My Inquiry
My Account
Texas Instruments LM431CIM
- Part No.:
- LM431CIM
- Manufacturer:
- Texas Instruments
- Category:
- Voltage Reference
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LM431CIM.pdf
- Description:
- IC VREF SHUNT -0.6%/+0.4% 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,000
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
LM431CIM from Texas Instruments is an adjustable precision shunt regulator IC with 2.5 V reference voltage, ±17 mV reference voltage deviation over temperature, 0.5 Ω dynamic output impedance, and operation across –40°C to +85°C. It functions as a programmable Zener replacement in feedback loops of linear and switching power supplies, voltage monitors, and current sink circuits.
For engineers reviewing the LM431CIM datasheet, LM431CIM pinout, LM431CIM application, or LM431CIM equivalent, this page delivers verified package mapping (SOIC-8), confirmed terminal roles (Cathode, Reference, Anode), thermal derating guidance (6.5 mW/°C above 25°C), and two validated alternative parts for industrial-grade shunt regulation designs.
Technical Context
The LM431CIM implements a bandgap-referenced error amplifier driving an NPN output stage in a 3-terminal shunt topology. Its internal reference is trimmed to 2.50 V (±1% initial tolerance) and compensated for stability across –40°C to +85°C, achieving 50 ppm/°C average temperature coefficient. Regulation occurs when cathode current (IZ) remains between 0.4 mA and 100 mA.
It operates in closed-loop mode using external resistor dividers to set output voltage from 2.5 V to 36 V, or in open-loop comparator mode. The SOIC-8 package provides separate Anode pins (pins 2, 3, 6, 7) for low-inductance grounding and supports stable operation with minimal external components - only two resistors and optionally a bypass capacitor.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reference Voltage (VREF) | 2.50 V (typical), ±17 mV deviation over full –40°C to +85°C range - enables precise voltage setting without calibration |
| Dynamic Output Impedance | 0.5 Ω (typical at DC) - ensures tight regulation under load transients and minimizes output voltage droop |
| Cathode Current Range | 0.4 mA to 100 mA - defines minimum bias and maximum shunt capability for stable regulation |
| Temperature Coefficient | 50 ppm/°C (average) - guarantees predictable drift in precision references and monitoring circuits |
| Output Voltage Range | 2.5 V to 36 V (programmable via R1/R2 divider) - replaces fixed Zeners while supporting wide supply and rail requirements |
| ESD Rating (HBM) | ±2500 V - meets industrial handling requirements without additional protection circuitry |
| Thermal Resistance (RθJA) | 126.9 °C/W (SOIC-8) - requires derating by 6.5 mW/°C above 25°C ambient for safe continuous operation |
Pinout & Package
LM431CIM is housed in an 8-pin SOIC (D package) with 4.90 mm × 3.91 mm body size and RoHS-compliant CuSn lead finish. Pin 4 and Pin 5 are internally unconnected (NC). Anode pins (2, 3, 6, 7) must be tied together and grounded for optimal noise immunity and thermal performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode (Pin 1) | Shunt current output / regulated voltage node | Connects to supply rail or feedback point; carries full shunt current; voltage at this pin equals programmed output |
| Reference (Pin 8) | Feedback input / precision reference sense | Connects to resistor divider midpoint; senses output voltage; draws only 2–4 μA, enabling high-impedance feedback networks |
| Anode (Pins 2, 3, 6, 7) | Ground return path for internal amplifier and output stage | Must be shorted externally and connected to low-impedance ground; multiple pins reduce bond wire inductance and improve stability |
| NC (Pins 4, 5) | No internal connection | Leave floating; no routing or soldering required; improves layout flexibility and reduces parasitic coupling |
Key Features
| Feature | Design Value |
|---|---|
| Adjustable output voltage | Set from 2.5 V to 36 V using only two external resistors - eliminates need for multiple Zener values and simplifies BOM |
| Low-output noise | Typical 0.5 Ω dynamic impedance and <1 μV/√Hz noise floor - preserves signal integrity in sensitive analog monitoring paths |
