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Texas Instruments LM431BCM/NOPB
- Part No.:
- LM431BCM/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- Voltage Reference
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LM431BCM/NOPB.pdf
- Description:
- IC VREF SHUNT ADJ 1% 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,438
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Product details
Overview
LM431BCM/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 for regulation, and SOIC-8 package. It replaces Zener diodes in voltage monitoring, current sink/source, and linear/switching power supply feedback circuits.
For engineers reviewing the LM431BCM/NOPB datasheet, LM431BCM/NOPB pinout, LM431BCM/NOPB application, or LM431BCM/NOPB equivalent, this page delivers verified electrical specs, validated SOIC-8 pin functions, confirmed thermal and stability behavior, and real-world implementation guidance for precision shunt regulation design.
Technical Context
The LM431BCM/NOPB operates as a two-terminal programmable Zener with internal bandgap reference and high-gain comparator driving an NPN output stage. Its reference input (pin 8) senses external resistor-divider voltage, while cathode (pin 1) sinks current to maintain regulated output voltage between 2.5 V and 36 V.
It functions in closed-loop shunt mode with 1–100 mA cathode current range and supports open-loop comparator use. Temperature-compensated reference ensures stable operation from 0°C to 70°C, with average TC of 50 ppm/°C and thermal hysteresis typical under 10 mV after cycling.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reference voltage (VREF) | 2.485–2.51 V at 10 mA - defines base regulation point; sets minimum output voltage when used with external resistors |
| Reference voltage deviation | ±17 mV over full temperature range - determines worst-case output voltage drift in precision applications |
| Dynamic output impedance | 0.5 Ω at DC - enables tight load regulation and low noise in feedback loops |
| Minimum cathode current | 0.4–1 mA - minimum shunt current required to maintain regulation; dictates series resistor sizing |
| Cathode voltage range | 2.5 V to 36 V - maximum programmable output voltage; limited by absolute max rating of 37 V |
| Operating temperature | 0°C to 70°C - commercial-grade specification; distinct from industrial −40°C to 85°C variants |
| Package | SOIC-8 (4.90 mm × 3.91 mm) - surface-mount, 8-pin body with pins 2,3,6,7 as Anode, pin 1 as Cathode, pin 8 as Reference |
Pinout & Package
LM431BCM/NOPB uses an 8-pin SOIC (D) package with 4.90 mm × 3.91 mm body size, RoHS-compliant matte tin lead finish, and MSL Level-1 rating. Pin 4 and pin 5 are internally unconnected (NC).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (pins 2,3,6,7) | Common ground reference node | Internally tied together; must be connected to system ground for proper regulation |
| Cathode (pin 1) | Output voltage node / shunt current sink | Delivers regulated voltage; sinks all excess current not drawn by load |
| Reference (pin 8) | Feedback input for voltage divider network | Senses divided output voltage; triggers regulation when input reaches 2.5 V threshold |
| NC (pins 4,5) | No internal connection | Must remain unconnected; floating or tied to ground has no functional effect |
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 dynamic output impedance | 0.5 Ω at DC - maintains stable output under varying load conditions without external compensation |
| Fast turn-on response | Sub-microsecond transition from OFF to regulation - supports transient-sensitive feedback paths |
| Temperature-compensated reference | Average TC = 50 ppm/°C over 0°C–70°C - ensures <±0.35% output drift across operating range |
| Low-output noise | Typical broadband noise <10 µVRMS - suitable for precision analog sensing and reference applications |
Applications
| Adjustable Power Supply Feedback | Voltage Monitoring Circuit |
|---|---|
|
Use Scenario: Regulating output of isolated flyback or forward converter via optocoupler feedback loop. IC Role / Device Role / Timing Role: Shunt regulator providing precise 2.5 V reference to drive optocoupler LED; sets secondary-side error signal. Use Value: Enables ±1% output accuracy across line/load/temperature; replaces discrete Zener + transistor with single IC and two resistors. |
Use Scenario: Detecting overvoltage condition on a 12 V automotive rail before ECU damage occurs. IC Role / Device Role / Timing Role: Precision comparator with programmable trip point; triggers shutdown circuit when voltage exceeds 12.5 V. Use Value: Achieves 50 mV trip accuracy at 12.5 V using 1% resistors; avoids false triggers due to thermal drift. |
| Constant Current Sink | Zener Diode Replacement |
|
Use Scenario: Biasing high-brightness LED string with stable 350 mA current in industrial lighting. IC Role / Device Role / Timing Role: Shunt-based current regulator where cathode connects to LED anode and anode to ground. Use Value: Maintains ±2% current accuracy over 0°C–70°C; eliminates thermal runaway risk of standard Zeners. |
Use Scenario: Replacing 5.1 V Zener in legacy power supply feedback path requiring tighter tolerance. IC Role / Device Role / Timing Role: Programmable shunt reference configured for fixed 5.1 V output using R1/R2 = 1.04. Use Value: Delivers 0.5% initial accuracy vs. ±5% for standard Zener; reduces calibration effort in production test. |
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 | Same 2.5 V reference, but 0.2 Ω dynamic impedance and −0.5 V to 37 V cathode rating; SOIC-8, commercial temp | Higher precision and lower impedance support tighter regulation in high-performance SMPS feedback | Select TL431ACDR when <0.3% output tolerance or sub-0.3 Ω impedance is required; verify layout stability per TI SNVA262 |
| LM431CIM/NOPB | Identical electrical specs but −40°C to 85°C operating range; same SOIC-8 package and pinout | Required for industrial environments where ambient exceeds 70°C or dips below 0°C | Choose LM431CIM/NOPB for extended temperature deployments; no PCB changes needed if thermal margin allows |
Compared with LM431BCM/NOPB, TL431ACDR offers superior dynamic impedance for demanding feedback loops, while LM431CIM/NOPB extends operational range without altering circuit design-making both viable alternatives depending on thermal or precision requirements.
