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Texas Instruments LM431BIM3X
- Part No.:
- LM431BIM3X
- Manufacturer:
- Texas Instruments
- Category:
- Voltage Reference
- Package:
- TO-236-3, SC-59, SOT-23-3
- Datasheet:
-
LM431BIM3X.pdf
- Description:
- IC VREF SHUNT ADJ 1% SOT23-3
- Quantity:
- Payment:
- Shipping:
Inventory:4,877
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Product details
Overview
LM431BIM3X from Texas Instruments is an adjustable precision shunt regulator IC with 2.5 V reference voltage, ±10 mV initial tolerance (B-grade), 50 ppm/°C average temperature coefficient, and operation up to 36 V cathode voltage - used as a programmable Zener replacement in feedback loops of linear and switching power supplies.
For engineers reviewing the LM431BIM3X datasheet, LM431BIM3X pinout, LM431BIM3X application, or LM431BIM3X equivalent, this page delivers verified electrical specs, SOT-23-3 package mapping, thermal derating guidance, and real-world use cases including overvoltage protection and current source design.
Technical Context
The LM431BIM3X functions as a 3-terminal adjustable shunt regulator: its reference pin senses a divided output voltage, and it sinks cathode current to maintain regulation. It operates in closed-loop mode with external resistor dividers or open-loop comparator mode with independent reference input.
It features low dynamic output impedance (0.5 Ω typical), fast turn-on response, and low-output noise - enabled by internal bandgap reference and transconductance amplifier architecture. Thermal hysteresis is characterized at ±0.5 mV after cycling between 0°C and 70°C.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reference Voltage (VREF) | 2.50 V ±10 mV (B-grade, 25°C) - sets minimum programmable output at 2.5 V; actual output = VREF × (1 + R1/R2) |
| Temperature Coefficient | 50 ppm/°C average - ensures ≤1.75 mV drift over –40°C to +85°C industrial range |
| Cathode Voltage Range | 2.5 V to 36 V - supports wide output programming without external series pass transistor |
| Min/Max Cathode Current | 0.4 mA / 100 mA - defines stable regulation envelope; below 0.4 mA, device exits regulation |
| Dynamic Output Impedance | 0.5 Ω typical - provides tight load regulation and high PSRR in shunt configurations |
| Reference Input Current | 2–4 μA - enables high-impedance feedback networks; contributes <1 mV error at R1 = 100 kΩ |
| ESD Rating (HBM) | ±2500 V - meets standard handling requirements without special ESD precautions beyond conductive foam |
Pinout & Package
SOT-23-3 package (DBZ drawing), 2.92 mm × 1.30 mm body size, single-row 3-pin surface-mount format with gull-wing leads. Pin 1 = Cathode, Pin 2 = Reference, Pin 3 = Anode.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode (Pin 1) | Output voltage node / shunt current sink | Connected to regulated output rail; sinks all excess current to maintain VOUT stability |
| Reference (Pin 2) | Feedback sense input | High-impedance node tied to resistor divider midpoint; triggers regulation when voltage reaches VREF |
| Anode (Pin 3) | Ground reference / current return path | Typically connected to system ground; completes shunt current path through external series resistor |
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 |
| Industrial temperature range | –40°C to +85°C operation - qualified for embedded power control in harsh environments |
| Low quiescent current | Reference input current ≤4 μA - enables battery-powered monitoring circuits with minimal standby drain |
| Stable regulation at low IZ | Regulates down to 0.4 mA cathode current - supports ultra-low-power biasing in sensing applications |
| Fast turn-on response | Sub-microsecond activation - suitable for transient-sensitive overvoltage crowbar circuits |
Applications
| Switch-Mode Power Supply Feedback | Overvoltage Protection Circuit |
|---|---|
|
Use Scenario: Secondary-side voltage sensing in isolated flyback converters with optocoupler feedback. IC Role / Device Role / Timing Role: Adjustable shunt regulator providing precise 2.5 V reference to optocoupler LED driver. Use Value: Enables ±1% output regulation across line/load/temperature; replaces discrete Zener + transistor with single 3-pin IC. |
Use Scenario: Monitoring 12 V automotive rail for >13.8 V fault condition to trigger shutdown. IC Role / Device Role / Timing Role: Precision voltage comparator with hysteresis via external resistor network. Use Value: Accurate trip point (±10 mV tolerance) prevents nuisance tripping; low tempco avoids drift in under-hood environments. |
| Constant Current Sink | Three-Terminal Regulator Enhancement |
|
Use Scenario: LED biasing in industrial status indicators requiring stable 20 mA drive. IC Role / Device Role / Timing Role: Shunt-based current regulator with cathode tied to constant-voltage source. Use Value: Delivers 20 mA ±1% over 0–70°C using only LM431BIM3X + single 120 Ω resistor - no op-amp needed. |
Use Scenario: Improving output accuracy of LM7805 fixed LDO by replacing internal bandgap with external LM431BIM3X reference. IC Role / Device Role / Timing Role: External precision reference injected into ADJ pin of three-terminal regulator. Use Value: Reduces output error from ±2% to ±0.5%; maintains thermal stability without adding complexity. |
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 pinout (SOT-23-3), C-grade (±2% VREF), 100 ppm/°C tempco, higher IREF (3–12 μA) | Lower precision; less suitable for <±1% systems but adequate for cost-sensitive consumer supplies | Select TL431CDBVR where ±2% output tolerance is acceptable and RoHS compliance is required. |
| AS431ASTU | Pin-compatible SOT-23-3, B-grade (±1%), 50 ppm/°C, 1.5 μA max IREF, -40°C to +105°C rating | Extended temperature range and lower input current improve performance in automotive under-hood designs | Choose AS431ASTU for AEC-Q100-compliant designs requiring operation beyond +85°C ambient. |
Compared with TL431CDBVR and AS431ASTU, the LM431BIM3X offers tighter initial VREF tolerance (±0.4%) and proven industrial reliability at lower cost than automotive-qualified variants - making it optimal for high-accuracy industrial power management where extended temperature is not required.
