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Texas Instruments LM2671M-3.3
- Part No.:
- LM2671M-3.3
- Manufacturer:
- Texas Instruments
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LM2671M-3.3.pdf
- Description:
- IC REG BUCK 3.3V 500MA 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,882
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Product details
Overview
LM2671M-3.3 from National Semiconductor is a monolithic 500mA step-down (buck) DC-DC switching regulator in SO-8 package, delivering fixed 3.3V output with ±1.5% tolerance over line/load/temperature, 260 kHz fixed-frequency operation, and integrated 0.25Ω DMOS switch. It enables high-efficiency (>90%) power conversion in industrial control, telecom power supplies, and embedded systems requiring stable low-voltage rails.
For engineers reviewing the LM2671M-3.3 datasheet, LM2671M-3.3 pinout, LM2671M-3.3 application, or LM2671M-3.3 equivalent, key selection criteria include input voltage range (6.5–40V), guaranteed 500mA load capability, thermal shutdown protection, TTL-compatible shutdown pin, and soft-start functionality - all critical for robust offline-to-3.3V conversion without external compensation.
Technical Context
The LM2671M-3.3 implements a current-mode buck topology with internal frequency compensation (U.S. Pat. Nos. 5,382,918 & 5,514,947), enabling stable operation using only five external components. Its 260 kHz oscillator allows compact LC filter sizing while maintaining EMI control through fixed-frequency switching.
It integrates a 0.25Ω RDS(ON) DMOS power switch, feedback comparator with 1.21V reference, soft-start circuit (0.63V threshold), and synchronization input for system-level clock alignment. Protection includes cycle-by-cycle current limiting and thermal shutdown, ensuring fault resilience in unattended operation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3V ±1.5% over full operating temperature (−40°C to +125°C) and load (20–500 mA), enabling direct replacement of linear regulators without feedback tuning. |
| Max Output Current | Guaranteed 500mA continuous load current - sufficient to power microcontrollers, FPGAs, and interface ICs without derating at ambient ≤85°C. |
| Input Voltage Range | 6.5V to 40V DC - supports wide-input industrial and automotive battery-fed applications, including 12V/24V nominal systems with transients. |
| Switching Frequency | 260 kHz (±10%), fixed internal oscillator - balances efficiency and component size; allows use of standard off-the-shelf 47–100 μH inductors and low-ESR tantalum capacitors. |
| Efficiency | 86% typical at VIN = 12V, IOUT = 500mA - reduces thermal load on PCB copper traces, eliminating need for heatsinks in most designs. |
| Shutdown Current | 50 μA typical standby quiescent current when ON/OFF pin is low - enables low-power sleep modes in battery-backed or energy-conscious systems. |
| Thermal Protection | Internal thermal shutdown activates at TJ ≥ +150°C - prevents permanent damage during overload or poor heatsinking conditions. |
Pinout & Package
LM2671M-3.3 is housed in an 8-pin SOIC (SO-8) package per NSC drawing MO8A/N08E, 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 6.5–40V DC; requires local 22μF tantalum bypass capacitor to suppress input ripple and transient spikes. |
| 2 (GND) | Power Ground | Main return path for switch current and control circuitry; must be tied to low-impedance ground plane adjacent to IC. |
| 3 (SYNC) | Frequency Synchronization Input | Accepts external 400 kHz square wave to lock switching frequency; open or grounded for internal 260 kHz operation. |
| 4 (FB) | Feedback Input (N/A for fixed 3.3V) | Internally connected to 3.3V output divider; not accessible - no external resistor network required. |
| 5 (SW) | Switch Node | Drives external catch diode and inductor; carries high dI/dt; must be routed short and wide to minimize EMI and voltage spikes. |
| 6 (BOOST) | Bootstrap Capacitor Terminal | Connects 0.01μF ceramic capacitor between SW and BOOST to generate gate drive voltage for internal DMOS switch. |
| 7 (ON/OFF) | TTL-Compatible Enable/Shutdown | Logic-low (<0.8V) disables regulator and reduces IQ to 50 μA; logic-high (>2.0V) enables normal operation. |
| 8 (VOUT) | Regulated Output | Delivers fixed 3.3V; requires 47–100μF low-ESR output capacitor (e.g., Sprague 594D or AVX TPS series) for stability and transient response. |
Key Features
| Feature | Design Value |
|---|---|
| Patented Internal Compensation | Eliminates need for external compensation network - simplifies design, reduces BOM count, and ensures stability across all operating conditions. |
| Integrated 0.25Ω DMOS Switch | Reduces conduction losses and eliminates discrete MOSFET selection; supports full 500mA load without external switch or driver. |
| Soft-Start Function | Controls output ramp-up via internal 4.5μA current source charging external CSS capacitor - prevents inrush current and output overshoot. |
| Current Limit & Thermal Shutdown | Provides cycle-by-cycle peak current limiting (0.62–1.2A) and automatic shutdown at 150°C junction - protects against short-circuit and overheating faults. |
| External Frequency Sync | Allows synchronization to system clock up to 400 kHz - essential for noise-sensitive applications and multi-regulator phase alignment. |
Applications
| Industrial PLC I/O Module Power | Telecom Line Card Pre-Regulator |
|---|---|
Use Scenario: Powers isolated digital I/O channels and analog sensor interfaces in programmable logic controllers operating from 24V DC bus with 40V transients. IC Role / Device Role / Timing Role: Primary buck converter generating clean 3.3V rail for microcontroller, CAN transceiver, and ADC reference. Use Value: 86% efficiency at 500mA minimizes heat buildup in sealed enclosures; 40V max input withstands load-dump events without external TVS. |
Use Scenario: Generates intermediate 3.3V supply from 48V telecom battery backup before LDO post-regulation for FPGA and SerDes cores. IC Role / Device Role / Timing Role: High-current pre-regulator reducing voltage differential across downstream linear regulators to improve overall system efficiency. Use Value: Fixed 3.3V output eliminates feedback resistor errors; 260 kHz switching enables small 47μH inductor footprint compatible with dense line card layouts. |
