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Texas Instruments LM431ACZ/NOPB
- Part No.:
- LM431ACZ/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- Voltage Reference
- Package:
- TO-226-3, TO-92-3 (TO-226AA)
- Datasheet:
-
LM431ACZ/NOPB.pdf
- Description:
- IC VREF SHUNT ADJ 2.2% TO92-3
- Quantity:
- Payment:
- Shipping:
Inventory:1,685
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Product details
Overview
LM431ACZ/NOPB from Texas Instruments is a 3-terminal adjustable precision shunt regulator with 2.47 V to 2.52 V reference voltage (VREF), ±17 mV max reference deviation over temperature, 0.5 Ω typical dynamic output impedance, and 1 mA minimum cathode current for regulation - used in voltage monitoring, current sink/source circuits, and as a Zener diode replacement in linear power supplies.
For engineers reviewing the LM431ACZ/NOPB datasheet, LM431ACZ/NOPB pinout, LM431ACZ/NOPB application, or LM431ACZ/NOPB equivalent, this page delivers verified technical context, TO-92 package mapping, real-world application cards, and two validated alternative parts with documented functional and thermal differences.
Technical Context
The LM431ACZ/NOPB operates as a precision shunt reference with an internal bandgap-derived 2.5 V reference, programmable via external resistor divider between cathode and reference pins. Its feedback architecture enables stable closed-loop regulation across 2.5 V–36 V output range when cathode current remains within 1–100 mA.
It features temperature-compensated internal circuitry ensuring ≤50 ppm/°C average temperature coefficient and low-output noise performance. The device supports both shunt regulator and open-loop comparator modes, with OFF-state cathode leakage <1 μA at 36 V and fast turnon response critical for protection circuits.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VREF | 2.47–2.52 V at 25°C; defines minimum programmable output voltage and sets accuracy baseline for external resistor network |
| VREF Deviation | ±17 mV over full operating temperature range (0°C to 70°C); determines worst-case output voltage drift in precision references |
| Dynamic Impedance (rZ) | 0.5 Ω typical at DC; ensures minimal output voltage variation under load transients in shunt regulation |
| Min Cathode Current (IZ(MIN)) | 1 mA; minimum shunt current required to maintain regulation - dictates minimum series resistor sizing |
| Max Cathode Current | 100 mA; absolute upper limit before thermal derating or failure - constrains power dissipation in TO-92 package |
| Reference Input Current | 2–4 μA; ultra-low bias current enabling high-resistance feedback networks without significant error |
| Temp Coefficient | 50 ppm/°C average; quantifies long-term stability of reference voltage across ambient temperature swings |
Pinout & Package
LM431ACZ/NOPB uses the TO-92 (LP) package: 4.30 mm × 4.30 mm body, 3-pin through-hole configuration with standard lead spacing. Thermal resistance RθJA = 162.4 °C/W at 25°C ambient; derates at 6.2 mW/°C above 25°C.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Output return path / ground reference | Internally connected to substrate; must be tied to system ground or lowest potential node in shunt configuration |
| Cathode | Shunt current output / regulated voltage node | Carries total load + shunt current; connects to output rail and series resistor (RS); voltage here equals programmed VOUT |
| Reference | Feedback input / precision voltage sense | Samples divided output voltage; draws only 2–4 μA - enables high-impedance resistor dividers without loading error |
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 |
| Temperature Compensation | Ensured stability over full 0°C to 70°C range - enables reliable operation in commercial-grade power supplies and monitors |
| Low Dynamic Output Impedance | 0.5 Ω typical - maintains tight voltage regulation during rapid load changes in current sink or crowbar applications |
| Fast Turnon Response | Enables use in overvoltage protection and delay timer circuits where sub-microsecond reaction is required |
| Low-Output Noise | Supports precision analog sensing and reference duties where ripple or broadband noise would degrade ADC accuracy |
Applications
| Adjustable Linear Power Supply | Voltage Monitoring Circuit |
|---|---|
Use Scenario: Regulating output of unregulated DC supply (e.g., rectified AC or battery-derived rail) to stable 5 V, 12 V, or custom voltage. IC Role / Device Role / Timing Role: Shunt regulator controlling output by sinking excess current through cathode to maintain precise voltage at feedback node. Use Value: Replaces discrete Zener + transistor combo with single IC offering tighter tolerance (±1%), lower temp drift, and simplified BOM. |
Use Scenario: Detecting overvoltage condition on a 24 V industrial bus to trigger shutdown or alarm before damage occurs. IC Role / Device Role / Timing Role: Precision reference comparing sensed bus voltage against threshold via resistor divider; drives comparator or optocoupler when exceeded. Use Value: Enables ±1% trip point accuracy over temperature - superior to generic Zener-based monitors with >5% tolerance drift. |
| Current Sink / Source | Crowbar Overvoltage Protection |
Use Scenario: Providing constant 10 mA bias current to photodiode amplifier or LED driver stage requiring stable current source. IC Role / Device Role / Timing Role: Configured as two-terminal current source with cathode as output and reference tied to cathode via resistor. Use Value: Delivers 0.1% current stability over temperature and line variations - outperforms discrete transistor current mirrors. |
Use Scenario: Protecting downstream 5 V logic from transient surges on a 12 V supply rail using SCR-triggered short-circuit activation. IC Role / Device Role / Timing Role: Precision voltage detector triggering SCR gate when cathode voltage exceeds safe threshold (e.g., 5.5 V). Use Value: Fast turnon and low-reference-drift ensure reliable, repeatable clamping at exact voltage - prevents false triggers or delayed response. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar adjustable shunt regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TL431ACZ | Same 2.495 V nominal VREF, but ±1% initial tolerance vs. LM431ACZ/NOPB's ±2%; higher 100 mA max cathode current rating; identical TO-92 package. | Preferred in high-accuracy feedback loops (e.g., isolated flyback PSUs) where tighter reference tolerance directly improves output regulation. | Select TL431ACZ when ±1% reference accuracy is required and layout allows same TO-92 footprint. |
| AS431ATZ | Pin-compatible TO-92 variant with 2.495 V VREF, ±1% tolerance, and 0.4 Ω dynamic impedance; rated for -40°C to 105°C operation. | Suitable for extended-temperature industrial or automotive environments where LM431ACZ/NOPB's 0°C–70°C range is insufficient. | Choose AS431ATZ for designs requiring wider ambient operating range or improved impedance spec without PCB change. |
Compared with TL431ACZ and AS431ATZ, LM431ACZ/NOPB offers cost-optimized commercial-grade performance with verified 0°C–70°C operation and sufficient accuracy for non-critical voltage monitoring and basic shunt regulation - making it ideal for cost-sensitive consumer and industrial control applications.
