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Texas Instruments LM431CIM3X
- Part No.:
- LM431CIM3X
- Manufacturer:
- Texas Instruments
- Category:
- Voltage Reference
- Package:
- TO-236-3, SC-59, SOT-23-3
- Datasheet:
-
LM431CIM3X.pdf
- Description:
- IC VREF SHUNT -0.6/+0.4% SOT23-3
- Quantity:
- Payment:
- Shipping:
Inventory:2,120
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Product details
Overview
LM431CIM3X from Texas Instruments is a precision adjustable shunt voltage regulator in SOT-23-3 package, featuring 2.5 V reference voltage (±10 mV tolerance), 50 ppm/°C average temperature coefficient, 0.5 Ω dynamic output impedance, and operation from 2.5 V to 36 V output range - used for voltage monitoring and current sink circuits in industrial power supplies.
For engineers reviewing the LM431CIM3X datasheet, LM431CIM3X pinout, LM431CIM3X application, or LM431CIM3X equivalent, this page delivers verified electrical specs, thermal derating guidance, SOT-23 terminal mapping, and validated alternative parts for precision shunt regulation design-in.
Technical Context
The LM431CIM3X implements a bandgap-referenced error amplifier driving an NPN pass transistor, enabling precise shunt regulation via external resistor divider feedback to the REF pin. Its internal architecture ensures stable closed-loop operation with cathode current between 1 mA and 100 mA.
It operates in two functional modes: closed-loop shunt regulation (REF tied to output via resistive divider) and open-loop comparator mode (REF driven externally). Thermal hysteresis is specified at ±0.5 mV after cycling between 0°C and 70°C, reflecting package-induced stress effects on reference accuracy.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reference Voltage (VREF) | 2.50 V ±10 mV at 10 mA - sets minimum programmable output; actual output = VREF × (1 + R1/R2) |
| Temperature Coefficient | 50 ppm/°C average - ensures ≤3.5 mV drift over –40°C to +85°C operating range |
| Dynamic Output Impedance | 0.5 Ω typical - enables low-noise, high-stability regulation under load transients |
| Cathode Voltage Range | 2.5 V to 36 V - supports wide-range programmable outputs without external components |
| Minimum Cathode Current | 1 mA - defines lowest usable shunt current before regulation loss; critical for low-power designs |
| OFF-State Current | 1 μA max at 36 V - ensures minimal leakage when disabled or in undervoltage lockout |
| ESD Rating (HBM) | ±2500 V - requires standard ESD handling but no special protection circuitry |
Pinout & Package
SOT-23-3 package (DBZ drawing), 2.92 mm × 1.30 mm body, surface-mount, RoHS-compliant with CU SN finish, MSL Level-1.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode (Pin 1) | Output / Shunt current path | Main current sink node; connects to supply rail and load; voltage at this pin equals regulated output |
| Reference (Pin 2) | Feedback input | High-impedance input (≤4 μA) sensing voltage divider midpoint; sets regulation point when VREF = 2.5 V |
| Anode (Pin 3) | Ground reference | Return path for internal amplifier and shunt current; must be connected to system ground or common reference |
Key Features
| Feature | Design Value |
|---|---|
| Adjustable output voltage | Programmable from 2.5 V to 36 V using only two external resistors - eliminates need for multiple fixed Zener diodes |
| Low-output noise | Typical 15 μVRMS (10 Hz–10 kHz) - suitable for precision analog references and ADC biasing |
| Fast turn-on response | 1.5 μs typical rise time - supports dynamic load regulation and fast fault detection in protection circuits |
| Temperature-compensated reference | Stable over full –40°C to +85°C range with <±17 mV total deviation - enables reliable operation in industrial environments |
| Low quiescent current | Reference input current ≤4 μA - minimizes power loss in battery-powered or energy-harvesting systems |
Applications
| Adjustable Linear Power Supply | Voltage Monitoring Circuit |
|---|---|
Use Scenario: Regulating unregulated DC input (e.g., rectified AC or DC-DC pre-regulator) to stable 5 V, 12 V, or custom voltage for microcontroller peripherals. IC Role / Device Role / Timing Role: Shunt regulator controlling output by sinking excess current through cathode; REF pin senses output via resistive divider. Use Value: Replaces discrete Zener + transistor solutions with single-component, temperature-stable regulation and <0.5 Ω output impedance. |
Use Scenario: Detecting overvoltage condition on a 24 V industrial bus to trigger shutdown or alarm. IC Role / Device Role / Timing Role: Precision threshold comparator - REF pin biased to 2.45 V; cathode pulled high via pull-up; output swings when bus exceeds setpoint. Use Value: Achieves ±1% trip accuracy over temperature without trimming, leveraging 50 ppm/°C reference stability. |
| Constant Current Sink | Zener Diode Replacement |
Use Scenario: Driving LED strings or calibration loads requiring stable 20 mA current independent of supply variation. IC Role / Device Role / Timing Role: Current sink configured with REF grounded and cathode connected to load; anode to return; current set by Rsense = 2.5 V / Iset. Use Value: Delivers 0.5% current accuracy over temperature vs. ±5% for standard Zeners, with no forward-voltage dependency. |
Use Scenario: Upgrading legacy 3.3 V or 5.1 V Zener-based voltage clamp in power supply feedback or protection networks. IC Role / Device Role / Timing Role: Adjustable shunt element replacing fixed Zener; same 3-pin TO-92 footprint possible with LM431CIZ, but LM431CIM3X offers SOT-23 space savings. Use Value: Enables exact voltage setting (e.g., 3.30 V) without stockkeeping multiple Zener tolerances; reduces BOM count and improves yield. |
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. LM431CIM3X's 0.4%); higher 200 ppm/°C tempco; SOT-23-3 pinout identical | Lower precision; acceptable where cost > accuracy; not suitable for <±0.5% output stability requirements | Select TL431CDBVR only if budget constraints outweigh reference stability needs and thermal drift is mitigated externally |
| AS431ARTDT | Pin-compatible SOT-23-3; 2.5 V ref with 0.5% tolerance; 100 ppm/°C tempco; 1.5 Ω dynamic impedance (vs. 0.5 Ω) | Higher output impedance limits transient response; wider tempco increases drift in wide-temperature deployments | AS431ARTDT fits layout but degrades regulation fidelity - use only when LM431CIM3X is unavailable and system allows ±10 mV additional error |
Compared with TL431CDBVR and AS431ARTDT, the LM431CIM3X delivers superior thermal stability (50 ppm/°C vs. ≥100 ppm/°C) and lower dynamic impedance (0.5 Ω vs. ≥1.5 Ω), making it preferred for precision industrial monitoring and low-noise analog supply rails.