| Fast turn-on response | Sub-microsecond recovery from OFF-state (IZ < 0.4 mA) - supports dynamic load detection and fast fault response in protection circuits |
| Temperature-compensated reference | Stable 2.50 V reference across –40°C to +85°C with 50 ppm/°C avg TC - enables reliable operation in automotive and industrial environments |
| Space-saving SOIC-8 package | 4.90 mm × 3.91 mm footprint with 4-anode configuration - improves thermal dissipation and reduces PCB area vs TO-92 or SOT-23 variants |
Applications
| Switch-Mode Power Supply Feedback | Voltage Monitoring & Threshold Detection |
|---|---|
|
Use Scenario: Secondary-side feedback in isolated flyback or forward converters where optocoupler-coupled regulation is required. IC Role / Device Role / Timing Role: Shunt regulator providing precise 2.5 V reference to drive optocoupler LED; sets output voltage via R1/R2 divider on cathode side. Use Value: Enables ±1% output accuracy over line, load, and temperature; replaces discrete Zener + transistor with single IC and two resistors. |
Use Scenario: Overvoltage lockout (OVLO) and undervoltage detection in battery management or DC bus monitoring systems. IC Role / Device Role / Timing Role: Precision comparator with built-in reference; Reference pin biased to threshold voltage; Cathode pulled high until trip point reached. Use Value: Delivers 50 ppm/°C threshold stability without external reference IC; supports clean hysteresis via resistor network on Reference pin. |
| Programmable Current Sink | Zener Diode Replacement in Linear Regulators |
|
Use Scenario: Constant-current source for LED biasing, sensor excitation, or analog front-end calibration. IC Role / Device Role / Timing Role: Shunt regulator configured with fixed cathode voltage and variable load on Anode; sinks current proportional to R1 value. Use Value: Achieves <1% current accuracy over temperature; eliminates need for matched transistor pairs or op-amp-based current sources. |
Use Scenario: Output voltage adjustment in three-terminal LDOs (e.g., LM317) or series pass regulator feedback networks. IC Role / Device Role / Timing Role: Replaces fixed Zener diode in ADJ pin feedback loop; sets reference voltage more precisely than standard Zeners. Use Value: Improves output voltage tolerance from ±5% (Zener) to ±1% (LM431CIM); reduces temperature-induced drift by >5× vs 5% tolerance Zeners. |
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 SOIC-8 package, but rated for 0°C to 70°C (commercial grade); 2.495 V reference (±0.5% initial), lower tempco (39 ppm/°C) | Not qualified for extended temperature (-40°C to +85°C); unsuitable for automotive or industrial ambient environments | Select TL431CDBVR only for cost-sensitive commercial applications where extended temperature range is not required. |
| LM431BIM/NOPB | Same SOIC-8 package and -40°C to +85°C rating; tighter 2.495 V reference (±0.5% initial), 8 mV max VDEV over temperature | Higher precision reference with improved thermal stability; higher unit cost and lower availability than LM431CIM | Choose LM431BIM/NOPB when reference accuracy better than ±1% and sub-10 mV VDEV are mandatory for system-level calibration. |
Compared with TL431CDBVR, LM431CIM provides guaranteed operation down to –40°C and looser initial tolerance - making it more robust for harsh environments but less precise. Against LM431BIM/NOPB, LM431CIM trades 0.5% reference accuracy for broader availability and lower cost in industrial-grade designs where ±1% is sufficient.
Availability
LM431CIM is available at Aetrix Electronics and suitable for industrial power supplies, battery voltage monitors, and programmable current sink circuits requiring stable component supply across extended temperature ranges.
Supply support for LM431CIM 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 specializing in analog and embedded processing technologies, with leadership in precision analog ICs and power management solutions.
The LM431 product line delivers adjustable shunt regulation for feedback, monitoring, and protection functions in power conversion and sensing systems - designed specifically for reliability in industrial, telecom, and automotive applications.
FAQ
What is the operating temperature range of the LM431CIM?
