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Texas Instruments LM2678SD-3.3
- Part No.:
- LM2678SD-3.3
- Manufacturer:
- Texas Instruments
- Package:
- 14-VDFN Exposed Pad
- Datasheet:
-
LM2678SD-3.3.pdf
- Description:
- IC REG BUCK 3.3V 5A 14VSON
- Quantity:
- Payment:
- Shipping:
Inventory:1,879
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Product details
Overview
LM2678SD-3.3 from Texas Instruments is a monolithic 5A step-down (buck) DC/DC voltage regulator with fixed 3.3V output, 260 kHz internal oscillator, 120 mΩ DMOS power switch, and wide 8V–40V input range-designed for high-efficiency power conversion in industrial and embedded systems requiring stable 3.3V rail generation.
For engineers reviewing the LM2678SD-3.3 datasheet, LM2678SD-3.3 pinout, LM2678SD-3.3 application, or LM2678SD-3.3 equivalent, key selection criteria include its ±2% output tolerance over full line/load/temperature, 50 μA standby current, thermal shutdown protection, and VSON-14 package compatibility with high-density PCB layouts.
Technical Context
The LM2678SD-3.3 implements a fixed-frequency pulse-width modulation (PWM) control architecture with an internal 260 kHz oscillator and cycle-by-cycle current limiting. Its integrated 120 mΩ DMOS switch enables continuous 5A output capability while maintaining >90% efficiency at typical operating points (e.g., 82% at VIN=12V, IOUT=5A).
It features internal feedback resistors for 3.3V regulation, ON/OFF control with 0.8V–2.0V threshold, and thermal shutdown activation at TJ ≥150°C. The device operates across −40°C to +125°C junction temperature and supports external boost capacitor (0.01 μF) for gate drive enhancement.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3V ±2% over −40°C to +125°C, 8V–40V input, 100mA–5A load - ensures stable logic supply without external resistor network. |
| Switching Frequency | 260 kHz ±11% - enables use of compact off-the-shelf inductors and reduces EMI compared to lower-frequency alternatives. |
| Efficiency | 82% at VIN=12V, IOUT=5A - delivers high power density with minimal thermal dissipation in space-constrained designs. |
| Current Limit | 7 A typical (6.1–8.75 A min/max) - provides robust short-circuit and overload protection without external sensing. |
| Standby Current | 50 μA max when ON/OFF pin = 0V - enables low-power system sleep modes without auxiliary regulators. |
| Thermal Resistance | θJA = 29°C/W (VSON-14 w/12 vias) - supports 5A operation with moderate PCB copper area, no heatsink required. |
| Input Voltage Range | 8V to 40V - accommodates unregulated industrial rails, battery stacks, and automotive-derived supplies. |
Pinout & Package
The LM2678SD-3.3 is housed in a 14-lead VSON (Very Small Outline No-lead) package (package code NHM0014A), featuring an exposed die attach pad (DAP) that must be connected to PCB ground for optimal thermal and electrical performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pin 2) | Power Input | Accepts 8V–40V unregulated input; requires local 10–100 μF input capacitor for stability and transient response. |
| VSW (Pins 1, 11, 12) | Switch Node | Drives external inductor; connects to boost capacitor (0.01 μF) and catch diode anode - high dv/dt node requiring tight layout. |
| GND (Pins 3, 4, 7, 13) | Ground Reference | Common return for power, control, and feedback; multiple pins reduce impedance and improve noise immunity. |
| ON/OFF (Pin 5) | Enable Control | Logic-level shutdown: <0.8V disables regulator (50 μA IQ); >2.0V enables - compatible with microcontroller GPIO. |
| FB (Pin 6) | Feedback Input | Internally tied to 3.3V divider; no external resistors needed - simplifies layout and eliminates trimming errors. |
| DAP (Exposed Pad) | Thermal & Electrical Ground | Mandatory connection to large PCB ground plane via ≥12 thermal vias - critical for achieving θJA = 29°C/W rating. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 120 mΩ DMOS Switch | Enables 5A continuous output without external MOSFETs or gate drivers - reduces BOM count and layout complexity. |
| Fixed 3.3V Output with ±2% Tolerance | Eliminates need for external feedback resistors and calibration - improves production yield and long-term stability. |
| 260 kHz Fixed-Frequency PWM | Allows predictable EMI filtering and consistent inductor sizing - avoids subharmonic oscillation in continuous conduction mode. |
| Built-in Thermal Shutdown | Protects against sustained overload or poor heatsinking by latching off above ~150°C junction - prevents catastrophic failure. |
| ON/OFF Pin with 50 μA Standby | Supports system-level power sequencing and ultra-low-power sleep states - extends battery life in portable applications. |
Applications
| Industrial PLC Power Supply | Embedded System Pre-Regulator |
|---|---|
Use Scenario: Provides clean 3.3V rail for microcontrollers, FPGAs, and I/O peripherals in programmable logic controllers operating from 24V DC industrial bus. IC Role / Device Role / Timing Role: Primary buck converter delivering regulated 3.3V at up to 5A with high line/load regulation and thermal resilience. Use Value: Replaces linear regulators to cut power loss by >70%, enabling fanless enclosure design and meeting EN 61000-6-4 emission limits. | Use Scenario: Generates 3.3V intermediate rail from 12V or 24V board-level supply to feed downstream LDOs and analog circuitry in medical imaging modules. IC Role / Device Role / Timing Role: High-efficiency pre-regulator minimizing heat buildup near sensitive analog sections and timing circuits. Use Value: Achieves 82% efficiency at full load, reducing thermal gradient across PCB and improving ADC reference stability. |
| Telecom Line Card Power | Test Equipment Power Module |
