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Texas Instruments LM2678SDX-5.0/NOPB
- Part No.:
- LM2678SDX-5.0/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- 14-VDFN Exposed Pad
- Datasheet:
-
LM2678SDX-5.0/NOPB.pdf
- Description:
- IC REG BUCK 5V 5A 14VSON
- Quantity:
- Payment:
- Shipping:
Inventory:4,274
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Product details
Overview
LM2678SDX-5.0/NOPB from Texas Instruments is a monolithic 5A step-down (buck) DC/DC switching regulator with fixed 5V output, 8–40V input range, 260kHz fixed-frequency oscillator, ±2% output voltage tolerance, and integrated 120mΩ DMOS high-side switch - used in industrial power supplies and battery-based systems requiring high-efficiency regulation.
For engineers reviewing the LM2678SDX-5.0/NOPB datasheet, LM2678SDX-5.0/NOPB pinout, LM2678SDX-5.0/NOPB application, or LM2678SDX-5.0/NOPB equivalent, key selection criteria include thermal performance in TO-263-7 package, ON/OFF control interface, feedback configuration for fixed-output operation, and compatibility with standard off-the-shelf inductors and Schottky diodes.
Technical Context
The LM2678SDX-5.0/NOPB implements a voltage-mode PWM controller with internal 260kHz oscillator and integrated high-side DMOS FET. Its fixed 5V output version eliminates external feedback resistors, using internal precision divider referenced to 1.21V feedback threshold.
It operates in continuous conduction mode up to 5A load, supports shutdown via logic-level ON/OFF pin (1.4V threshold), and delivers 84% typical efficiency at 12VIN/5VOUT/5A - enabled by low RDS(ON) (0.12Ω @ 25°C) and optimized gate drive with bootstrap capacitor (CB) circuitry.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 5.0V ±2% over full line/load/temperature (–40°C to 125°C), eliminating external resistor network. |
| Input Voltage Range | 8V to 40V DC - supports wide-range industrial and automotive battery inputs without pre-regulation. |
| Max Output Current | 5A continuous - enables single-chip conversion for mid-power subsystems (e.g., FPGA core rails, motor drivers). |
| Switching Frequency | 260kHz fixed - allows use of compact, standardized inductors (e.g., 10µH) and reduces EMI compared to lower frequencies. |
| RDS(ON) | 0.12Ω typical @ 25°C - minimizes conduction loss and thermal rise under full load, supporting TO-263 thermal design. |
| Standby Current | 50µA max when ON/OFF pin = 0V - enables ultra-low-power sleep modes in portable and energy-conscious systems. |
| Efficiency | 84% typical @ 12VIN, 5VOUT, 5A - achieved via low-loss DMOS switch and optimized control architecture. |
Pinout & Package
LM2678SDX-5.0/NOPB is packaged in KTW (TO-263-7), a thermally enhanced surface-mount variant of TO-220 with exposed DAP for PCB heat sinking. The 7-pin layout supports high-current routing and simplified thermal management in dense layouts.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (SW) | Switch output | Drain node of internal high-side DMOS FET - connects directly to inductor and cathode of external Schottky diode; switches between VIN and ~–0.5V. |
| 2 (VIN) | Input supply | Main power input (8–40V); requires low-ESR bypass capacitor placed adjacent to pin to suppress high-frequency transients. |
| 3 (CB) | Bootstrap capacitor | Connects to SW pin via 100nF ceramic capacitor - generates gate drive voltage > VIN to fully enhance internal FET and minimize RDS(ON). |
| 4 (GND) | Power ground | Primary return path for input/output capacitors and internal circuitry; must be tied to large copper area for thermal and noise control. |
| 5 (NC) | No connect | Internally unconnected - must remain floating; no routing or soldering required. |
| 6 (FB) | Feedback sense | Internally connected to 5V output divider - for fixed 5V version, connect directly to VOUT; no external resistors needed. |
| 7 (ON/OFF) | Enable control | Logic-compatible shutdown input - <0.8V disables regulator (50µA ISTBY); >1.4V enables operation; internal 20µA pull-up. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 120mΩ DMOS switch | Enables 5A output without external MOSFETs - reduces BOM count and layout complexity while maintaining >84% efficiency. |
