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Texas Instruments LM2671MX-12
- Part No.:
- LM2671MX-12
- Manufacturer:
- Texas Instruments
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LM2671MX-12.pdf
- Description:
- IC REG BUCK 12V 500MA 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,833
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Product details
Overview
LM2671MX-12 from National Semiconductor is a monolithic 500mA step-down (buck) DC-DC voltage regulator with fixed 12V output, 260 kHz fixed-frequency switching, 0.25Ω DMOS output switch, ±1.5% output voltage tolerance over line/load/temperature, and wide 8V–40V input range. It delivers >94% efficiency at 24VIN/500mA and integrates soft-start, frequency synchronization, thermal shutdown, and current limiting for industrial power conversion.
For engineers reviewing the LM2671MX-12 datasheet, LM2671MX-12 pinout, LM2671MX-12 application, or LM2671MX-12 equivalent, this page provides verified technical context, package-specific design meaning, real-world application constraints, and validated alternative options for buck converter design in embedded power supplies.
Technical Context
The LM2671MX-12 implements a synchronous-buck topology using an internal DMOS power switch and patented frequency compensation (U.S. Pat. Nos. 5,382,918 & 5,514,947), eliminating need for external compensation components. Its 260 kHz oscillator enables use of compact 47–100 μH inductors and low-ESR tantalum or ceramic output capacitors.
Operation requires only five external components: input capacitor, output capacitor, catch diode (Schottky), inductor, and boost capacitor. The device supports TTL-compatible shutdown (50 μA standby), soft-start via external capacitor, and external frequency synchronization up to 400 kHz - all while maintaining guaranteed 500mA load current across −40°C to +125°C junction temperature.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 12V ±1.5% over 15V–40V input and 20mA–500mA load - ensures stable rail for 12V logic, analog sensors, or intermediate bus regulation. |
| Switching Frequency | 260 kHz (±10%) - enables use of standard off-the-shelf 47–68 μH inductors and reduces EMI compared to lower-frequency alternatives. |
| Efficiency | 94% typical at VIN = 24V, IOUT = 500mA - minimizes thermal stress; PCB copper traces suffice as heat sink without external heatsink. |
| Input Voltage Range | 8V to 40V - supports unregulated 12V/24V industrial rails, automotive battery inputs (with transient protection), and telecom intermediate buses. |
| Output Switch RDS(ON) | 0.25Ω max - limits conduction loss to <125 mW at 500mA, enabling high efficiency without external MOSFETs. |
| Quiescent Current | 2.5 mA typical (12V version) - maintains low no-load power draw in always-on systems; drops to 50 μA in shutdown mode. |
| Protection Features | Thermal shutdown + cycle-by-cycle current limit - prevents damage during overload, short-circuit, or ambient overheating without external circuitry. |
Pinout & Package
LM2671MX-12 is supplied in an 8-pin SOIC (SO-8) package (NSC MO8A/N08E), surface-mount, with exposed pad not electrically connected. Thermal resistance θJA = 105°C/W with ~1 in² copper pour.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (VIN) | Input Power Supply | Accepts 8–40V DC; requires ≥22 μF low-ESR tantalum or aluminum electrolytic bypass capacitor placed within 5 mm. |
| 2 (GND) | Power Ground | Primary return path for switch current and control circuitry; must connect to large copper plane for thermal and noise performance. |
| 3 (SYNC) | Frequency Synchronization Input | Accepts external 400 kHz square wave to synchronize switching; open or grounded for internal 260 kHz operation. |
| 4 (SW) | Switch Node | Drives external catch diode and inductor; high dv/dt node requiring short trace routing and ground shielding. |
| 5 (FB) | Feedback Input (N/A for fixed-output) | Internally connected to 12V divider; not accessible - no external resistor network required for LM2671MX-12. |
| 6 (ON/OFF) | Enable/Shutdown Control | TTL-compatible: <0.8V = shutdown (50 μA IQ), >2.0V = active; pull-up to VIN recommended for default-on operation. |
