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Texas Instruments LM431BCM3/NOPB
- Part No.:
- LM431BCM3/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- Voltage Reference
- Package:
- TO-236-3, SC-59, SOT-23-3
- Datasheet:
-
LM431BCM3/NOPB.pdf
- Description:
- IC VREF SHUNT ADJ 1% SOT23-3
- Quantity:
- Payment:
- Shipping:
Inventory:13,824
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Product details
Overview
LM431BCM3/NOPB from Texas Instruments is a 3-terminal adjustable precision shunt regulator with 2.5 V reference voltage, ±17 mV reference deviation over temperature, 0.5 Ω dynamic output impedance, 1 mA minimum cathode current, and 100 mA maximum cathode current. It operates as a programmable Zener replacement in feedback loops of linear and switching power supplies.
For engineers reviewing the LM431BCM3/NOPB datasheet, LM431BCM3/NOPB pinout, LM431BCM3/NOPB application, or LM431BCM3/NOPB equivalent, this page delivers verified electrical specs, SOT-23-3 package mapping, thermal derating guidance, and real-world use cases for voltage monitoring, current sinking, and precision reference design.
Technical Context
The LM431BCM3/NOPB implements an internal bandgap reference and high-gain comparator driving a NPN output transistor to regulate cathode voltage via shunt current control. Its reference input draws only 2–4 μA, enabling low-power bias networks.
It functions in closed-loop mode with external resistor dividers to set output voltages from 2.5 V to 36 V, and supports open-loop comparator operation when the reference pin is driven externally. Thermal hysteresis is characterized at 25°C after cycling between 0°C and 70°C.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reference voltage (VREF) | 2.485–2.51 V at 25°C - defines minimum programmable output and sets accuracy baseline for resistor-divider designs |
| Reference voltage deviation | ±17 mV over full temperature range - determines worst-case output error without trimming |
| Dynamic output impedance | 0.5 Ω at DC - enables stable regulation under fast load transients when used with proper bypassing |
| Minimum cathode current | 0.4–1 mA - sets lower bound for RS resistor sizing to maintain regulation during light-load conditions |
| Maximum cathode current | 150 mA absolute max, 100 mA recommended operating limit - defines upper thermal and reliability boundary for continuous operation |
| Temperature coefficient | Average 50 ppm/°C - quantifies drift per degree Celsius, critical for precision reference stability across ambient shifts |
| ESD rating (HBM) | ±2500 V - informs handling requirements and board-level protection needs during assembly |
Pinout & Package
SOT-23-3 package (DBZ), 2.92 mm × 1.30 mm body size, single-row 3-pin surface-mount configuration with gull-wing leads. RoHS-compliant matte tin lead finish, MSL Level-1, peak reflow 260°C.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Output return path | Internally connected to emitter of output transistor; typically grounded or tied to lowest system potential |
| Cathode | Regulated output node | Shunt current sink point; voltage at this pin is controlled by reference divider; connects to supply rail or feedback node |
| Reference | Feedback input | High-impedance input (2–4 μA) that senses divided output voltage; sets regulation threshold via resistor ratio |
Key Features
| Feature | Design Value |
|---|---|
| Adjustable output voltage range | 2.5 V to 36 V - achieved with two external resistors, eliminating need for multiple fixed-voltage Zeners |
| Fast turn-on response | Enables use in crowbar circuits and overvoltage protection where rapid clamping is required |
| Low-output noise | Supports clean reference generation in ADC/DAC biasing and sensor excitation without added filtering |
| Temperature-compensated operation | Stable performance across –40°C to +85°C industrial range without external compensation components |
| Space-saving SOT-23 package | Reduces PCB area by >70% vs TO-92; compatible with standard pick-and-place and reflow processes |
Applications
| Switch-Mode Power Supply Feedback | Voltage Monitoring Circuit |
|---|---|
Use Scenario: Secondary-side voltage sensing in isolated flyback converters using optocoupler feedback loop. IC Role / Device Role / Timing Role: Adjustable shunt regulator providing precise 2.5 V reference to drive optocoupler LED, enabling accurate output voltage regulation. Use Value: Enables ±1% output tolerance across line/load/temperature without trimming; replaces discrete Zener + transistor solutions. |
Use Scenario: Undervoltage lockout (UVLO) and overvoltage detection in battery-powered microcontroller systems. IC Role / Device Role / Timing Role: Precision comparator with programmable threshold, configured with resistor divider on reference pin. Use Value: Detects 3.3 V rail drop below 3.0 V or rise above 3.6 V with <±15 mV hysteresis, preventing brownout resets. |
| Constant Current Sink | Zener Diode Replacement |
Use Scenario: LED biasing in automotive interior lighting with thermal drift compensation. IC Role / Device Role / Timing Role: Shunt regulator configured as two-terminal current source, sinking fixed current independent of supply variation. Use Value: Delivers 20 mA ±2% over 9–16 V input range and –40°C to +85°C, eliminating LED brightness shift. |