| Embedded Network Router Core Logic | Automotive Infotainment Display Backlight Supply |
Use Scenario: Supplies 3.3V to ARM-based SoC, Ethernet PHY, and DDR memory in fanless enterprise routers with strict thermal limits. IC Role / Device Role / Timing Role: Main system power IC converting 12V vehicle or PoE-derived input to processor core voltage domain. Use Value: 50μA shutdown current extends battery runtime during deep-sleep states; thermal shutdown prevents field failures under sustained CPU load. |
Use Scenario: Powers LED driver ICs and display controller in automotive head units where input varies from 9–16V battery with cold-crank dips to 6.5V. IC Role / Device Role / Timing Role: Buck regulator sustaining regulated 3.3V during cranking, feeding backlight dimming circuitry and touch controller. Use Value: 6.5V minimum input ensures operation down to battery voltages during engine start; ±1.5% output tolerance maintains consistent LED brightness calibration. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2672M-3.3 | Higher efficiency (90% typ. at 12V/500mA), improved light-load quiescent current (2.5mA vs. 2.5mA), same pinout and package. | Preferred for new designs targeting >90% efficiency or tighter thermal budgets; identical layout compatibility. | Select LM2672M-3.3 when optimizing for peak efficiency or lower thermal rise; LM2671M-3.3 remains valid for cost-sensitive legacy replacements. |
| TPS5430DR | 3.0A output capability, 500kHz switching, external compensation, wider input (5.5–36V), no integrated soft-start. | Suitable for higher-current or faster-transient applications; requires additional design effort for loop compensation and startup control. | Choose TPS5430DR only if >500mA load or <1μs transient response is required; LM2671M-3.3 offers simpler implementation for standard 3.3V/500mA needs. |
Compared with LM2672M-3.3, the LM2671M-3.3 trades 4% peak efficiency for broader input range (6.5–40V vs. 5.5–36V) and proven field reliability; versus TPS5430DR, it delivers plug-and-play simplicity at half the output current, avoiding compensation design risk.
Availability
LM2671M-3.3 is available at Aetrix Electronics and suitable for industrial automation, telecom infrastructure, and automotive infotainment systems requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LM2671M-3.3 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 leadership in switching regulator technology and application-focused design tools.
The LM2671 series was designed specifically for simple, high-efficiency DC-DC conversion in space-constrained industrial and communications equipment - emphasizing minimal external parts, internal protection, and ease of use via LM267X Made Simple software.
FAQ
What is the maximum input voltage rating for the LM2671M-3.3?
The absolute maximum input voltage for the LM2671M-3.3 is 45V, but the recommended operating range is 6.5V to 40V DC. Exceeding 40V may trigger internal protection or reduce reliability; operation at 40V is validated in datasheet electrical characteristics with full 500mA load capability and thermal margin.
Does the LM2671M-3.3 require external compensation components?
No, the LM2671M-3.3 incorporates patented internal frequency compensation (U.S. Pat. Nos. 5,382,918 and 5,514,947), eliminating the need for external compensation networks. This allows stable operation with only five external components: input capacitor, output capacitor, catch diode, inductor, and boost capacitor.
Can the LM2671M-3.3 be synchronized to an external clock?
Yes, the LM2671M-3.3 supports external frequency synchronization via Pin 3 (SYNC). Applying a 400 kHz square wave with ≥3V p-p to this pin locks the internal oscillator, enabling noise reduction in sensitive systems and phase alignment with other switching regulators in multi-rail designs.
What is the purpose of the BOOST pin on the LM2671M-3.3?
The BOOST pin on the LM2671M-3.3 connects to a 0.01μF ceramic capacitor between SW and BOOST to generate the gate drive voltage for the internal DMOS switch. This bootstrap circuit ensures full enhancement of the high-side switch, maintaining low RDS(ON) and high efficiency across the input range.
Is the LM2671M-3.3 RoHS compliant and lead-free?
Yes, the LM2671M-3.3 manufactured after 2006 complies with RoHS Directive 2002/95/EC and is lead-free. The SO-8 package uses matte tin lead finish, and the device meets JEDEC J-STD-020 moisture sensitivity level 3 (MSL-3) for standard surface-mount assembly processes.
LM2671M-3.3 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):
- 3.3V
- 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
LM2671M-3.3 FAQ
1.How can I place an order for LM2671M-3.3 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2671M-3.3 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 LM2671M-3.3 reliable?
The price and inventory of LM2671M-3.3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2671M-3.3 is usually 5 days.
3.What payment methods are accepted for LM2671M-3.3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2671M-3.3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2671M-3.3?
LM2671M-3.3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2671M-3.3 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 LM2671M-3.3?
For technical support, including LM2671M-3.3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2671M-3.3 requirements.
6.How does Aetrix verify that LM2671M-3.3 is sourced from the original manufacturer or authorized distributors?
All LM2671M-3.3 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 LM2671M-3.3 meets industry standards.
7.What is the process for return or replacement of LM2671M-3.3?
All LM2671M-3.3 units undergo pre-shipment inspection (PSI). If there is an issue with LM2671M-3.3, 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 LM2671M-3.3 part is unused and in its original packaging.
Return procedure for LM2671M-3.3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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