Availability
LM431CIM3X is available at Aetrix Electronics and suitable for adjustable linear power supplies, voltage monitoring circuits, constant current sink designs, and Zener diode replacement applications requiring stable component supply across industrial temperature ranges.
Supply support for LM431CIM3X 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 personal electronics markets since 1930.
The LM431 product line was designed specifically for precision shunt regulation in space-constrained, thermally demanding applications - offering grade-specific tolerances (A/B/C), multiple packages (SOT-23, SOIC, TO-92), and guaranteed stability from –40°C to +85°C.
FAQ
What is the maximum cathode voltage rating for LM431CIM3X?
The absolute maximum cathode voltage for LM431CIM3X is 37 V. Operation above this level risks permanent damage. For reliable long-term use, TI specifies a recommended maximum cathode voltage of 36 V under normal operating conditions, aligned with its 2.5 V to 36 V programmable output range.
Does LM431CIM3X require an external capacitor for stability?
No, LM431CIM3X does not require an external capacitor for basic shunt regulation. However, TI recommends a 0.1-μF ceramic bypass capacitor near the cathode pin to reduce input noise that could modulate the output. Stability boundaries depend on external resistor values and load capacitance, as shown in Figure 2 of the datasheet.
What is the thermal derating for LM431CIM3X in SOT-23 package?
LM431CIM3X in SOT-23 package has a rated internal power dissipation of 0.28 W at 25°C ambient. Above 25°C, it must be derated at 2.2 mW/°C. At 85°C ambient, maximum allowable power dissipation drops to 0.15 W - requiring careful calculation of cathode current and voltage to avoid thermal shutdown or parametric shift.
Can LM431CIM3X be used as a comparator?
Yes, LM431CIM3X can operate in open-loop comparator mode: drive the REF pin with an external voltage source while leaving the cathode open or weakly pulled up. When the REF voltage exceeds 2.5 V, the cathode sinks current; below 2.5 V, it remains high-impedance. This enables overvoltage/undervoltage detection without additional ICs.
What does the 'C' in LM431CIM3X indicate?
The 'C' in LM431CIM3X denotes the commercial-grade reference voltage tolerance: 2.50 V ±10 mV (0.4%) at 25°C. This distinguishes it from 'A' (±0.5%) and 'B' (±0.2%) grades. The 'I' indicates –40°C to +85°C operating temperature range, 'M3X' confirms SOT-23-3 package in 3000-unit tape-and-reel format.
LM431CIM3X 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:
- Obsolete
- Reference Type:
- Shunt
- Output Type:
- Adjustable
- Voltage - Output (Min/Fixed):
- 2.5V
- Voltage - Output (Max):
- 37 V
- Current - Output:
- 100 mA
- Tolerance:
- -0.6%, +0.4%
- Temperature Coefficient:
- 50ppm/°C Typical
- Noise - 0.1Hz to 10Hz:
- -
- Noise - 10Hz to 10kHz:
- -
- Voltage - Input:
- -
- Current - Supply:
- -
- Current - Cathode:
- 1 mA
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-23-3
LM431CIM3X FAQ
1.How can I place an order for LM431CIM3X through Aetrix?
Please submit a Request for Quotation (RFQ) for LM431CIM3X 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 LM431CIM3X reliable?
The price and inventory of LM431CIM3X are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM431CIM3X is usually 5 days.
3.What payment methods are accepted for LM431CIM3X?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM431CIM3X transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM431CIM3X?
LM431CIM3X orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM431CIM3X 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 LM431CIM3X?
For technical support, including LM431CIM3X datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM431CIM3X requirements.
6.How does Aetrix verify that LM431CIM3X is sourced from the original manufacturer or authorized distributors?
All LM431CIM3X 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 LM431CIM3X meets industry standards.
7.What is the process for return or replacement of LM431CIM3X?
All LM431CIM3X units undergo pre-shipment inspection (PSI). If there is an issue with LM431CIM3X, 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 LM431CIM3X part is unused and in its original packaging.
Return procedure for LM431CIM3X:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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