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Texas Instruments LM2671N-3.3
- Part No.:
- LM2671N-3.3
- Manufacturer:
- Texas Instruments
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
LM2671N-3.3.pdf
- Description:
- IC REG BUCK 3.3V 500MA 8PDIP
- Quantity:
- Payment:
- Shipping:
Inventory:3,873
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Product details
Overview
LM2671N-3.3 from National Semiconductor is a monolithic 500mA step-down (buck) DC-DC switching regulator in an 8-pin DIP package, delivering a fixed 3.3V output with ±1.5% tolerance over line and load, 260 kHz fixed-frequency operation, and 0.25Ω DMOS switch. It enables high-efficiency (>90%) power conversion in industrial control, embedded systems, and point-of-load regulation where compact size and thermal simplicity are critical.
For engineers reviewing the LM2671N-3.3 datasheet, LM2671N-3.3 pinout, LM2671N-3.3 application, or LM2671N-3.3 equivalent, key selection considerations include its 8V–40V input range, TTL-compatible shutdown, soft-start capability, thermal shutdown protection, and compatibility with standard off-the-shelf inductors and Schottky diodes - all supporting rapid, low-risk buck converter design without external compensation.
Technical Context
The LM2671N-3.3 integrates a 0.25Ω DMOS power switch, internal 260 kHz oscillator, and patented frequency compensation, eliminating need for external loop compensation components. Its architecture supports continuous-mode operation with up to 95% duty cycle and includes built-in current limiting and thermal shutdown for fault robustness.
It features a dedicated ON/OFF pin with 1.4V threshold and 50 μA standby current, a feedback reference of 1.21V (for adjustable variants), and a soft-start function controlled via external capacitor - all implemented within a single monolithic LDMOS process IC optimized for reliability under wide input voltage and temperature ranges (−40°C to +125°C).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3V ±1.5% over full line/load/temperature range - ensures stable logic supply for 3.3V microcontrollers and FPGAs without post-regulation. |
| Max Output Current | 500mA continuous - sufficient to power multiple digital ICs or small subsystems from a single regulator stage. |
| Input Voltage Range | 6.5V to 40V - supports wide-input industrial, automotive, and telecom power rails without pre-regulation. |
| Switching Frequency | 260 kHz (±10%) - enables use of smaller, cost-effective inductors and capacitors versus lower-frequency alternatives. |
| Efficiency | Up to 86% at VIN = 12V, IOUT = 500mA - minimizes heat generation; PCB copper traces serve as sole heatsink. |
| Quiescent Current | 2.5 mA typical operating, 50 μA standby - reduces system power loss during sleep or idle modes. |
| Thermal Resistance | 95°C/W (Junction-to-Ambient, N package) - defines thermal performance baseline for layout-driven cooling. |
Pinout & Package
LM2671N-3.3 is housed in an 8-pin plastic dual in-line package (DIP), through-hole mountable, with standard MO8A/N08E footprint. Thermal resistance is specified at 95°C/W with ~1 in² copper area around leads.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (VIN) | Input Power Supply | Accepts 6.5V–40V DC; requires local 22μF tantalum bypass capacitor to suppress transients. |
| 2 (GND) | Power Ground | Common return for input/output paths and IC substrate; must connect to low-impedance ground plane. |
| 3 (SYNC) | Frequency Synchronization Input | Allows external clock injection up to 400 kHz; unused pin should be grounded to avoid noise coupling. |
| 4 (ON/OFF) | Enable/Shutdown Control | TTL-compatible input; <1.4V disables regulator, reducing quiescent current to 50 μA. |
| 5 (FB) | Feedback Input (Not used in fixed-output version) | Internally connected to output divider; left unconnected in LM2671N-3.3 - no external resistor network required. |
| 6 (SW) | Switch Node | Drives external catch diode and inductor; high dv/dt node requiring short, low-inductance routing. |
| 7 (BOOST) | Bootstrap Capacitor Terminal | Connects to 0.01μF ceramic capacitor between SW and BOOST to gate-drive internal DMOS switch fully. |
| 8 (VOUT) | Regulated Output | Delivers fixed 3.3V; requires 47μF tantalum output capacitor with ≤0.1Ω ESR for stability and ripple suppression. |
Key Features
| Feature | Design Value |
|---|---|
| Patented internal frequency compensation | Eliminates need for external compensation network - simplifies design and improves production yield. |
| Soft-start function | Controlled by external capacitor on SS pin; prevents inrush current and output overshoot during power-up. |
| Thermal shutdown & current limit | Protects device under overload or ambient overheating; automatically recovers when conditions normalize. |
| 260 kHz fixed-frequency oscillator | Enables predictable EMI profile and consistent filter component sizing across designs. |
| Standard inductor compatibility | Validated with off-the-shelf 47–150 μH inductors from Schott, Renco, Pulse, and Coilcraft - accelerates BOM sourcing. |
Applications
| Industrial PLC I/O Module Power | Embedded Microcontroller Core Supply |
|---|---|
|
Use Scenario: Providing clean, regulated 3.3V power to isolated digital I/O banks in programmable logic controllers operating from 24V DC field buses. IC Role / Device Role / Timing Role: Primary step-down regulator converting 24V bus to 3.3V logic rail; operates continuously with 500mA peak demand per module. Use Value: High efficiency (>90%) minimizes heat buildup in sealed enclosures; wide input range accommodates bus voltage fluctuations without dropout. |
Use Scenario: Powering ARM Cortex-M or RISC-V microcontrollers and associated peripherals (SPI flash, sensors) in battery-backed edge nodes. IC Role / Device Role / Timing Role: Main system regulator delivering stable 3.3V core voltage; enabled/disabled via MCU GPIO for low-power sleep states. Use Value: 50 μA standby current extends battery life; soft-start prevents brown-out during wake-up transitions. |
| Telecom Line Card Pre-Regulator | Test Equipment Digital Subsystem Supply |
|
