My Inquiry
My Account
Texas Instruments LM431BCMX
- Part No.:
- LM431BCMX
- Manufacturer:
- Texas Instruments
- Category:
- Voltage Reference
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LM431BCMX.pdf
- Description:
- IC VREF SHUNT ADJ 1% 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,017
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
LM431BCMX from Texas Instruments is a precision adjustable shunt voltage regulator with 2.5 V reference voltage, ±17 mV reference voltage deviation over temperature, 0.5 Ω dynamic output impedance, and operation up to 36 V cathode voltage - used in feedback loops of linear/switching power supplies and voltage monitoring circuits.
For engineers reviewing the LM431BCMX datasheet, LM431BCMX pinout, LM431BCMX application, or LM431BCMX equivalent, this page delivers verified package mapping (SOIC-8), confirmed thermal specs (RθJA = 126.9°C/W), validated operating current range (1–100 mA), and real-world design constraints for stable shunt regulation.
Technical Context
The LM431BCMX operates as a 3-terminal programmable shunt regulator where the reference pin senses a resistor-divider output voltage, and internal error amplifier drives the cathode to maintain VREF = 2.5 V at the reference node. Regulation requires minimum 1 mA cathode current and remains stable across 0°C to 70°C.
Its architecture replaces discrete Zener diodes by integrating temperature-compensated bandgap reference, high-gain error amplifier, and NPN pass transistor - enabling precise output voltage setting (2.5 V to 36 V) via two external resistors without requiring external bias components.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reference voltage (VREF) | 2.485–2.51 V at 25°C - sets base accuracy for programmable output voltage VO = VREF × (1 + R1/R2) |
| Reference voltage deviation | ±17 mV over full temperature range - defines worst-case output voltage drift in closed-loop designs |
| Dynamic output impedance | 0.5 Ω at DC - ensures low AC output impedance for ripple rejection in feedback paths |
| Cathode voltage range | 2.5 V to 36 V - supports wide-range output programming while maintaining regulation |
| Minimum cathode current | 0.4–1 mA - determines smallest allowable load current before regulation loss |
| Maximum cathode current | 150 mA absolute max, 100 mA recommended - defines upper current limit for safe continuous operation |
| Average tempco | 50 ppm/°C - quantifies typical reference voltage drift per degree Celsius change |
Pinout & Package
LM431BCMX is housed in an 8-pin SOIC (D package) with 4.90 mm × 3.91 mm body size, RoHS-compliant green finish, and moisture sensitivity level (MSL) 1 (260°C peak reflow).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (pins 2, 3, 6, 7) | Ground return path | Internally connected common node; must be tied to system ground for proper regulation |
| Cathode (pin 1) | Shunt output terminal | Connects to regulated output node; sinks current to ground to maintain set voltage |
| Reference (pin 8) | Feedback input | High-impedance input (2–4 μA) that senses resistor-divider voltage; sets regulation point |
| NC (pins 4, 5) | No connect | Not internally bonded; 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-stable reference | Guaranteed ±17 mV VREF deviation over 0°C to 70°C - enables reliable performance in commercial-temperature environments |
| Low dynamic output impedance | 0.5 Ω at DC - provides strong AC regulation for noise-sensitive feedback loops |
| Fast turn-on response | Enables rapid stabilization after power-up or transient events - critical for power supply sequencing |
| Low-output noise | Minimizes voltage perturbation in precision references - improves ADC/DAC reference stability |
Applications
| Switch-Mode Power Supply Feedback | Voltage Monitoring Circuit |
|---|---|
Use Scenario: Used in secondary-side feedback loop of isolated flyback converters to regulate output voltage via optocoupler-coupled signal. IC Role / Device Role / Timing Role: Adjustable shunt regulator providing precise 2.5 V reference for error amplifier comparison. Use Value: Enables accurate ±1% output regulation across line/load/temperature without custom trimming. |
Use Scenario: Monitors 12 V rail in industrial control systems to trigger fault flag when voltage drops below 11.4 V. IC Role / Device Role / Timing Role: Precision threshold detector with resistor-programmed trip point and hysteresis via external components. Use Value: Replaces dual op-amp comparator setup with single 3-pin device, reducing BOM count and board area. |
| Current Sink for LED Bias | Zener Diode Replacement |
Use Scenario: Provides constant 20 mA sink for indicator LEDs in automotive dashboard modules. IC Role / Device Role / Timing Role: Shunt-based current regulator where cathode connects to LED anode and anode to ground. Use Value: Delivers stable current independent of supply variation (9–16 V), eliminating need for ballast resistors. |
Use Scenario: Substitutes for 3.3 V Zener in microcontroller reset circuit requiring tighter tolerance and lower tempco. IC Role / Device Role / Timing Role: Precision shunt reference replacing passive Zener with integrated temperature compensation. Use Value: Reduces reference voltage drift from >100 ppm/°C (Zener) to 50 ppm/°C, improving reset threshold accuracy. |
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. LM431BCMX ±0.5%) and higher 2 μA max IREF | Lower cost; suitable where ±2% output tolerance is acceptable and lower quiescent current not required | Select TL431CDBVR for cost-sensitive consumer applications where tighter reference accuracy is unnecessary |
| AS431ASTU | Pin-compatible SOIC-8, ±1% VREF tolerance, 1.5 μA max IREF, but only rated to 30 V cathode voltage | Valid for ≤30 V outputs; unsuitable for 36 V designs or applications needing full LM431BCMX voltage range | Choose AS431ASTU only if output voltage stays ≤30 V and 1% tolerance meets system requirements |
Compared with TL431CDBVR and AS431ASTU, the LM431BCMX offers superior reference accuracy (±0.5%), wider cathode voltage range (36 V), and lower dynamic impedance (0.5 Ω), making it optimal for high-precision power supply feedback and industrial monitoring where stability and headroom matter.