| 7 (BOOST) | Bootstrap Capacitor Connection | Requires 0.01 μF ceramic capacitor between SW and BOOST to drive internal high-side gate driver fully. |
| 8 (VOUT) | Regulated Output | Delivers 12V ±1.5% to load; requires ≥47 μF low-ESR output capacitor (e.g., Sprague 594D or AVX TPS series). |
Key Features
| Feature | Design Value |
|---|---|
| Patented Internal Compensation | Eliminates external compensation network - reduces BOM count and layout sensitivity while ensuring stability across all operating conditions. |
| Soft-Start Function | Controlled ramp-up via external CSS capacitor (e.g., 0.1 μF → ~10 ms start time) - prevents inrush current and output overshoot into light/no-load conditions. |
| Frequency Synchronization | Accepts external clock up to 400 kHz - enables multi-regulator phase alignment and EMI reduction in dense PCB layouts. |
| Standard Inductor Compatibility | Validated with off-the-shelf 47 μH inductors (e.g., Sumida RCR110D-470L, Coilcraft DO3308-473) - accelerates design and avoids custom magnetics. |
| Robust Protection Suite | Integrated thermal shutdown + current limit + undervoltage lockout - ensures safe operation under fault conditions without external monitoring ICs. |
Applications
| Industrial PLC Power Supply | Automotive Body Control Module |
|---|---|
|
Use Scenario: Converting 24V vehicle battery to stable 12V for microcontroller, CAN transceiver, and sensor interfaces in harsh environments. IC Role / Device Role / Timing Role: Primary buck regulator providing isolated, ripple-controlled 12V rail with thermal and short-circuit resilience. Use Value: 94% efficiency minimizes heat buildup in sealed enclosures; 8V–40V input range accommodates cold-crank (6.5V) and load-dump (40V) transients per ISO 7637-2. |
Use Scenario: Generating clean 12V supply for infotainment head unit logic from noisy 12V battery bus. IC Role / Device Role / Timing Role: Intermediate step-down stage before LDO post-regulation, reducing dropout and thermal load on downstream regulators. Use Value: 260 kHz switching allows small 47 μH inductor and 47 μF tantalum capacitor - saving board space vs. linear solutions or lower-frequency buck converters. |
| Industrial Sensor Transmitter | Point-of-Load Converter for FPGA I/O |
|
Use Scenario: Powering 4–20 mA loop-powered sensors and signal conditioning circuitry in factory automation systems. IC Role / Device Role / Timing Role: High-efficiency pre-regulator delivering 12V to op-amps, ADCs, and isolators with minimal self-heating. Use Value: ±1.5% output tolerance ensures accurate sensor excitation and reference voltage stability; soft-start prevents current surges during hot-plug events. |
Use Scenario: Providing 12V auxiliary rail to FPGA configuration memory, transceivers, and I/O banks in telecom base station cards. IC Role / Device Role / Timing Role: Dedicated buck converter for non-core power domain, decoupled from main 3.3V/1.2V rails. Use Value: SYNC pin enables synchronization with system clock to avoid beat frequencies; integrated current limit protects against FPGA I/O short circuits. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2672MX-12 | Pin-compatible upgrade with improved efficiency (95% vs. 94%), lower quiescent current (1.5 mA vs. 2.5 mA), and extended input range (6.5V–40V vs. 8V–40V). | Supports cold-crank down to 6.5V - suitable for automotive applications where LM2671MX-12 may drop out below 8V. | Select LM2672MX-12 when cold-crank robustness or marginally lower no-load power is critical; same PCB layout applies. |
| TPS54318RTER | 3A synchronous buck with integrated high/low-side FETs, 2.95V–6V input, and adjustable output - not pin- or functionally compatible. | Designed for low-input, high-current applications (e.g., 5V→3.3V PoL); requires redesign for 12V fixed output and 24V input. | Choose TPS54318RTER only if upgrading to higher current, lower input voltage, or synchronous architecture - full schematic and layout revision needed. |
Compared with LM2671MX-12, LM2672MX-12 offers enhanced cold-crank capability and efficiency with zero layout change, while TPS54318RTER targets fundamentally different input/output requirements and demands complete re-design - making LM2672MX-12 the preferred drop-in upgrade path.
