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Texas Instruments LM2672N-3.3
- Part No.:
- LM2672N-3.3
- Manufacturer:
- Texas Instruments
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
LM2672N-3.3.pdf
- Description:
- IC REG BUCK 3.3V 1A 8PDIP
- Quantity:
- Payment:
- Shipping:
Inventory:2,133
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Product details
Overview
LM2672N-3.3 from National Semiconductor is a monolithic 1A 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 >90% efficiency at 12V input/1A load. It integrates a 0.25Ω DMOS power switch, soft-start, TTL-compatible shutdown, and thermal/current protection for industrial power rails.
For engineers reviewing the LM2672N-3.3 datasheet, LM2672N-3.3 pinout, LM2672N-3.3 application, or LM2672N-3.3 equivalent, key selection criteria include input voltage range (6.5–40V), guaranteed 1A output current, standby current (50 μA), oscillator frequency stability (±10%), and compatibility with standard off-the-shelf inductors and Schottky catch diodes.
Technical Context
The LM2672N-3.3 implements a synchronous-buck topology using an internal DMOS switch with 0.25Ω RDS(ON), driven by a fixed 260 kHz oscillator and patented internal frequency compensation. Its control architecture includes voltage-mode PWM with feedback via the FB pin referenced to 1.21V internal bandgap.
It supports external frequency synchronization (up to 400 kHz), soft-start via CSS pin (4.5 μA current source), and shutdown with 0.8–2.0V logic threshold. Protection features include cycle-by-cycle current limiting (1.25–2.2A), thermal shutdown, and under-voltage lockout on VIN.
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 mA–1A), enabling stable logic supply without external resistive divider. |
| Max Output Current | Guaranteed 1A continuous output current, supporting single-rail microcontroller or FPGA core supplies without derating at ambient ≤50°C. |
| Input Voltage Range | 6.5V to 40V DC, allowing direct use with unregulated 12V/24V industrial bus or automotive battery inputs after transient suppression. |
| Switching Frequency | 260 kHz fixed (±10%), enabling compact 22–68 μH inductor selection and predictable EMI filtering design per FCC Class B limits. |
| Efficiency | 86% typical at VIN = 12V, IOUT = 1A - reduces thermal load to PCB copper traces only, eliminating need for heatsinks in most layouts. |
| Quiescent Current | 2.5 mA typical operating IQ; 50 μA standby current during shutdown - critical for low-power wake-on-event systems. |
| Switch RDS(ON) | 0.25Ω typical - minimizes conduction loss and enables high efficiency even at lower input voltages (e.g., 8V → 3.3V). |
Pinout & Package
LM2672N-3.3 uses an 8-pin plastic dual in-line package (DIP), with through-hole mounting and 0.3" wide body. Thermal resistance θJA is 95°C/W with ~1 in² copper pour, suitable for moderate-power industrial boards.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (VIN) | Input Power Supply | Accepts 6.5–40V DC; requires local 22 μF tantalum bypass capacitor near pin to suppress transients. |
| 2 (GND) | Power Ground | Common return for input/output capacitors, inductor, and catch diode; must connect to low-impedance ground plane. |
| 3 (SYNC) | Frequency Synchronization Input | Accepts external 400 kHz square wave to override internal 260 kHz oscillator; enables multi-regulator noise cancellation. |
| 4 (FB) | Feedback Input (N/C for fixed versions) | No-connect for LM2672N-3.3; internally tied to 3.3V reference; not used in fixed-output configuration. |
| 5 (SW) | Switch Node | Drives external catch diode and inductor; switches between VIN and GND at 260 kHz; requires short, low-inductance routing. |
| 6 (BOOST) | Bootstrap Capacitor Terminal | Connects 0.01 μF ceramic capacitor between SW and BOOST to generate gate drive voltage for internal DMOS switch. |
| 7 (SS) | Soft-Start Timing Input | Controls startup ramp time via external capacitor; 4.5 μA current source charges CSS to 0.63V threshold for controlled VOUT rise. |
| 8 (ON/OFF) | Enable/Shutdown Control | TTL-compatible input: <0.8V disables regulator (50 μA standby); >2.0V enables; 1.4V typical threshold. |
Key Features
| Feature | Design Value |
|---|---|
| Patented internal frequency compensation | Eliminates need for external compensation network - simplifies layout and ensures stability with standard 22–68 μH inductors. |
| Integrated 0.25Ω DMOS power switch | Reduces component count and board space vs. controller+external MOSFET solutions; enables 1A output in DIP-8 footprint. |
| 260 kHz fixed-frequency operation | Enables predictable EMI filter design and consistent inductor sizing across designs; avoids audible noise in 20–200 kHz range. |
| TTL-compatible shutdown with 50 μA standby | Allows direct interfacing with microcontroller GPIOs; supports low-power sleep modes without auxiliary enable circuitry. |
| Thermal shutdown + current limit protection | Provides fault resilience during overload, short-circuit, or inadequate heatsinking - prevents catastrophic failure in field deployments. |
Applications
| Industrial PLC I/O Module Power | Automotive Body Control Unit (BCU) |
|---|---|
|
Use Scenario: Powering isolated 3.3V digital logic and CAN transceivers in DIN-rail mounted programmable logic controllers. IC Role / Device Role / Timing Role: Primary buck regulator converting 24V rail to clean, regulated 3.3V for microcontroller, ADC, and interface ICs. Use Value: 86% efficiency at 24V→3.3V/500mA reduces heat buildup in sealed enclosures; 40V max input withstands load-dump transients. |
Use Scenario: Generating 3.3V supply for infotainment MCU and sensor interfaces in 12V automotive systems. IC Role / Device Role / Timing Role: Step-down converter handling cold-crank (6.5V) to load-dump (40V) conditions while maintaining stable 3.3V output. Use Value: ±1.5% output tolerance ensures reliable operation of automotive-grade logic; 50 μA shutdown current meets ISO 16750 quiescent requirements. |
| Point-of-Load for FPGA Core Rails | Medical Diagnostic Equipment Power |
|
