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Texas Instruments LM431ACM
- Part No.:
- LM431ACM
- Manufacturer:
- Texas Instruments
- Category:
- Voltage Reference
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LM431ACM.pdf
- Description:
- IC VREF SHUNT ADJ 2.2% 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,956
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Product details
Overview
LM431ACM from Texas Instruments is a precision adjustable shunt voltage regulator in SOIC-8 package, featuring 2.495 V nominal reference voltage (VREF), ±17 mV max reference deviation over temperature, 0.75 Ω typical dynamic output impedance, and operation up to 36 V cathode voltage - widely used in feedback loops of isolated DC/DC converters and voltage monitoring circuits.
For engineers reviewing the LM431ACM datasheet, LM431ACM pinout, LM431ACM application, or LM431ACM equivalent, this page delivers verified electrical specs, SOIC-8 terminal mapping, thermal derating guidance, stability boundary data, and validated alternative options for precision shunt regulation design.
Technical Context
The LM431ACM operates as a 3-terminal programmable Zener with internal bandgap reference and error amplifier driving an NPN output stage. Its regulation relies on external resistor divider feedback to the REF pin, enabling precise output voltage setting from 2.5 V to 36 V via VOUT = VREF × (1 + R1/R2).
It functions in closed-loop shunt mode (IZ = 1–100 mA) or open-loop comparator mode, with thermal hysteresis <10 mV after cycling between 0°C and 70°C, and average temperature coefficient of 50 ppm/°C - ensuring stable reference performance across commercial temperature range (0°C to 70°C).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VREF (25°C) | 2.495 V nominal - sets minimum programmable output voltage; actual value varies ±0.025 V for LM431ACM grade |
| VREF Deviation (0°C to 70°C) | ±17 mV max - defines worst-case output voltage drift in temperature-critical applications |
| Dynamic Output Impedance | 0.75 Ω typical at DC - ensures low AC output impedance for stable feedback loop compensation |
| Cathode Voltage Range | 2.5 V to 36 V - supports wide-range output programming without external series pass transistor |
| Minimum Cathode Current | 1 mA - lowest current sustaining regulation; critical for low-power standby modes |
| Reference Input Current | 2–4 μA - enables high-impedance feedback networks with minimal loading error |
| ESD Rating (HBM) | ±2500 V - informs handling requirements during PCB assembly and test |
Pinout & Package
LM431ACM is housed in an 8-pin SOIC (D package) with 4.90 mm × 3.91 mm body size and RoHS-compliant CU SN lead finish. Pin 4 and Pin 5 are internally unconnected (NC); functional terminals occupy Pins 1 (Cathode), 2 (Reference), and 3/6/7 (Anode).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PIN 1 | Cathode | Output node where regulated voltage appears; sinks shunt current to maintain VOUT |
| PIN 2 | Reference | High-impedance input for feedback divider; regulates when voltage equals VREF |
| PINS 3, 6, 7 | Anode | Common ground return path; all three pins electrically tied to internal substrate |
| PINS 4, 5 | NC | No internal connection; must remain unconnected on PCB to avoid parasitic coupling |
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 Stability | Average TC of 50 ppm/°C and ±17 mV VREF drift over 0°C–70°C - enables stable references in non-ovenized environments |
| Fast Turn-On Response | Sub-microsecond turn-on time - supports dynamic load transient recovery in switching power supplies |
| Low-Output Noise | Typical 20 μVRMS (10 Hz–10 kHz) - suitable for precision analog sensing and DAC reference buffering |
| Low-Dynamic Output Impedance | 0.75 Ω at DC - minimizes output voltage perturbation under varying shunt current conditions |
Applications
| Isolated Flyback Converter Feedback | Voltage Monitoring Circuit |
|---|---|
Use Scenario: Secondary-side voltage sensing in optocoupler-based isolated DC/DC converters. IC Role / Device Role / Timing Role: Shunt regulator providing precise 2.5 V reference to drive optocoupler LED, closing primary-side regulation loop. Use Value: Enables ±1% output voltage accuracy across line/load/temperature while maintaining galvanic isolation. |
Use Scenario: Overvoltage detection in battery management systems or industrial power rails. IC Role / Device Role / Timing Role: Adjustable threshold comparator triggering protection circuitry when input exceeds setpoint. Use Value: Programmable trip point (e.g., 12.6 V for 3S Li-ion) with <10 mV hysteresis-induced error after thermal cycling. |
| Current Sink for LED Driver | Zener Diode Replacement |
Use Scenario: Constant-current sink for high-brightness LED strings in automotive lighting modules. IC Role / Device Role / Timing Role: Precision shunt regulating current through external sense resistor and LED path. Use Value: Delivers ±2% current accuracy over temperature with 0.75 Ω dynamic impedance minimizing current ripple. |
Use Scenario: Upgrading legacy 5.1 V Zener-based voltage clamp in microcontroller reset circuits. IC Role / Device Role / Timing Role: Adjustable shunt regulator replacing fixed Zener to improve tolerance and temperature drift. Use Value: Reduces reference drift from >100 ppm/°C (Zener) to 50 ppm/°C and improves initial tolerance from ±5% to ±1%. |
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 2.495 V VREF, but 0.22 Ω lower dynamic impedance (0.53 Ω typ); 100 mA max cathode current same | Higher gain and lower rZ improve phase margin in fast-switching flyback designs | Preferred for new designs requiring tighter loop stability; pin-compatible SOIC-8 replacement |
| LM431AIM/NOPB | Identical electrical specs but rated for –40°C to +85°C industrial temp range vs. LM431ACM's 0°C to +70°C | Suitable for extended-temperature industrial controls and outdoor power equipment | Select when ambient operating temperature exceeds 70°C; same SOIC-8 footprint and pinout |
Compared with LM431ACM, TL431ACDR offers superior dynamic output impedance for demanding control loops, while LM431AIM/NOPB extends operational reliability into industrial temperature ranges - both retain identical SOIC-8 packaging and reference programming behavior.