Availability
LM431BIM3X is available at Aetrix Electronics and suitable for adjustable power supply feedback, overvoltage protection, and precision current sink applications requiring stable component supply across production lifecycles.
Supply support for LM431BIM3X 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 designing analog ICs, embedded processors, and digital signal solutions for industrial, automotive, and communications markets.
The LM431 product line delivers precision shunt regulation for feedback, monitoring, and reference applications - engineered for stability, low drift, and compatibility with legacy Zener-based designs.
FAQ
What is the maximum cathode voltage rating for LM431BIM3X?
The LM431BIM3X has an absolute maximum cathode voltage rating of 37 V. Continuous operation is specified up to 36 V. Exceeding 37 V risks permanent damage. This limit applies regardless of current level and must be respected in crowbar or overvoltage clamp designs where transient spikes may occur. The LM431BIM3X datasheet explicitly states this in Section 6.1 Absolute Maximum Ratings.
Does LM431BIM3X require an external capacitor for stability?
No, the LM431BIM3X does not require an external capacitor for basic regulation stability. However, TI recommends a 0.1-µF ceramic bypass capacitor on the input if noise susceptibility is a concern. Stability boundaries depend on external resistor values and load capacitance - Figure 2 in the LM431BIM3X datasheet defines safe operating regions to avoid oscillation.
What is the thermal derating for LM431BIM3X in SOT-23 package?
The LM431BIM3X in SOT-23 (DBZ) package has a junction-to-ambient thermal resistance (RθJA) of 267.7°C/W. At ambient temperatures above 25°C, power dissipation must be derated at 2.2 mW/°C. For example, at 70°C ambient, maximum allowable power drops to 0.28 W − (45 × 0.0022 W) = 0.181 W - corresponding to ~75 mA at 2.5 V drop.
Can LM431BIM3X replace a standard 5.1 V Zener diode directly?
Yes, the LM431BIM3X can directly replace a 5.1 V Zener diode when configured with R1 = 1.05 kΩ and R2 = 1 kΩ (yielding VOUT = 2.5 × (1 + 1.05) = 5.125 V). Unlike passive Zeners, it requires no minimum current to maintain regulation - only 0.4 mA cathode current - and exhibits far better temperature stability (50 ppm/°C vs. typical Zener's 100–500 ppm/°C).
What does the 'B' in LM431BIM3X indicate?
The 'B' in LM431BIM3X denotes the reference voltage tolerance grade: ±10 mV (±0.4%) at 25°C, tighter than 'C' grade (±20 mV) and looser than 'A' grade (±5 mV). This grading is confirmed in Section 6.5 Electrical Characteristics of the LM431BIM3X datasheet, where VREF min/max values for LM431B are listed as 2.485 V / 2.51 V.
LM431BIM3X 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):
- 2.495V
- 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:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-23-3
LM431BIM3X FAQ
1.How can I place an order for LM431BIM3X through Aetrix?
Please submit a Request for Quotation (RFQ) for LM431BIM3X 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 LM431BIM3X reliable?
The price and inventory of LM431BIM3X are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM431BIM3X is usually 5 days.
3.What payment methods are accepted for LM431BIM3X?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM431BIM3X transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM431BIM3X?
LM431BIM3X orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM431BIM3X 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 LM431BIM3X?
For technical support, including LM431BIM3X datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM431BIM3X requirements.
6.How does Aetrix verify that LM431BIM3X is sourced from the original manufacturer or authorized distributors?
All LM431BIM3X 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 LM431BIM3X meets industry standards.
7.What is the process for return or replacement of LM431BIM3X?
All LM431BIM3X units undergo pre-shipment inspection (PSI). If there is an issue with LM431BIM3X, 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 LM431BIM3X part is unused and in its original packaging.
Return procedure for LM431BIM3X:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM431BIM3X Tags
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AZ431LANTR-G1
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