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Texas Instruments LM2678SDX-12
- Part No.:
- LM2678SDX-12
- Manufacturer:
- Texas Instruments
- Package:
- 14-VDFN Exposed Pad
- Datasheet:
-
LM2678SDX-12.pdf
- Description:
- IC REG BUCK 12V 5A 14VSON
- Quantity:
- Payment:
- Shipping:
Inventory:4,186
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Product details
Overview
LM2678SDX-12 from Texas Instruments is a monolithic 5A step-down (buck) DC/DC voltage regulator with fixed 12V output, 260 kHz internal oscillator, 120 mΩ DMOS power switch, and wide 8V–40V input range. It delivers high efficiency up to 92% at 24VIN/5A, supports −40°C to +125°C junction operation, and integrates thermal shutdown, current limiting, and ON/OFF control for industrial power supply pre-regulation.
For engineers reviewing the LM2678SDX-12 datasheet, LM2678SDX-12 pinout, LM2678SDX-12 application, or LM2678SDX-12 equivalent, key selection criteria include its fixed 12V output tolerance (±2%), standby current (50 μA), thermal resistance (θJA = 29°C/W with vias), and compatibility with standard off-the-shelf inductors and Schottky catch diodes in compact VSON-14 layouts.
Technical Context
The LM2678SDX-12 implements a fixed-frequency PWM buck controller with internal 260 kHz oscillator and cycle-by-cycle current limiting. Its DMOS power switch features 120 mΩ RDS(ON) and supports continuous 5A load current with duty cycle up to 91%.
Feedback is internally trimmed for 12V output-no external resistors required-and regulation maintains ±2% accuracy over full line (15V–40VIN) and load (100mA–5A) conditions. Thermal shutdown activates at TJ ≥ 165°C, and ON/OFF control enables low-quiescent 50 μA standby mode.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 12V ±2% over 15V–40V input and 100mA–5A load - ensures stable rail for downstream logic or analog circuitry without trimming. |
| Efficiency | Up to 92% at VIN = 24V, IOUT = 5A - reduces thermal load and improves system power density in space-constrained designs. |
| Switch RDS(ON) | 120 mΩ typical - minimizes conduction loss and enables 5A continuous output without external MOSFETs. |
| Oscillator Frequency | 260 kHz ±11% - enables use of physically small, industry-standard inductors (e.g., 10–22 μH) and simplifies EMI filtering. |
| Standby Current | 50 μA max when ON/OFF pin = 0V - supports low-power sleep modes in battery-backed or energy-conscious systems. |
| Thermal Resistance | θJA = 29°C/W with 12 vias to second-layer copper - enables reliable 5A operation on standard 4-layer PCBs without heatsinks. |
| Input Voltage Range | 8V to 40V - accommodates unregulated 12V/24V/36V industrial bus rails and automotive cold-crank transients. |
Pinout & Package
VSON-14 package (NHM0014A) with exposed die attach pad (DAP) for thermal enhancement; DAP must be connected to PCB ground plane via ≥12 thermal vias for rated 5A performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Input Power Supply | Accepts 8V–40V unregulated input; requires local 100 μF+ low-ESR capacitor for stability and transient response. |
| VSW | Switch Node | Drives external catch diode and inductor; swings from VIN to ~−0.5V during OFF time - requires tight layout to minimize ringing. |
| GND | Power Ground | Primary return path for high-current switch loop; must connect directly to DAP and input/output capacitors. |
| ON/OFF | Enable Control Input | Logic-level shutdown: <0.8V disables regulator (50 μA IQ); >2.0V enables; internal 20 μA pull-up allows open-circuit default ON. |
| FB | Feedback Reference | Internally connected to 12V divider - no external components needed; not used in fixed-output configuration. |
| DAP | Thermal Pad | Electrically tied to GND; mandatory connection to PCB ground plane with ≥12 vias for θJA = 29°C/W rating. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 120 mΩ DMOS Switch | Eliminates need for external high-side MOSFET and gate driver, reducing BOM count and layout complexity. |
| 260 kHz Fixed-Frequency Operation | Enables predictable EMI spectrum and consistent inductor sizing across design variants without frequency tuning. |
| ±2% Output Voltage Accuracy | Meets tight regulation requirements for FPGA core supplies, industrial sensors, and analog front-ends without post-regulation. |
| 50 μA Standby Quiescent Current | Supports always-on subsystems (e.g., real-time clocks, CAN wake-up receivers) while minimizing battery drain. |
| Built-in Thermal Shutdown & Current Limit | Provides autonomous fault protection without external monitoring circuitry - resets automatically after cooling or load removal. |
Applications
| Industrial PLC Power Rails | Automotive Body Control Modules |
|---|---|
Use Scenario: Providing clean, regulated 12V for microcontroller, CAN transceiver, and sensor interface circuits in programmable logic controllers. IC Role / Device Role / Timing Role: Primary step-down regulator converting 24V industrial bus to stable 12V system rail. Use Value: Delivers 5A continuous current with 92% efficiency and ±2% tolerance - eliminates need for secondary linear regulators and reduces board heat. | Use Scenario: Generating 12V supply for body electronics (door modules, lighting controllers) from vehicle battery (9V–16V nominal, up to 40V during load dump). IC Role / Device Role / Timing Role: High-reliability buck converter handling wide-input automotive transients and meeting AEC-Q100 temperature requirements. Use Value: Operates from −40°C to +125°C junction, withstands 40V input surges, and provides 50 μA shutdown for low-static-current compliance. |
| Telecom Line Card Pre-regulators | Test Equipment Power Supplies |