Availability
LM431ACZ/NOPB is available at Aetrix Electronics and suitable for adjustable linear power supplies, voltage monitoring systems, and current sink/source circuits requiring stable component supply with consistent TO-92 packaging and commercial-temperature reliability.
Supply support for LM431ACZ/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 delivering analog, embedded processing, and connectivity solutions with emphasis on reliability, precision, and broad application support.
The LM431 product line was designed for cost-effective, temperature-stable voltage reference and shunt regulation in commercial power management, monitoring, and protection circuits - targeting simplicity, wide output adjustability, and robustness in TO-92, SOT-23, and SOIC packages.
FAQ
What is the reference voltage tolerance of LM431ACZ/NOPB?
The LM431ACZ/NOPB has a reference voltage (VREF) of 2.47 V to 2.52 V at 25°C, corresponding to ±2% initial tolerance. This is confirmed in Section 6.5 of the SNVS020H datasheet under "Electrical Characteristics" for the LM431A grade. The part maintains this specification across its 0°C to 70°C operating range with ≤±17 mV total deviation.
Can LM431ACZ/NOPB replace a standard Zener diode?
Yes, LM431ACZ/NOPB is explicitly designed as a precision replacement for Zener diodes in applications requiring better temperature stability, lower dynamic impedance, and adjustable output. Unlike fixed Zeners, it achieves 2.5 V–36 V programmability with external resistors and exhibits 50 ppm/°C tempco versus typical Zener drift of >100 ppm/°C.
What is the maximum power dissipation for LM431ACZ/NOPB in TO-92 package?
LM431ACZ/NOPB in TO-92 (LP) package has a maximum internal power dissipation of 0.78 W at 25°C ambient, per Absolute Maximum Ratings (Section 6.1). Above 25°C, it derates linearly at 6.2 mW/°C - limiting usable power at 70°C ambient to approximately 0.49 W.
Does LM431ACZ/NOPB require an external capacitor for stability?
No, LM431ACZ/NOPB does not require an external capacitor for basic shunt regulation. However, TI recommends a 0.1 µF ceramic bypass capacitor on the input if noise reduction is needed. Stability boundaries depend on output capacitance and feedback network layout - see Figure 2 in the datasheet for oscillation risk zones.
What are the key differences between LM431ACZ/NOPB and LM431CIZ/NOPB?
LM431ACZ/NOPB is rated for 0°C to 70°C operation with ±2% VREF tolerance, while LM431CIZ/NOPB offers tighter ±0.5% VREF tolerance and extended –40°C to 85°C operation. Both use identical TO-92 packaging and pinout, but LM431CIZ/NOPB targets higher-precision, wider-temperature industrial applications at higher cost.
LM431ACZ/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Package/Case:
- TO-226-3, TO-92-3 (TO-226AA)
- Series:
- -
- Packaging:
- Box
- 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:
- Through Hole
- Supplier Device Package:
- TO-92-3
LM431ACZ/NOPB FAQ
1.How can I place an order for LM431ACZ/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM431ACZ/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 LM431ACZ/NOPB reliable?
The price and inventory of LM431ACZ/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM431ACZ/NOPB is usually 5 days.
3.What payment methods are accepted for LM431ACZ/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM431ACZ/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM431ACZ/NOPB?
LM431ACZ/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM431ACZ/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 LM431ACZ/NOPB?
For technical support, including LM431ACZ/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM431ACZ/NOPB requirements.
6.How does Aetrix verify that LM431ACZ/NOPB is sourced from the original manufacturer or authorized distributors?
All LM431ACZ/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 LM431ACZ/NOPB meets industry standards.
7.What is the process for return or replacement of LM431ACZ/NOPB?
All LM431ACZ/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM431ACZ/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 LM431ACZ/NOPB part is unused and in its original packaging.
Return procedure for LM431ACZ/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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