Use Scenario: Replacing 3.3 V, 5.1 V, and 12 V Zener diodes in legacy analog power rails. IC Role / Device Role / Timing Role: Programmable shunt element with tighter tolerance (±1%), lower impedance (0.5 Ω), and lower leakage (<1 μA). Use Value: Reduces output ripple by 40% and improves load regulation by 3× compared to 5% tolerance Zeners. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar adjustable shunt regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TL431CDBVR | Same 2.5 V reference, but ±2% initial tolerance (vs ±0.5% for LM431BCM3/NOPB); 0.75 Ω dynamic impedance | Lower accuracy makes it suitable for non-critical feedback, not precision references or current sinks | Select when cost sensitivity outweighs 0.3% output error budget and thermal drift requirements |
| AS431ASTZTR-G1 | Pin-compatible SOT-23-3, 2.5 V reference, ±1% tolerance, 1.5 Ω dynamic impedance, higher 150 mA max cathode current | Higher impedance limits transient response; wider tolerance increases calibration burden in metrology designs | Prefer for high-current shunt applications where 0.5 Ω impedance is noncritical and extended current headroom is needed |
Compared with TL431CDBVR and AS431ASTZTR-G1, the LM431BCM3/NOPB offers the tightest reference tolerance (±0.5%), lowest dynamic impedance (0.5 Ω), and best temperature coefficient (50 ppm/°C), making it optimal for precision voltage references, low-drift current sources, and high-stability feedback loops.
Availability
LM431BCM3/NOPB is available at Aetrix Electronics and suitable for switch-mode power supply feedback, voltage monitoring, constant current sink, and Zener diode replacement applications requiring stable component supply across industrial temperature ranges and long production lifecycles.
Supply support for LM431BCM3/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 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, thermally demanding applications-targeting power supply feedback, voltage supervision, and programmable reference circuits across industrial, computing, and consumer systems.
FAQ
What is the reference voltage tolerance of LM431BCM3/NOPB?
The LM431BCM3/NOPB has a reference voltage (VREF) of 2.485 V to 2.51 V at 25°C, corresponding to ±0.5% initial tolerance. This is confirmed in Section 6.5 of the SNVS020H datasheet under "LM431B" grade specifications, and applies specifically to the BCM suffix variant.
Can LM431BCM3/NOPB replace a standard Zener diode directly?
Yes, the LM431BCM3/NOPB can directly replace many Zener diodes in shunt regulator configurations. Unlike passive Zeners, it requires only two external resistors to set voltage and provides superior accuracy (±0.5%), lower dynamic impedance (0.5 Ω), and guaranteed stability over –40°C to +85°C - all within the same SOT-23 footprint as many Zener packages.
What is the minimum cathode current required for regulation in LM431BCM3/NOPB?
The LM431BCM3/NOPB requires a minimum cathode current (IZ(MIN)) of 0.4 mA to 1 mA to maintain regulation, as specified in the Electrical Characteristics table (Section 6.5). This value is critical for selecting the series resistor (RS) to ensure stable operation under light-load or low-input-voltage conditions.
Does LM431BCM3/NOPB support operation above 36 V cathode voltage?
No. The absolute maximum cathode voltage for LM431BCM3/NOPB is 37 V, and the recommended operating maximum is 36 V (Section 6.3). Exceeding 36 V risks exceeding safe operating area limits and may cause premature failure; for higher-voltage applications, external clamping or series limiting is required.
How does the SOT-23 package affect thermal performance of LM431BCM3/NOPB?
The SOT-23 package for LM431BCM3/NOPB has a junction-to-ambient thermal resistance (RθJA) of 267.7°C/W (Section 6.4), meaning it dissipates significantly less power than SOIC or TO-92 variants. At 100 mA cathode current and 5 V drop, power dissipation reaches 0.5 W - requiring derating above 25°C ambient per the 2.2 mW/°C slope specified in the datasheet.
LM431BCM3/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:
- ±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/NOPB FAQ
1.How can I place an order for LM431BCM3/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM431BCM3/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 LM431BCM3/NOPB reliable?
The price and inventory of LM431BCM3/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM431BCM3/NOPB is usually 5 days.
3.What payment methods are accepted for LM431BCM3/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM431BCM3/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM431BCM3/NOPB?
LM431BCM3/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM431BCM3/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 LM431BCM3/NOPB?
For technical support, including LM431BCM3/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM431BCM3/NOPB requirements.
6.How does Aetrix verify that LM431BCM3/NOPB is sourced from the original manufacturer or authorized distributors?
All LM431BCM3/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 LM431BCM3/NOPB meets industry standards.
7.What is the process for return or replacement of LM431BCM3/NOPB?
All LM431BCM3/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM431BCM3/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 LM431BCM3/NOPB part is unused and in its original packaging.
Return procedure for LM431BCM3/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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