Availability
LM431BCMX is available at Aetrix Electronics and suitable for switching power supplies, voltage monitoring systems, and current sink circuits requiring stable component supply across commercial temperature ranges (0°C to 70°C).
Supply support for LM431BCMX 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 was designed for high-accuracy voltage regulation in space-constrained power systems, delivering Zener-replacement functionality with integrated temperature compensation and programmable output capability.
FAQ
What is the reference voltage tolerance of the LM431BCMX?
The LM431BCMX has a reference voltage (VREF) tolerance of ±0.5% - specified as 2.485 V to 2.51 V at 25°C. This tight tolerance directly translates to higher accuracy in programmable output voltage configurations (VO = VREF × (1 + R1/R2)) compared to standard Zener diodes or looser-tolerance shunt regulators like the TL431.
Can the LM431BCMX replace a standard Zener diode in existing designs?
Yes, the LM431BCMX can directly replace many Zener diodes in shunt regulator applications - especially where improved temperature stability (50 ppm/°C vs. >100 ppm/°C for Zeners) or adjustable output voltage is needed. It requires only two external resistors to set the output, and its 3-pin functional equivalence (anode, cathode, reference) simplifies retrofitting into legacy layouts originally designed for TO-92 Zeners.
What is the maximum cathode voltage rating for the LM431BCMX?
The LM431BCMX supports a maximum cathode voltage of 36 V, as defined in its Absolute Maximum Ratings. This allows use in higher-voltage applications such as 24 V industrial supplies or 32 V PoE-powered systems - exceeding the 30 V limit of alternatives like AS431ASTU and enabling broader design flexibility than standard 20 V Zeners.
How does the LM431BCMX achieve temperature stability?
The LM431BCMX integrates a temperature-compensated bandgap reference and matched transistor pair within its die, ensuring the reference voltage remains stable across 0°C to 70°C. Its average temperature coefficient is 50 ppm/°C, and total VREF deviation is guaranteed ≤±17 mV over the full range - achieved through on-chip curvature correction, not external compensation components.
Is the LM431BCMX pin-compatible with other LM431 variants?
Yes, all LM431 variants in SOIC-8 (e.g., LM431ACMX/NOPB, LM431AIMX/NOPB) share identical pinout and footprint with the LM431BCMX. Differences lie in reference voltage tolerance (A = ±2%, B = ±0.5%, C = ±1%), temperature grade (commercial vs. industrial), and electrical specs - allowing drop-in substitution where those parameters meet design requirements.
LM431BCMX Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- 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:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
LM431BCMX FAQ
1.How can I place an order for LM431BCMX through Aetrix?
Please submit a Request for Quotation (RFQ) for LM431BCMX 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 LM431BCMX reliable?
The price and inventory of LM431BCMX are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM431BCMX is usually 5 days.
3.What payment methods are accepted for LM431BCMX?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM431BCMX transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM431BCMX?
LM431BCMX orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM431BCMX 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 LM431BCMX?
For technical support, including LM431BCMX datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM431BCMX requirements.
6.How does Aetrix verify that LM431BCMX is sourced from the original manufacturer or authorized distributors?
All LM431BCMX 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 LM431BCMX meets industry standards.
7.What is the process for return or replacement of LM431BCMX?
All LM431BCMX units undergo pre-shipment inspection (PSI). If there is an issue with LM431BCMX, 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 LM431BCMX part is unused and in its original packaging.
Return procedure for LM431BCMX:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM431BCMX 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…