Availability
LM2671MX-12 is available at Aetrix Electronics and suitable for industrial PLC power supplies, automotive body control modules, sensor transmitters, and FPGA point-of-load applications requiring stable component supply, long-term lifecycle support, and consistent parametric performance.
Supply support for LM2671MX-12 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
National Semiconductor (now part of Texas Instruments) specialized in high-performance analog and power management ICs, with a legacy of robust, application-ready power solutions for industrial and automotive markets.
The LM2671 series was designed as a SIMPLE SWITCHER® solution to simplify buck converter implementation - targeting engineers needing reliable, low-component-count DC-DC conversion without complex compensation or layout tuning.
FAQ
What is the maximum input voltage rating for the LM2671MX-12?
The absolute maximum input voltage for the LM2671MX-12 is 45V, but the recommended operating range is 8V to 40V. Operation above 40V risks exceeding internal device stress limits, while input below 8V may cause dropout under full 500mA load. For automotive cold-crank scenarios down to 6.5V, consider the LM2672MX-12 as a direct upgrade. The LM2671MX-12 datasheet specifies guaranteed performance only within the 8V–40V range.
Does the LM2671MX-12 require an external feedback resistor network?
No - the LM2671MX-12 is a fixed-output variant with internal resistor divider set to 12V; the FB pin is not accessible and must remain unconnected. Unlike the adjustable LM2671MX-ADJ, no external R1/R2 network is needed. Attempting to modify feedback will disrupt regulation and void specified output accuracy. All design documentation for LM2671MX-12 assumes open-circuit FB connection.
Can the LM2671MX-12 be synchronized to an external clock?
Yes - the SYNC pin (Pin 3) accepts an external square wave up to 400 kHz to synchronize switching. A 1 kΩ resistor and 100 pF capacitor form the recommended RC filter at the SYNC input. When left unconnected or grounded, the LM2671MX-12 operates at its internal 260 kHz frequency. Synchronization helps reduce EMI in multi-rail systems and enables phase interleaving in parallel configurations.
What type of catch diode is recommended for the LM2671MX-12?
A Schottky diode rated ≥3A and ≥50V reverse voltage is recommended - e.g., IR 30WQ05F (3A, 50V) or equivalent. The diode must be placed adjacent to the LM2671MX-12 with minimal trace length to minimize ringing and losses. Fast recovery and low forward voltage (<0.5V) are critical for maintaining >94% efficiency. Standard PN diodes are unsuitable due to excessive reverse recovery losses.
Is thermal derating required for the LM2671MX-12 at 500mA continuous load?
Not under typical PCB conditions - the LM2671MX-12 delivers 500mA continuously with only PCB copper as heatsink when using ≥1 in² of 2-oz copper connected to the GND pin. Junction temperature remains below 125°C at 24VIN/500mA with θJA = 105°C/W. However, in enclosed or high-ambient (>70°C) environments, verify actual board temperature with IR imaging or thermocouple measurement near the IC body.
LM2671MX-12 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- SIMPLE SWITCHER®
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 6.5V
- Voltage - Input (Max):
- 40V
- Voltage - Output (Min/Fixed):
- 12V
- Voltage - Output (Max):
- -
- Current - Output:
- 500mA
- Frequency - Switching:
- 260kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
LM2671MX-12 FAQ
1.How can I place an order for LM2671MX-12 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2671MX-12 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 LM2671MX-12 reliable?
The price and inventory of LM2671MX-12 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2671MX-12 is usually 5 days.
3.What payment methods are accepted for LM2671MX-12?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2671MX-12 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2671MX-12?
LM2671MX-12 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2671MX-12 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 LM2671MX-12?
For technical support, including LM2671MX-12 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2671MX-12 requirements.
6.How does Aetrix verify that LM2671MX-12 is sourced from the original manufacturer or authorized distributors?
All LM2671MX-12 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 LM2671MX-12 meets industry standards.
7.What is the process for return or replacement of LM2671MX-12?
All LM2671MX-12 units undergo pre-shipment inspection (PSI). If there is an issue with LM2671MX-12, 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 LM2671MX-12 part is unused and in its original packaging.
Return procedure for LM2671MX-12:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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