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Texas Instruments LM431BCZ/NOPB
- Part No.:
- LM431BCZ/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- Voltage Reference
- Package:
- TO-226-3, TO-92-3 (TO-226AA)
- Datasheet:
-
LM431BCZ/NOPB.pdf
- Description:
- IC VREF SHUNT ADJ 1% TO92-3
- Quantity:
- Payment:
- Shipping:
Inventory:910
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Product details
Overview
LM431BCZ/NOPB from Texas Instruments is a 3-terminal adjustable precision shunt regulator with 2.5 V nominal reference voltage, ±10 mV initial tolerance (B-grade), 50 ppm/°C average temperature coefficient, and stable operation from −40°C to +85°C. It functions as a programmable Zener replacement in feedback loops of linear and switching power supplies, delivering precise voltage regulation via external resistor divider.
For engineers reviewing the LM431BCZ/NOPB datasheet, LM431BCZ/NOPB pinout, LM431BCZ/NOPB application, or LM431BCZ/NOPB equivalent, this page provides verified package mapping (TO-92, 3-pin), confirmed thermal performance (162.4°C/W RθJA), validated minimum cathode current (0.4 mA), and real-world design context for voltage monitoring and current sink circuits.
Technical Context
The LM431BCZ/NOPB implements an internal bandgap reference and high-gain comparator driving an NPN output stage, enabling sharp turn-on and low dynamic impedance (0.5 Ω typical). Its reference input draws only 2–4 μA, minimizing divider loading error while supporting programmable output voltages from 2.5 V to 36 V.
It operates in closed-loop shunt mode where the reference pin senses a fraction of cathode voltage via resistive divider; regulation is maintained when cathode current stays within 0.4–100 mA. Thermal hysteresis is characterized at <10 mV after cycling between 0°C and 70°C, confirming stability for precision references.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reference voltage (VREF) | 2.485–2.51 V at 10 mA - defines base accuracy for programmable output setting |
| Initial tolerance | ±10 mV (B-grade) - enables tight output voltage control without trimming |
| Average tempco | 50 ppm/°C - ensures ≤1.75 mV drift over −40°C to +85°C operating range |
| Dynamic output impedance | 0.5 Ω typical - maintains low output noise and fast transient response under load |
| Min cathode current (IZ(MIN)) | 0.4 mA - sets minimum bias requirement for reliable regulation onset |
| Max cathode current | 100 mA - determines maximum shunt power handling (2.5 W at 36 V) |
| OFF-state current (IZ(OFF)) | 0.3–1 μA at 36 V - ensures negligible leakage when disabled or unpowered |
Pinout & Package
LM431BCZ/NOPB uses the TO-92 package (3-pin, 4.30 mm × 4.30 mm body), with leads arranged in straight-line configuration. The package supports through-hole mounting and has a thermal resistance of 162.4°C/W (RθJA) at 25°C ambient.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (Pin 3) | Output return path | Internally connected to emitter of output transistor; typically grounded or tied to lowest system potential |
| Cathode (Pin 1) | Shunt current output / regulated voltage node | Carries total load + shunt current; voltage at this pin is the regulated output (VZ) |
| Reference (Pin 2) | Feedback sense input | High-impedance (2–4 μA) input that triggers regulation when voltage reaches VREF; connects to resistor divider midpoint |
Key Features
| Feature | Design Value |
|---|---|
| Programmable output voltage | 2.5 V to 36 V using two external resistors - eliminates need for multiple fixed Zener diodes |
| Low-reference input current | 2–4 μA typical - reduces divider power loss and improves accuracy with high-value resistors |
| Fast turn-on response | Sub-microsecond activation - supports dynamic load regulation and protection circuitry |
| Low-output noise | Typical 20 μVrms - suitable for sensitive analog references and measurement systems |
| Temperature-compensated reference | Stable over full −40°C to +85°C range - no external compensation required |
Applications
| Adjustable Power Supply Feedback | Voltage Monitoring Circuit |
|---|---|
Use Scenario: Regulating output of isolated flyback or buck converter by sensing secondary-side voltage via optocoupler feedback network. IC Role / Device Role / Timing Role: Precision shunt reference providing stable 2.5 V threshold to drive optocoupler LED, closing control loop with <1% output error. Use Value: Enables accurate, temperature-stable regulation without secondary-side LDO; supports wide input/output ranges up to 36 V. |
Use Scenario: Detecting overvoltage condition on a 12 V rail to trigger shutdown or alert logic in industrial PLC I/O modules. IC Role / Device Role / Timing Role: High-impedance voltage comparator with built-in reference, comparing scaled rail voltage against VREF via resistor divider. Use Value: Eliminates need for external reference IC and comparator; achieves ±1% trip point accuracy across temperature with minimal BOM count. |
| Constant Current Sink | Zener Diode Replacement |
Use Scenario: Providing stable 20 mA bias current to LED string or sensor in battery-powered IoT node. IC Role / Device Role / Timing Role: Shunt-regulated current source where cathode connects to constant-voltage rail and anode sinks current through load to ground. Use Value: Delivers <1% current stability over temperature and supply variation; replaces discrete transistor-current-source designs with single component. |
Use Scenario: Replacing 3.3 V Zener diode in microcontroller reset circuit requiring tighter voltage tolerance and lower leakage. IC Role / Device Role / Timing Role: Adjustable shunt regulator configured as fixed 3.3 V reference using 1% resistors, with 0.3 μA OFF-state current. Use Value: Reduces leakage by >10× vs. standard Zener; improves reset threshold accuracy and long-term reliability in low-power systems. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar shunt regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TL431ACZ | Higher initial tolerance (±2%), wider VREF range (2.495 V), same TO-92 package and pinout | Suitable for cost-sensitive applications where ±2% output accuracy is acceptable | Select TL431ACZ when tighter initial tolerance is not required and lower unit cost is prioritized |
| LM431AIM3X/NOPB | SOT-23-3 package, −40°C to +85°C rating, same B-grade electrical specs, smaller footprint | Preferred for space-constrained PCBs where TO-92 mounting is impractical | Choose LM431AIM3X/NOPB when board area is limited and reflow-compatible SMT assembly is used |
Compared with TL431ACZ and LM431AIM3X/NOPB, LM431BCZ/NOPB offers superior initial accuracy (±10 mV vs. ±20 mV) in the TO-92 through-hole package, making it optimal for legacy designs, prototyping, and applications requiring proven mechanical robustness and serviceability.
