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Texas Instruments LM2678SD-ADJ
- Part No.:
- LM2678SD-ADJ
- Manufacturer:
- Texas Instruments
- Package:
- 14-VDFN Exposed Pad
- Datasheet:
-
LM2678SD-ADJ.pdf
- Description:
- IC REG BUCK ADJ 5A 14VSON
- Quantity:
- Payment:
- Shipping:
Inventory:3,894
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Product details
Overview
LM2678SD-ADJ from Texas Instruments is a monolithic step-down (buck) DC/DC switching regulator IC delivering up to 5A output current with adjustable output voltage (1.2V to 37V), 260kHz fixed-frequency operation, and 8V–40V input range. It integrates a 120mΩ DMOS high-side switch and supports efficient system preregulation in industrial power supplies.
For engineers reviewing the LM2678SD-ADJ datasheet, LM2678SD-ADJ pinout, LM2678SD-ADJ application, or LM2678SD-ADJ equivalent, key selection criteria include its ±2% output tolerance over line/load/temperature, 50μA standby current in shutdown mode, thermal shutdown and current limiting protection, and compatibility with standard off-the-shelf inductors for rapid design implementation.
Technical Context
The LM2678SD-ADJ implements a fixed-frequency PWM controller with internal 260kHz oscillator and voltage-mode feedback architecture. Its high-side DMOS switch operates with 0.12Ω typical RDS(ON) at 25°C, enabling >90% efficiency at full load under optimized conditions. The FB pin senses output voltage via external resistor divider to regulate adjustable output precisely.
Functional modes include active regulation (ON/OFF ≥1.4V) and low-quiescent shutdown (ON/OFF ≤0.8V), with built-in thermal shutdown, cycle-by-cycle current limiting (6.1–8.3A), and 50–150μA standby current across –40°C to 125°C junction temperature range.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | Up to 5A continuous load capability with integrated 120mΩ DMOS switch |
| Input Voltage Range | 8V to 40V - supports wide-range industrial and battery-derived inputs |
| Output Voltage Range | Adjustable 1.2V to 37V - set via external resistor divider on FB pin |
| Switching Frequency | 260kHz fixed - enables use of compact magnetics and predictable EMI profile |
| Feedback Voltage | 1.21V ±1.2% - defines output accuracy: VOUT = 1.21V × (1 + R1/R2) |
| Efficiency | Up to 92% - achieved at 12V input / 5V output / 5A load with optimized layout |
| Standby Current | 50μA typical - enables ultra-low-power shutdown in battery-backed systems |
| Thermal Range | –40°C to 125°C TJ - rated for harsh industrial and automotive under-hood environments |
Pinout & Package
LM2678SD-ADJ is packaged in the 7-pin KTW (TO-263) surface-mount package with exposed thermal pad (DAP) connected to GND. Pin 1 is Switch_output, Pin 2 is Input, Pin 3 is CB (bootstrap capacitor connection), Pin 4 is GND, Pin 5 is NC, Pin 6 is FB (feedback sense), and Pin 7 is ON/OFF (enable control).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (SW) | Switch output | Drain node of internal high-side DMOS FET; connects to inductor and cathode of external Schottky diode |
| 2 (VIN) | Input supply | Primary power input (8–40V); must be bypassed with low-ESR capacitor placed adjacent to pin |
| 3 (CB) | Bootstrap capacitor | Connects 100nF ceramic capacitor to SW pin to drive gate above VIN for full FET enhancement |
| 4 (GND) | Power ground | Main return path for input/output capacitors and thermal pad; requires low-inductance PCB copper pour |
| 5 (NC) | No connect | Internally unconnected; must remain floating or tied to GND per layout best practice |
| 6 (FB) | Feedback sense | High-impedance input (85nA bias) monitoring output voltage divider; sensitive to noise coupling |
| 7 (ON/OFF) | Enable control | Logic-level input: ≥1.4V = active regulation, ≤0.8V = shutdown (50μA IQ) |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 120mΩ DMOS switch | Reduces conduction loss and eliminates need for external high-current MOSFET driver |
| 260kHz fixed-frequency oscillator | Enables consistent EMI filtering design and use of standardized, low-profile inductors |
| ±2% output voltage tolerance | Guarantees tight regulation across full line, load, and temperature without trimming |
| 50μA shutdown quiescent current | Extends battery life in portable or always-on standby applications |
| Built-in protection suite | Includes thermal shutdown, cycle-by-cycle current limiting, and safe startup sequencing |
| WEBENCH® Power Designer support | Provides validated bill-of-materials, schematic, and performance simulation for LM2678SD-ADJ designs |
Applications
| Industrial Power Supply | Battery Charger |
|---|---|
Use Scenario: Converting 24V rail to 5V/3.3V for PLC I/O modules and sensor interfaces in factory automation. IC Role / Device Role / Timing Role: Primary buck regulator providing stable, high-current DC output with thermal robustness for continuous operation. Use Value: Delivers 5A at >90% efficiency with integrated switch and protection-reducing BOM count and board space vs discrete solutions. | Use Scenario: Preregulating 36V battery pack voltage down to 12V before linear charging stage in EV auxiliary systems. IC Role / Device Role / Timing Role: High-efficiency step-down converter operating in continuous conduction mode with precise voltage setting. Use Value: Adjustable output (1.2–37V) and 8–40V input range enable flexible charge-voltage tailoring; 260kHz frequency simplifies filter design. |
| Test Equipment Power | Medical Diagnostic Module |
