impedance | 0.5 Ω typical at DC - ensures minimal output voltage shift under load transients in shunt-regulated supplies. |
| Minimum Cathode Current | 0.4–1 mA - determines smallest usable series resistor value for reliable regulation at low input voltages. |
| Cathode Voltage Range | 2.5 V to 36 V - enables output programming from reference level up to near absolute maximum rating. |
| Reference Input Current | 2–4 μA - allows high-impedance feedback networks without significant divider current error. |
| ESD Rating (HBM) | ±2500 V - informs handling requirements during PCB assembly and bench testing. |
Pinout & Package
SOT-23 (DBZ) 3-pin surface-mount package: compact 2.92 mm × 1.30 mm footprint with gull-wing leads, moisture sensitivity level 1, RoHS-compliant tin-silver-copper finish.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode | Output / Shunt node | Connects to regulated voltage rail; sinks current to ground to maintain setpoint-must handle up to 100 mA continuous. |
| Anode | Ground reference | Common return path for internal reference and shunt circuitry; must be low-impedance connection to system ground. |
| Reference | Feedback input | High-impedance input sensing divided-down output voltage; drives internal comparator to control cathode conduction. |
Key Features
| Feature | Design Value |
|---|---|
| Adjustable output voltage | Programmable from 2.5 V to 36 V using two external resistors-enables single BOM part across multiple voltage rails. |
| Temperature-stable reference | Average 50 ppm/°C coefficient over 0°C to 70°C-reduces thermal drift in industrial monitoring and sensor excitation circuits. |
| Low dynamic output impedance | 0.5 Ω typical-maintains tight regulation during rapid load changes in switching supply feedback paths. |
| Fast turn-on response | Enables use in crowbar and overvoltage protection circuits where sub-microsecond reaction prevents downstream damage. |
| Space-saving SOT-23 package | 2.92 mm × 1.30 mm footprint-supports high-density PCB layouts in compact power modules and IoT edge devices. |
Applications
| Switching Power Supply Feedback | Voltage Monitoring |
|---|---|
Use Scenario: Secondary-side voltage sensing in isolated flyback converters to regulate output without optocoupler latency. IC Role / Device Role / Timing Role: Adjustable shunt regulator providing precise feedback reference to PWM controller via optocoupler LED drive. Use Value: Enables ±1% output accuracy over line/load/temperature while reducing component count versus fixed-reference + op-amp solutions. |
Use Scenario: Detection of undervoltage or overvoltage conditions on microcontroller I/O rails or battery inputs. IC Role / Device Role / Timing Role: Precision threshold comparator with programmable trip point, configured in open-loop mode. Use Value: Delivers 10 mV-level hysteresis control and stable trip points across temperature-critical for brownout reset reliability. |
| Current Source/Sink Circuit | Zener Diode Replacement |
Use Scenario: Constant-current bias for laser diodes or LED strings requiring <1% current stability. IC Role / Device Role / Timing Role: Shunt-based current regulator where cathode current equals load current plus reference current. Use Value: Achieves 0.05% current regulation drift over temperature-superior to discrete Zener + transistor approaches. |
Use Scenario: Replacing 2.5–36 V Zener diodes in legacy analog power supplies and test equipment. IC Role / Device Role / Timing Role: Drop-in functional replacement offering tighter tolerance, lower impedance, and guaranteed tempco. Use Value: Eliminates need for binning and improves long-term stability-especially valuable in field-deployed instrumentation. |
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%), 0.2 Ω dynamic impedance, 1 mA min cathode current, same SOT-23 package. | Higher initial accuracy but narrower operating temperature range (0°C to 70°C vs. LM431BCM3's identical range). | Select TL431ACDBVR when ±0.5% reference tolerance is required and board layout accommodates identical pinout. |
| AS431ARTDT | 2.5 V reference (±1%), 0.6 Ω dynamic impedance, 1 mA min cathode current, SOT-23 package with different marking. | Lower cost alternative with relaxed initial tolerance and higher dynamic impedance-suitable for non-critical biasing. | Choose AS431ARTDT for cost-sensitive consumer applications where 1% output tolerance is acceptable. |
Compared with TL431ACDBVR and AS431ARTDT, the LM431BCM3 offers balanced performance: tighter reference deviation (±17 mV) than AS431ARTDT and broader manufacturer support than TL431ACDBVR, making it optimal for industrial-grade feedback and monitoring where long-term stability matters.