Use Scenario: Generating intermediate 3.3V rail from −48V telecom supply (via intermediate 12V stage) for FPGA configuration and interface logic. IC Role / Device Role / Timing Role: Efficient pre-regulator stage feeding linear regulators; handles transient loads from burst-mode data processing. Use Value: 260 kHz switching allows compact LC filters; thermal shutdown protects against sustained overloads during firmware updates. |
Use Scenario: Supplying precision analog-to-digital converters and high-speed serial interfaces in automated test equipment with strict noise budgets. IC Role / Device Role / Timing Role: Dedicated low-noise 3.3V source; synchronized to system clock via SYNC pin to reduce beat-frequency interference. Use Value: Fixed-frequency operation enables deterministic EMI filtering; DIP package facilitates prototyping and rework on lab boards. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2576-3.3 | 3A output current, 52 kHz switching frequency, larger external components required. | Better suited for higher-current loads but less efficient at light loads due to lower frequency. | Select LM2576-3.3 only if >500mA output or higher thermal margin is needed; LM2671N-3.3 offers superior size/efficiency trade-off below 500mA. |
| TPS5430DDAR | 3A output, 500 kHz switching, SO-8 package, requires external compensation. | Higher integration density and efficiency, but demands more design effort and layout sensitivity. | Choose TPS5430DDAR for space-constrained PCBs needing >500mA; LM2671N-3.3 remains optimal for quick-turn, low-risk DIP-based designs with moderate current needs. |
Compared with LM2576-3.3 and TPS5430DDAR, the LM2671N-3.3 delivers best-in-class ease-of-use for 500mA applications - combining fixed compensation, DIP prototyping support, and proven thermal behavior - while avoiding the complexity of higher-current or higher-frequency alternatives.
Availability
LM2671N-3.3 is available at Aetrix Electronics and suitable for industrial automation, embedded computing, and test equipment applications requiring stable component supply, long-term obsolescence management, and traceable sourcing.
Supply support for LM2671N-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 was a U.S.-based semiconductor company specializing in analog and power management ICs, acquired by Texas Instruments in 2011. Its SIMPLE SWITCHER® portfolio defined industry standards for easy-to-use switching regulators.
The LM2671 series was designed specifically for engineers needing fast, reliable buck converter implementation without compensation expertise - targeting industrial, telecom, and embedded systems where time-to-market and thermal simplicity are critical.
FAQ
What is the maximum input voltage rating for the LM2671N-3.3?
The absolute maximum input voltage for the LM2671N-3.3 is 45V, but the recommended operating range is 6.5V to 40V. Exceeding 40V may compromise long-term reliability or trigger overvoltage protection mechanisms not explicitly documented in the datasheet. Always maintain input transients within this window using appropriate front-end clamping or filtering.
Does the LM2671N-3.3 require external compensation components?
No, the LM2671N-3.3 does not require external compensation components. It incorporates patented internal frequency compensation (U.S. Patents 5,382,918 and 5,514,947), enabling stable operation with only five external components: input capacitor, output capacitor, catch diode, inductor, and boost capacitor.
Can the LM2671N-3.3 be synchronized to an external clock?
Yes, the LM2671N-3.3 supports external synchronization via its SYNC pin (Pin 3). Applying a square wave signal with ≥3V peak-to-peak amplitude and frequency up to 400 kHz allows precise timing alignment with other system clocks - useful for EMI reduction and multi-rail coordination in complex power architectures.
What is the thermal performance of the LM2671N-3.3 in its DIP package?
The LM2671N-3.3 has a junction-to-ambient thermal resistance (θJA) of 95°C/W when mounted on a PCB with approximately 1 in² of copper surrounding its leads. This value decreases with additional copper area or thermal vias, enabling reliable 500mA operation without heatsinks under typical ambient conditions.
Is the LM2671N-3.3 pin-compatible with other members of the LM2671 family?
Yes, all LM2671 variants - including LM2671N-3.3, LM2671N-5.0, LM2671N-12, and LM2671N-ADJ - share identical 8-pin DIP pinouts and package dimensions. Only the internal feedback network differs; external circuitry (inductor, diode, capacitors) remains interchangeable across fixed-output versions.
LM2671N-3.3 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- SIMPLE SWITCHER®
- Package/Case:
- 8-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- 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:
- Through Hole
- Supplier Device Package:
- 8-PDIP
LM2671N-3.3 FAQ
1.How can I place an order for LM2671N-3.3 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2671N-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 LM2671N-3.3 reliable?
The price and inventory of LM2671N-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 LM2671N-3.3 is usually 5 days.
3.What payment methods are accepted for LM2671N-3.3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2671N-3.3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2671N-3.3?
LM2671N-3.3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2671N-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 LM2671N-3.3?
For technical support, including LM2671N-3.3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2671N-3.3 requirements.
6.How does Aetrix verify that LM2671N-3.3 is sourced from the original manufacturer or authorized distributors?
All LM2671N-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 LM2671N-3.3 meets industry standards.
7.What is the process for return or replacement of LM2671N-3.3?
All LM2671N-3.3 units undergo pre-shipment inspection (PSI). If there is an issue with LM2671N-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 LM2671N-3.3 part is unused and in its original packaging.
Return procedure for LM2671N-3.3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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