Availability
LM431BCM/NOPB is available at Aetrix Electronics and suitable for adjustable power supplies, voltage monitors, current sink circuits, and Zener replacement designs requiring stable component supply across commercial temperature range.
Supply support for LM431BCM/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 consumer markets since 1930.
The LM431 product line was designed as a drop-in upgrade to discrete Zener+transistor shunt regulators, targeting cost-sensitive yet precision-critical applications in power management and voltage reference systems.
FAQ
What is the reference voltage tolerance of LM431BCM/NOPB?
The LM431BCM/NOPB has a reference voltage (VREF) of 2.485 V to 2.51 V at 10 mA and 25°C, corresponding to ±0.6% initial tolerance. Over the full 0°C to 70°C operating range, VREF deviates by up to ±17 mV, which represents ±0.68% worst-case drift relative to nominal 2.5 V. This is specified in Section 6.5 of the SNVS020H datasheet.
Can LM431BCM/NOPB replace a standard 5.1 V Zener diode directly?
Yes, LM431BCM/NOPB can replace a 5.1 V Zener by configuring external resistors R1 and R2 such that VO = VREF × (1 + R1/R2) = 5.1 V. With VREF ≈ 2.5 V, R1/R2 ≈ 1.04. Unlike a Zener, the LM431BCM/NOPB requires a minimum 1 mA cathode current to regulate, so the series resistor must be sized accordingly. No additional active components are needed.
What is the maximum cathode voltage rating for LM431BCM/NOPB?
The absolute maximum cathode voltage for LM431BCM/NOPB is 37 V, as stated in Section 6.1 of the datasheet. The recommended operating range extends from VREF (2.5 V) up to 36 V. Exceeding 37 V risks permanent damage. This limit applies regardless of current level or duration.
Does LM431BCM/NOPB require an input bypass capacitor?
No, LM431BCM/NOPB does not require an input bypass capacitor for basic regulation. However, TI recommends a 0.1 µF ceramic capacitor placed physically close to the cathode pin to reduce noise coupling and improve stability in noisy environments or high-frequency switching applications, per Section 10 of the datasheet.
How does the LM431BCM/NOPB pinout differ from the TO-92 version?
LM431BCM/NOPB uses an 8-pin SOIC package with Anode on pins 2,3,6,7; Cathode on pin 1; Reference on pin 8; and NC on pins 4,5. In contrast, the TO-92 version (e.g., LM431BCZ/NOPB) has only three pins: Cathode (1), Anode (2), Reference (3). The SOIC layout supports higher power dissipation and better thermal performance but requires different PCB footprint and routing.
LM431BCM/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:
- ±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:
- 8-SOIC
LM431BCM/NOPB FAQ
1.How can I place an order for LM431BCM/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM431BCM/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 LM431BCM/NOPB reliable?
The price and inventory of LM431BCM/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM431BCM/NOPB is usually 5 days.
3.What payment methods are accepted for LM431BCM/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM431BCM/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM431BCM/NOPB?
LM431BCM/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM431BCM/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 LM431BCM/NOPB?
For technical support, including LM431BCM/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM431BCM/NOPB requirements.
6.How does Aetrix verify that LM431BCM/NOPB is sourced from the original manufacturer or authorized distributors?
All LM431BCM/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 LM431BCM/NOPB meets industry standards.
7.What is the process for return or replacement of LM431BCM/NOPB?
All LM431BCM/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM431BCM/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 LM431BCM/NOPB part is unused and in its original packaging.
Return procedure for LM431BCM/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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