Use Scenario: Converting −48V telecom rectified bus (via intermediate +12V stage) to isolated 12V for digital signal processors and FPGAs. IC Role / Device Role / Timing Role: Efficient pre-regulator enabling compact, fanless line card designs with minimal thermal footprint. Use Value: 260 kHz switching allows small magnetics; 120 mΩ RDS(ON) sustains 5A output without derating at elevated ambient temperatures. | Use Scenario: Building benchtop or modular test equipment power supplies requiring stable, adjustable 12V outputs with fast transient response. IC Role / Device Role / Timing Role: Core switching regulator in programmable DC source modules where reliability and repeatable performance are critical. Use Value: Internal current limit and thermal shutdown ensure robust operation under short-circuit and overload testing conditions. |
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-12/NOPB | TO-220-7 package; higher θJA (65°C/W, no heatsink); same electrical specs and pinout except physical form factor. | Requires heatsink for 5A continuous operation; suited for prototyping or low-volume through-hole assembly. | Select when mechanical mounting or legacy TO-220 footprint is required; verify thermal margin with heatsink. |
| LM2596T-12 | 3A rated; 150 kHz oscillator; 370 mΩ RDS(ON); wider 4.5V–40V input but lower current capability. | Not suitable for 5A loads; acceptable for ≤3A 12V rails where cost or size constraints favor smaller inductors. | Choose only if load current remains ≤3A; expect ~5–8% lower efficiency at full load vs. LM2678SDX-12. |
Compared with LM2678T-12/NOPB, the LM2678SDX-12 offers superior thermal performance in surface-mount form, while LM2596T-12 trades current capacity and efficiency for lower cost and smaller passive components - making it viable only for sub-3A applications where 12V regulation stability and thermal headroom are less critical.
Availability
LM2678SDX-12 is available at Aetrix Electronics and suitable for industrial PLC power rails, automotive body control modules, and telecom line card pre-regulators requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for LM2678SDX-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
Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and power management ICs, with decades of expertise in high-efficiency DC/DC conversion.
The LM2678 series belongs to TI's SIMPLE SWITCHER® family - designed specifically for engineers needing robust, easy-to-implement buck regulators with minimal external components and proven reliability in harsh environments.
FAQ
What is the maximum continuous output current of the LM2678SDX-12?
The LM2678SDX-12 is rated for 5A continuous output current under proper thermal conditions: PCB layout with DAP connected to ground plane via ≥12 vias, ambient temperature ≤60°C, and adequate copper area. At 5A, efficiency reaches 92% with 24V input, and thermal shutdown activates only above 165°C junction temperature.
Does the LM2678SDX-12 require external feedback resistors to set the output voltage?
No - the LM2678SDX-12 is a fixed-output variant with internal resistor divider trimmed to deliver 12V ±2%. The FB pin is internally connected and must not be externally biased; adding external components will disrupt regulation and may cause instability or overvoltage.
Can the LM2678SDX-12 operate from a 12V input to produce 12V output?
No - the LM2678SDX-12 requires minimum 15V input for 12V output operation per datasheet specifications. At VIN < 15V, regulation fails due to insufficient duty cycle margin; the device cannot achieve 100% duty cycle, and output drops below 12V. Use only within 15V–40V input range.
What is the purpose of the BOOST capacitor in the LM2678SDX-12 circuit?
The BOOST capacitor (0.01 μF ceramic, rated ≥50V) connects between VSW and the BOOST pin (Pin 3) to generate a gate-drive voltage above VIN, fully enhancing the internal DMOS switch. This reduces RDS(ON) and conduction losses - critical for maintaining 92% efficiency at 5A. Omitting it causes severe efficiency drop and thermal stress.
Is the LM2678SDX-12 RoHS-compliant and halogen-free?
Yes - the LM2678SDX-12 is manufactured in accordance with TI's Green Standard, meeting RoHS Directive 2011/65/EU and JEDEC JS709C halogen-free requirements. The VSON-14 package uses matte tin lead finish and lead-free solderable terminations, verified per TI's published material declarations.
LM2678SDX-12 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):
- 15V
- Voltage - Input (Max):
- 40V
- Voltage - Output (Min/Fixed):
- 12V
- 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)
LM2678SDX-12 FAQ
1.How can I place an order for LM2678SDX-12 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2678SDX-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 LM2678SDX-12 reliable?
The price and inventory of LM2678SDX-12 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2678SDX-12 is usually 5 days.
3.What payment methods are accepted for LM2678SDX-12?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2678SDX-12 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2678SDX-12?
LM2678SDX-12 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2678SDX-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 LM2678SDX-12?
For technical support, including LM2678SDX-12 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2678SDX-12 requirements.
6.How does Aetrix verify that LM2678SDX-12 is sourced from the original manufacturer or authorized distributors?
All LM2678SDX-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 LM2678SDX-12 meets industry standards.
7.What is the process for return or replacement of LM2678SDX-12?
All LM2678SDX-12 units undergo pre-shipment inspection (PSI). If there is an issue with LM2678SDX-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 LM2678SDX-12 part is unused and in its original packaging.
Return procedure for LM2678SDX-12:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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