Availability
LM431ACM is available at Aetrix Electronics and suitable for isolated DC/DC converter feedback, voltage monitoring, and precision current sink applications requiring stable component supply across commercial temperature range.
Supply support for LM431ACM 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, embedded processing, and power management ICs, with decades of expertise in precision reference and power control solutions.
The LM431 product line was designed specifically for cost-sensitive, space-constrained applications needing adjustable shunt regulation - delivering Zener-level simplicity with bandgap-grade accuracy and thermal stability.
FAQ
What is the maximum cathode voltage rating for LM431ACM?
The absolute maximum cathode voltage for LM431ACM is 37 V, with recommended operating range up to 36 V. Exceeding 37 V risks permanent damage. This rating applies regardless of anode or reference pin biasing, and is specified in Section 6.1 of the SNVS020H datasheet. LM431ACM maintains regulation integrity within its 2.5 V–36 V programmable output window.
How does LM431ACM differ from LM431C-grade variants?
LM431ACM belongs to the 'A' grade with ±17 mV VREF deviation over 0°C–70°C, tighter than 'C' grade (±25 mV). Its VREF is 2.495 V (typ), versus LM431CCM's 2.500 V (typ). Both share SOIC-8 packaging and identical pinout, but LM431ACM offers improved initial accuracy and temperature stability - critical for applications demanding <1% output tolerance.
Can LM431ACM be used in open-loop comparator mode?
Yes, LM431ACM can operate in open-loop mode by applying an external voltage to the REF pin while holding cathode at fixed potential. In this configuration, it acts as a precision comparator with 2.5 V threshold and fast turn-on response. The device sinks current only when REF voltage exceeds VREF, enabling overvoltage latch or delay timer functions - detailed in Section 8.4 of the datasheet.
What is the thermal derating requirement for LM431ACM in SOIC-8 package?
LM431ACM in SOIC-8 has 0.81 W maximum internal power dissipation at 25°C ambient. Above 25°C, it must be derated at 6.5 mW/°C per Section 6.1. At 70°C ambient, usable power drops to 0.51 W. Junction temperature must not exceed 150°C. Thermal resistance RθJA is 126.9°C/W, confirming need for adequate copper area or airflow in high-dissipation designs.
Is LM431ACM RoHS compliant and lead-free?
Yes, LM431ACM/NOPB (orderable part) is RoHS compliant and lead-free, with Green (RoHS & no Sb/Br) eco plan and CU SN lead finish. It meets JEDEC MSL Level-1 moisture sensitivity and is qualified for standard reflow profiles. The "NOPB" suffix explicitly denotes lead-free, halogen-free compliance - confirmed in TI's Package Option Addendum dated 25-Jun-2016.
LM431ACM Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Series:
- -
- Packaging:
- Tube
- 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:
- ±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:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
LM431ACM FAQ
1.How can I place an order for LM431ACM through Aetrix?
Please submit a Request for Quotation (RFQ) for LM431ACM 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 LM431ACM reliable?
The price and inventory of LM431ACM are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM431ACM is usually 5 days.
3.What payment methods are accepted for LM431ACM?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM431ACM transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM431ACM?
LM431ACM orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM431ACM 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 LM431ACM?
For technical support, including LM431ACM datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM431ACM requirements.
6.How does Aetrix verify that LM431ACM is sourced from the original manufacturer or authorized distributors?
All LM431ACM 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 LM431ACM meets industry standards.
7.What is the process for return or replacement of LM431ACM?
All LM431ACM units undergo pre-shipment inspection (PSI). If there is an issue with LM431ACM, 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 LM431ACM part is unused and in its original packaging.
Return procedure for LM431ACM:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM431ACM Tags
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TL431AIDBZR
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TL431BQDBZR
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AN431AN-ATRG1
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LM4040CYM3-2.5-TR
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LM4040CYM3-4.1-TR
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LM4040EIM3-2.5/NOPB
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AZ431LBNTR-G1
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LM4040D20IDBZR
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LM4041DIM3-ADJ/NOPB
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LM4040DIM3X-2.5/NOPB
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LM4040DIM3-2.5/NOPB
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AZ431LANTR-G1
Diodes Incorporated
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