The LM431CIM is rated for operation from –40°C to +85°C, qualifying it for industrial-grade applications. This range is explicitly defined in the Absolute Maximum Ratings and Recommended Operating Conditions sections of the SNVS020H datasheet. The device maintains specified electrical characteristics - including reference voltage deviation and dynamic impedance - across this full span, unlike commercial-grade variants such as TL431CDBVR.
How does the LM431CIM differ from the LM431ACM and LM431BCM variants?
The LM431CIM differs from LM431ACM and LM431BCM in its reference voltage tolerance and temperature stability: LM431CIM has ±1% initial tolerance (2.485–2.51 V) and ±17 mV VDEV over temperature, while LM431ACM offers ±2% (2.44–2.55 V) and LM431BCM provides ±0.5% (2.485–2.515 V). All share the same SOIC-8 package and –40°C to +85°C rating, but LM431CIM balances cost and performance for general industrial use.
Can the LM431CIM be used as a comparator?
Yes, the LM431CIM can operate in open-loop comparator mode per Section 8.4 of the datasheet. When the Reference pin is driven by an external voltage source instead of a resistor divider, the Cathode switches between high-impedance and low-impedance states based on whether the input exceeds 2.5 V. This enables threshold detection, overvoltage protection, and delay timing - though propagation delay is not characterized in the datasheet.
What is the minimum cathode current required for regulation in the LM431CIM?
The LM431CIM requires a minimum cathode current (IZ(MIN)) of 0.4 mA to maintain regulation, as specified in Section 6.5 of the SNVS020H datasheet. Below this threshold, the device exits regulation and behaves as an open circuit. Designers must ensure the series resistor (RS) and load conditions sustain ≥0.4 mA across all operating conditions - especially at minimum input voltage and maximum load current.
Is the LM431CIM pin-compatible with other LM431 package variants like SOT-23 or TO-92?
No, the LM431CIM in SOIC-8 is not pin-compatible with SOT-23 or TO-92 variants. SOIC-8 uses 8 pins with four dedicated Anode connections (pins 2,3,6,7) and NC pins (4,5), whereas SOT-23 and TO-92 are 3-pin packages with single Anode, Cathode, and Reference terminals. PCB layout, thermal design, and grounding strategy must be re-validated when changing packages - no drop-in replacement is possible.
LM431CIM 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):
- 2.5V
- 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:
- 8-SOIC
LM431CIM FAQ
1.How can I place an order for LM431CIM through Aetrix?
Please submit a Request for Quotation (RFQ) for LM431CIM 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 LM431CIM reliable?
The price and inventory of LM431CIM are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM431CIM is usually 5 days.
3.What payment methods are accepted for LM431CIM?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM431CIM transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM431CIM?
LM431CIM orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM431CIM 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 LM431CIM?
For technical support, including LM431CIM datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM431CIM requirements.
6.How does Aetrix verify that LM431CIM is sourced from the original manufacturer or authorized distributors?
All LM431CIM 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 LM431CIM meets industry standards.
7.What is the process for return or replacement of LM431CIM?
All LM431CIM units undergo pre-shipment inspection (PSI). If there is an issue with LM431CIM, 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 LM431CIM part is unused and in its original packaging.
Return procedure for LM431CIM:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM431CIM Tags
-
TL431AIDBZR
Texas Instruments
-
TL431BQDBZR
Texas Instruments
-
AN431AN-ATRG1
Diodes Incorporated
-
LM4040CYM3-2.5-TR
Microchip Technology
-
LM4040CYM3-4.1-TR
Microchip Technology
-
LM4040EIM3-2.5/NOPB
Texas Instruments
-
AZ431LBNTR-G1
Diodes Incorporated
-
LM4040D20IDBZR
Texas Instruments
-
LM4041DIM3-ADJ/NOPB
Texas Instruments
-
LM4040DIM3X-2.5/NOPB
Texas Instruments
-
LM4040DIM3-2.5/NOPB
Texas Instruments
-
AZ431LANTR-G1
Diodes Incorporated
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