Availability
LM431BCM3 is available at Aetrix Electronics and suitable for voltage monitoring, current source/sink circuits, and Zener diode replacement applications requiring stable component supply across industrial and commercial temperature ranges.
Supply support for LM431BCM3 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 product line was designed for high-accuracy shunt regulation in space-constrained, cost-sensitive systems-targeting power supply feedback, voltage supervision, and programmable current sources across industrial, computing, and communications equipment.
FAQ
What is the reference voltage tolerance of the LM431BCM3?
The LM431BCM3 has a reference voltage (VREF) of 2.485 V to 2.51 V at 10 mA and 25°C, corresponding to a ±1% initial tolerance. Its reference voltage deviation over the full 0°C to 70°C operating range is ±17 mV, which translates to approximately ±0.68% drift relative to nominal 2.5 V.
Can the LM431BCM3 replace a standard Zener diode directly?
Yes, the LM431BCM3 can directly replace Zener diodes rated between 2.5 V and 36 V. Unlike passive Zeners, it provides superior temperature stability (50 ppm/°C), lower dynamic impedance (0.5 Ω), and programmable output via external resistors-requiring only two added components for adjustable operation.
What is the minimum cathode current required for regulation in the LM431BCM3?
The LM431BCM3 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 collapses-designers must size the series resistor to guarantee ≥1 mA under worst-case conditions.
Does the LM431BCM3 support open-loop comparator operation?
Yes, the LM431BCM3 supports open-loop operation: when the Reference pin is driven externally (e.g., from a sensor or DAC), the device functions as a precision comparator with hysteresis controllable via feedback. This mode enables overvoltage/undervoltage detection without additional op-amps.
What thermal derating applies to the LM431BCM3 in SOT-23 package?
In the SOT-23 (DBZ) package, the LM431BCM3 has a thermal resistance of 267.7°C/W (junction-to-ambient). At ambient temperatures above 25°C, power dissipation must be derated at 2.2 mW/°C. For example, at 60°C ambient, max allowable power drops to 0.28 W − (35°C × 2.2 mW/°C) = 0.203 W.
LM431BCM3 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:
- Obsolete
- Reference Type:
- Shunt
- Output Type:
- Adjustable
- Voltage - Output (Min/Fixed):
- 2.495V
- Voltage - Output (Max):
- 37 V
- Current - Output:
- 100 mA
- Tolerance:
- ±1%
- 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
LM431BCM3 FAQ
1.How can I place an order for LM431BCM3 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM431BCM3 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 LM431BCM3 reliable?
The price and inventory of LM431BCM3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM431BCM3 is usually 5 days.
3.What payment methods are accepted for LM431BCM3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM431BCM3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM431BCM3?
LM431BCM3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM431BCM3 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 LM431BCM3?
For technical support, including LM431BCM3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM431BCM3 requirements.
6.How does Aetrix verify that LM431BCM3 is sourced from the original manufacturer or authorized distributors?
All LM431BCM3 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 LM431BCM3 meets industry standards.
7.What is the process for return or replacement of LM431BCM3?
All LM431BCM3 units undergo pre-shipment inspection (PSI). If there is an issue with LM431BCM3, 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 LM431BCM3 part is unused and in its original packaging.
Return procedure for LM431BCM3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM431BCM3 Tags
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TL431AIDBZR
Texas Instruments
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TL431BQDBZR
Texas Instruments
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AN431AN-ATRG1
Diodes Incorporated
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LM4040CYM3-2.5-TR
Microchip Technology
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LM4040CYM3-4.1-TR
Microchip Technology
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LM4040EIM3-2.5/NOPB
Texas Instruments
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AZ431LBNTR-G1
Diodes Incorporated
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LM4040D20IDBZR
Texas Instruments
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LM4041DIM3-ADJ/NOPB
Texas Instruments
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LM4040DIM3X-2.5/NOPB
Texas Instruments
-
LM4040DIM3-2.5/NOPB
Texas Instruments
-
AZ431LANTR-G1
Diodes Incorporated
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