Use Scenario: Local regulation of 3.3V core voltage for Xilinx Spartan-6 or Intel MAX 10 FPGAs in test equipment. IC Role / Device Role / Timing Role: High-current (1A) point-of-load regulator placed adjacent to FPGA to minimize IR drop and noise coupling. Use Value: 1A capability supports FPGA configuration and active logic states; soft-start prevents inrush-induced brownout on shared 12V supply. |
Use Scenario: Providing isolated 3.3V supply for patient-monitoring microcontrollers and analog front-end sensors. IC Role / Device Role / Timing Role: Primary DC-DC stage converting medical-grade 24V DC supply to safety-isolated 3.3V logic rail. Use Value: Internal protection (thermal/current limit) enhances system reliability; fixed 3.3V eliminates calibration drift from resistor tolerances. |
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 | SO-8 surface-mount package; θJA = 105°C/W; identical electrical specs and pinout except for package. | Suitable for automated SMT assembly; requires reflow profile compatible with SO-8; less suited for prototyping or manual repair. | Select when volume production, board space constraints, or thermal management via PCB copper outweigh through-hole serviceability. |
| LM2576-3.3 | Lower 52 kHz switching frequency; higher RDS(ON) (0.35Ω); no SYNC or soft-start pins; 3A output rating. | Better low-frequency EMI performance; larger inductor/capacitor size; less efficient at light loads due to fixed frequency. | Choose for cost-sensitive, non-noise-critical applications where board area is less constrained and 3A headroom is needed. |
Compared with LM2672M-3.3, the LM2672N-3.3 offers easier hand-soldering and higher thermal performance in ambient-limited environments; versus LM2576-3.3, it delivers superior efficiency, smaller magnetics, and advanced features like synchronization - at the cost of higher complexity in EMI filtering.
Availability
LM2672N-3.3 is available at Aetrix Electronics and suitable for industrial automation, automotive electronics, and medical device power supplies requiring stable component supply, long-term lifecycle support, and traceable sourcing from authorized channels.
Supply support for LM2672N-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 a legacy of robust, application-ready power solutions for demanding environments.
The LM2672 series was designed specifically for simple, high-efficiency step-down conversion in industrial, automotive, and instrumentation systems - emphasizing ease of use, minimal external components, and built-in protection.
FAQ
What is the maximum input voltage rating for the LM2672N-3.3?
The absolute maximum input voltage for the LM2672N-3.3 is 45V, but the recommended operating range is 6.5V to 40V DC. Exceeding 40V risks violating the specified operating ratings and may trigger overvoltage stress on internal circuitry, especially the DMOS switch and bias networks. Always include transient voltage suppression if used in automotive or industrial settings with potential load-dump events.
Does the LM2672N-3.3 require an external feedback resistor network?
No, the LM2672N-3.3 does not require an external feedback resistor network. It is a fixed-output version with internal 3.3V regulation; the FB pin is internally connected and must remain unconnected (no external components). Only adjustable versions (e.g., LM2672N-ADJ) use external resistors to set VOUT.
Can the LM2672N-3.3 be synchronized to an external clock?
Yes, the LM2672N-3.3 supports external frequency synchronization via its SYNC pin (Pin 3). Applying a square wave with ≥3VPP and up to 400 kHz allows precise timing alignment with other switching regulators - reducing beat frequencies and simplifying EMI filter design in multi-rail systems.
What type of catch diode is recommended for the LM2672N-3.3?
A Schottky diode rated for ≥3.3A average current and ≥50V reverse voltage is recommended - such as the IR 30WQ05F (3.3A, 50V) cited in the datasheet. Schottky diodes minimize forward voltage drop and switching losses, directly improving efficiency and thermal performance compared to fast-recovery PN diodes.
Is the LM2672N-3.3 RoHS compliant?
The LM2672N-3.3 was originally released in April 2007, prior to full RoHS enforcement for legacy National Semiconductor products. While many units shipped post-2006 meet Pb-free requirements, official RoHS documentation is not provided for this specific DIP variant. For new designs requiring compliance, consider TI's LM2672MX-3.3 (SO-8, RoHS-compliant) or verify lot-specific certification with Aetrix Electronics.
LM2672N-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:
- 1A
- Frequency - Switching:
- 260kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 8-PDIP
LM2672N-3.3 FAQ
1.How can I place an order for LM2672N-3.3 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2672N-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 LM2672N-3.3 reliable?
The price and inventory of LM2672N-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 LM2672N-3.3 is usually 5 days.
3.What payment methods are accepted for LM2672N-3.3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2672N-3.3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2672N-3.3?
LM2672N-3.3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2672N-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 LM2672N-3.3?
For technical support, including LM2672N-3.3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2672N-3.3 requirements.
6.How does Aetrix verify that LM2672N-3.3 is sourced from the original manufacturer or authorized distributors?
All LM2672N-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 LM2672N-3.3 meets industry standards.
7.What is the process for return or replacement of LM2672N-3.3?
All LM2672N-3.3 units undergo pre-shipment inspection (PSI). If there is an issue with LM2672N-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 LM2672N-3.3 part is unused and in its original packaging.
Return procedure for LM2672N-3.3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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