Availability
LM431BCZ/NOPB is available at Aetrix Electronics and suitable for adjustable power supplies, voltage monitors, current sink circuits, and Zener replacement applications requiring stable component supply and long-term manufacturability.
Supply support for LM431BCZ/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 and embedded processing technologies, with decades of experience in precision reference and power management ICs.
The LM431 product line was designed for cost-effective, high-accuracy shunt regulation in power conversion, voltage supervision, and current-source applications-targeting industrial, automotive, and consumer systems requiring robust, temperature-stable references.
FAQ
What is the reference voltage tolerance of LM431BCZ/NOPB?
The LM431BCZ/NOPB has a B-grade reference voltage tolerance of ±10 mV (2.485 V to 2.51 V) at 10 mA and 25°C. This corresponds to ±0.4% accuracy relative to the nominal 2.5 V reference, and is confirmed in the Electrical Characteristics table of the SNVS020H datasheet. The LM431BCZ/NOPB maintains this specification across its full operating temperature range.
Can LM431BCZ/NOPB be used as a standalone voltage reference without external resistors?
Yes, LM431BCZ/NOPB can operate as a 2.5 V shunt reference by connecting the reference pin directly to the cathode (i.e., R1 = 0, R2 = open), resulting in VZ = VREF. In this configuration, it delivers 2.5 V ±10 mV with 50 ppm/°C drift and requires ≥0.4 mA cathode current. The LM431BCZ/NOPB does not require additional components for basic reference operation.
What is the maximum cathode voltage supported by LM431BCZ/NOPB?
The absolute maximum cathode voltage for LM431BCZ/NOPB is 37 V, as specified in Section 6.1 of the SNVS020H datasheet. For reliable continuous operation, the recommended maximum cathode voltage is 36 V. Exceeding 37 V risks permanent device damage, regardless of current level.
Does LM431BCZ/NOPB require an input bypass capacitor?
No, LM431BCZ/NOPB does not require an input bypass capacitor for basic regulation. However, TI recommends adding a 0.1 µF ceramic capacitor close to the cathode pin if input noise exceeds 10 mVpp or if the application involves fast transients-this improves noise immunity and prevents oscillation. The LM431BCZ/NOPB remains stable without it under clean DC conditions.
How does LM431BCZ/NOPB differ from LM431ACZ/NOPB?
The LM431BCZ/NOPB (B-grade) offers tighter reference voltage tolerance (±10 mV) versus LM431ACZ/NOPB (A-grade, ±25 mV), while sharing identical TO-92 packaging, pinout, temperature range (0°C to 70°C), and all other electrical characteristics. Both use the same die and process; the difference is solely in post-package test screening. The LM431BCZ/NOPB is selected for higher-accuracy applications where tighter initial VREF is critical.
LM431BCZ/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Package/Case:
- TO-226-3, TO-92-3 (TO-226AA)
- Series:
- -
- Packaging:
- Bulk
- 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:
- Through Hole
- Supplier Device Package:
- TO-92-3
LM431BCZ/NOPB FAQ
1.How can I place an order for LM431BCZ/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM431BCZ/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 LM431BCZ/NOPB reliable?
The price and inventory of LM431BCZ/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM431BCZ/NOPB is usually 5 days.
3.What payment methods are accepted for LM431BCZ/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM431BCZ/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM431BCZ/NOPB?
LM431BCZ/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM431BCZ/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 LM431BCZ/NOPB?
For technical support, including LM431BCZ/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM431BCZ/NOPB requirements.
6.How does Aetrix verify that LM431BCZ/NOPB is sourced from the original manufacturer or authorized distributors?
All LM431BCZ/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 LM431BCZ/NOPB meets industry standards.
7.What is the process for return or replacement of LM431BCZ/NOPB?
All LM431BCZ/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM431BCZ/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 LM431BCZ/NOPB part is unused and in its original packaging.
Return procedure for LM431BCZ/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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