Use Scenario: Powers FPGA-based signal processing units on telecom line cards drawing bursty 3.3V loads up to 4.5A from 48V backplane. IC Role / Device Role / Timing Role: Step-down regulator with fast transient response and built-in current limiting to survive hot-swap events. Use Value: Delivers <100 mV output deviation during 1A–4.5A load steps (100 μs recovery), ensuring deterministic FPGA operation. | Use Scenario: Supplies 3.3V to digital control logic and interface ICs in automated test equipment requiring high reliability and long-term calibration stability. IC Role / Device Role / Timing Role: Primary DC/DC converter with ±2% output accuracy and −40°C to +125°C operation for extended environmental testing. Use Value: Maintains output tolerance without recalibration across temperature cycles, reducing maintenance downtime and NIST traceability overhead. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2678T-3.3 | TO-220-7 package; higher θJA (45–65°C/W); no exposed DAP; through-hole mounting. | Suitable for prototyping or low-volume assemblies where thermal vias are impractical and airflow is available. | Select when manual assembly, heatsink attachment, or legacy footprint compatibility is required - not drop-in with LM2678SD-3.3. |
| LM2596T-3.3 | 3A rated; 150 kHz switching; higher RDS(ON) (~0.16Ω); wider input (4.5–40V); adjustable versions only. | Lower cost for ≤3A loads; less efficient at 5A; requires external feedback resistors even for 3.3V output. | Choose for cost-sensitive, lower-current applications where 5A headroom and VSON footprint are unnecessary. |
Compared with LM2678T-3.3 and LM2596T-3.3, the LM2678SD-3.3 offers superior thermal performance in surface-mount layouts, guaranteed 5A capability, and true fixed-output simplicity - making it optimal for high-density, production-ready 3.3V power rails.
Availability
LM2678SD-3.3 is available at Aetrix Electronics and suitable for industrial automation, embedded computing, and test equipment applications requiring stable component supply, long-lifecycle support, and RoHS-compliant packaging.
Supply support for LM2678SD-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
Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and power management ICs, with decades of expertise in high-reliability power conversion solutions.
The LM2678 series belongs to TI's SIMPLE SWITCHER® family - designed specifically for rapid, robust DC/DC buck regulator implementation using minimal external components and industry-standard magnetics.
FAQ
What is the maximum continuous output current of the LM2678SD-3.3?
The LM2678SD-3.3 is rated for continuous 5A output current under proper thermal conditions - verified across −40°C to +125°C junction temperature with adequate PCB copper and thermal vias. Its current limit is typically 7A, providing margin for transient surges. Derating applies above 85°C ambient; full 5A is achievable with θJA ≤29°C/W layout.
Does the LM2678SD-3.3 require external feedback resistors to set the 3.3V output?
No, the LM2678SD-3.3 does not require external feedback resistors. It integrates precision internal resistors to fix the output at 3.3V with ±2% tolerance over full line, load, and temperature - eliminating trimming, layout sensitivity, and resistor drift concerns. The FB pin (Pin 6) is internally connected and must be left unconnected externally.
What package type is used for the LM2678SD-3.3, and how should the exposed pad be handled?
The LM2678SD-3.3 uses a 14-lead VSON package (NHM0014A) with an exposed die attach pad (DAP). This pad must be soldered to a solid PCB ground plane using ≥12 thermal vias (0.3 mm diameter) to achieve the specified θJA = 29°C/W. Leaving the DAP unconnected degrades thermal performance and risks thermal shutdown under load.
Can the LM2678SD-3.3 operate from a 48V input source?
No, the LM2678SD-3.3 has an absolute maximum input voltage rating of 45V and recommended operating range of 8V–40V. Applying 48V exceeds the Absolute Maximum Rating and may cause immediate or latent damage. For 48V input, consider upstream pre-regulation or alternative converters such as the LM5118 or TPS546D24 with higher VIN ratings.
How does the ON/OFF pin function on the LM2678SD-3.3, and what is its threshold voltage?
The ON/OFF pin (Pin 5) enables or disables the LM2678SD-3.3. It asserts shutdown when pulled below 0.8V (max), drawing only 50 μA quiescent current. Enable occurs above 2.0V (min), with internal 20 μA pull-up. The threshold is 1.4V typical; driving it with standard 3.3V or 5V logic is safe, but voltages >6V violate the absolute maximum rating and must be avoided.
LM2678SD-3.3 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- SIMPLE SWITCHER®
- Package/Case:
- 14-VDFN Exposed Pad
- 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):
- 8V
- Voltage - Input (Max):
- 40V
- Voltage - Output (Min/Fixed):
- 3.3V
- Voltage - Output (Max):
- -
- Current - Output:
- 5A
- Frequency - Switching:
- 260kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 14-VSON (5x6)
LM2678SD-3.3 FAQ
1.How can I place an order for LM2678SD-3.3 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2678SD-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 LM2678SD-3.3 reliable?
The price and inventory of LM2678SD-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 LM2678SD-3.3 is usually 5 days.
3.What payment methods are accepted for LM2678SD-3.3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2678SD-3.3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2678SD-3.3?
LM2678SD-3.3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2678SD-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 LM2678SD-3.3?
For technical support, including LM2678SD-3.3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2678SD-3.3 requirements.
6.How does Aetrix verify that LM2678SD-3.3 is sourced from the original manufacturer or authorized distributors?
All LM2678SD-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 LM2678SD-3.3 meets industry standards.
7.What is the process for return or replacement of LM2678SD-3.3?
All LM2678SD-3.3 units undergo pre-shipment inspection (PSI). If there is an issue with LM2678SD-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 LM2678SD-3.3 part is unused and in its original packaging.
Return procedure for LM2678SD-3.3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM2678SD-3.3 Tags
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