Use Scenario: Generating clean, low-noise 15V supply for analog front-end circuitry in portable multimeters and oscilloscopes. IC Role / Device Role / Timing Role: Efficient preregulator feeding low-dropout linear regulators to minimize ripple and noise. Use Value: 50μA shutdown current preserves battery during idle; ±2% output tolerance ensures measurement accuracy stability. | Use Scenario: Providing isolated 3.3V logic supply and 12V analog bias for ultrasound transducer drivers in handheld diagnostic devices. IC Role / Device Role / Timing Role: Compact, thermally reliable DC/DC converter meeting stringent safety and reliability requirements. Use Value: TO-263 (KTW) package with exposed DAP enables effective heat dissipation in sealed enclosures; –40°C to 125°C rating supports clinical environment operation. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2596-ADJ | 3A output current, 150kHz switching frequency, higher RDS(ON) (0.22Ω), no integrated thermal pad | Limited to lower-power applications; less suitable for sustained 5A loads or high-ambient-temperature environments | Select LM2678SD-ADJ when 5A output, 260kHz EMI control, or enhanced thermal performance is required. |
| TPS54560B | 5A output, 100V max input, 2.5–60V input range, adjustable frequency (100kHz–2.5MHz), smaller 8-pin SOIC package | Higher input voltage capability and programmable frequency; lacks integrated thermal pad and fixed 260kHz simplicity | Choose LM2678SD-ADJ for cost-sensitive, fixed-frequency, high-reliability industrial designs where 40V max input suffices. |
Compared with LM2596-ADJ and TPS54560B, the LM2678SD-ADJ offers superior thermal management via its TO-263 package, deterministic 260kHz operation for repeatable EMI filtering, and tighter ±2% output tolerance-making it optimal for high-current, thermally constrained, or precision-regulated industrial power rails.
Availability
LM2678SD-ADJ is available at Aetrix Electronics and suitable for industrial power supplies, battery chargers, and test equipment requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LM2678SD-ADJ 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 technologies with over 90 years of innovation history.
The LM2678 series belongs to TI's SIMPLE SWITCHER® power converter family, designed specifically for rapid, reliable, and low-component-count DC/DC buck regulator implementations in industrial, automotive, and medical power systems.
FAQ
What is the maximum output current supported by the LM2678SD-ADJ?
The LM2678SD-ADJ delivers up to 5A continuous output current when used with appropriate external components, adequate PCB copper area, and within its thermal limits. This rating assumes proper heatsinking via the exposed DAP pad in the KTW package and operation within the recommended input voltage (8V–40V) and junction temperature (–40°C to 125°C) ranges. Derating applies at elevated ambient temperatures or reduced airflow.
How do I set the output voltage for the LM2678SD-ADJ?
The LM2678SD-ADJ output voltage is set using an external resistor divider connected between VOUT, FB, and GND. With a nominal feedback voltage of 1.21V, VOUT = 1.21V × (1 + R1/R2). For example, to achieve 5V output, use R1 = 3.16kΩ and R2 = 1.0kΩ. The FB pin draws only 85nA bias current, minimizing divider power loss and ensuring high accuracy across temperature.
Does the LM2678SD-ADJ require an external bootstrap capacitor?
Yes, the LM2678SD-ADJ requires a 100nF ceramic capacitor connected between the CB pin and the SW pin to provide gate-drive voltage above VIN for the internal high-side DMOS switch. This bootstrap configuration ensures full enhancement of the 120mΩ switch, maintaining high efficiency. Placement must be low-inductance and adjacent to pins 1 and 3 to prevent ringing or gate-drive instability.
What protection features are built into the LM2678SD-ADJ?
The LM2678SD-ADJ integrates thermal shutdown, cycle-by-cycle current limiting (6.1–8.3A), and undervoltage lockout. It also supports controlled shutdown via the ON/OFF pin, reducing quiescent current to 50μA. These protections operate autonomously without external circuitry, safeguarding both the IC and downstream loads during overload, short-circuit, or overtemperature events-critical for unattended industrial operation.
Can the LM2678SD-ADJ be synchronized to an external clock?
No, the LM2678SD-ADJ uses an internal fixed-frequency 260kHz oscillator and does not support external clock synchronization. Its timing is fully self-contained to simplify design and ensure stable operation without external timing components. For applications requiring frequency coordination or EMI spreading, alternative regulators such as the TPS54560B should be considered.
LM2678SD-ADJ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- SIMPLE SWITCHER®
- Package/Case:
- 14-VDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Not For New Designs
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 8V
- Voltage - Input (Max):
- 40V
- Voltage - Output (Min/Fixed):
- 1.21V
- Voltage - Output (Max):
- 37V
- 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-ADJ FAQ
1.How can I place an order for LM2678SD-ADJ through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2678SD-ADJ 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-ADJ reliable?
The price and inventory of LM2678SD-ADJ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2678SD-ADJ is usually 5 days.
3.What payment methods are accepted for LM2678SD-ADJ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2678SD-ADJ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2678SD-ADJ?
LM2678SD-ADJ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2678SD-ADJ 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-ADJ?
For technical support, including LM2678SD-ADJ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2678SD-ADJ requirements.
6.How does Aetrix verify that LM2678SD-ADJ is sourced from the original manufacturer or authorized distributors?
All LM2678SD-ADJ 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-ADJ meets industry standards.
7.What is the process for return or replacement of LM2678SD-ADJ?
All LM2678SD-ADJ units undergo pre-shipment inspection (PSI). If there is an issue with LM2678SD-ADJ, 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-ADJ part is unused and in its original packaging.
Return procedure for LM2678SD-ADJ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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