| Fixed 5V output with internal feedback | Eliminates external resistor network and associated tolerance drift - ensures ±2% regulation across temperature and load. |
| 260kHz fixed-frequency PWM | Allows predictable EMI filtering and use of standardized, low-cost inductors - avoids frequency jitter and simplifies compliance testing. |
| ON/OFF pin with 50µA standby | Supports system-level power sequencing and low-power sleep states - compatible with microcontroller GPIO without level-shifting. |
| Thermal shutdown & current limiting | Protects against overload and ambient overheating - latches off until reset via ON/OFF pin toggle or VIN cycle. |
Applications
| Industrial Power Supply | Battery-Based Equipment |
|---|---|
|
Use Scenario: 24V rail conversion to 5V for PLC I/O modules and sensor interfaces operating in harsh environments. IC Role / Device Role / Timing Role: Primary buck regulator delivering regulated 5V at up to 5A with high line/load regulation and thermal robustness. Use Value: Enables single-stage conversion from 24V industrial bus without linear preregulator losses - maintains >82% efficiency across –40°C to 85°C ambient. |
Use Scenario: Portable test equipment powered by 12–36V Li-ion packs requiring stable 5V for MCU, display, and USB peripherals. IC Role / Device Role / Timing Role: Main DC/DC converter with enable control synchronized to system sleep/wake cycles. Use Value: 50µA shutdown current extends battery runtime during idle; wide 8–40V input accommodates pack voltage sag and charging transients. |
| Embedded System Preregulator | LED Driver Power Stage |
|
Use Scenario: Pre-regulating 24V input to 5V before LDOs powering sensitive analog and RF circuits in communication gateways. IC Role / Device Role / Timing Role: High-efficiency intermediate stage reducing thermal load on downstream LDOs. Use Value: Delivers clean 5V with <1% ripple (with proper COUT) and ±2% accuracy - lowers LDO dropout requirements and improves PSRR. |
Use Scenario: Constant-voltage power stage for multi-string LED arrays in signage or architectural lighting with 12–36V input. IC Role / Device Role / Timing Role: Buck converter supplying stable 5V to LED driver ICs or microcontroller-based dimming controllers. Use Value: Robust 5A capability supports auxiliary circuitry alongside LED strings; ON/OFF pin enables synchronized dimming or fault shutdown. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2675MX-5.0/NOPB | 3A output rating, same 5V fixed output, identical pinout but smaller SOIC-8 package; lacks thermal pad and higher current capability. | Suitable for lower-power designs (<3A) where board space is constrained and thermal dissipation is less demanding. | Select when 3A suffices and TO-263 footprint is undesirable; verify thermal margin with reduced copper area. |
| TPS54560BDDAR | 5.5A output, adjustable output (0.8–60V), 100kHz–2.5MHz programmable frequency, integrated soft-start; different pinout and control scheme. | Preferred for designs requiring output flexibility, higher switching frequencies, or tighter transient response than fixed 260kHz allows. | Choose when adjustable VOUT, wider frequency range, or enhanced protection features (e.g., UVLO hysteresis) are required. |
Compared with LM2678SDX-5.0/NOPB, LM2675MX-5.0/NOPB offers footprint reduction at the cost of current and thermal headroom, while TPS54560BDDAR provides design flexibility and modern feature set at the expense of increased external component count and layout complexity.
Availability
LM2678SDX-5.0/NOPB is available at Aetrix Electronics and suitable for industrial power supplies, battery-powered instrumentation, embedded preregulators, and LED driver subsystems requiring stable component supply and long-term manufacturability.
Supply support for LM2678SDX-5.0/NOPB 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 decades of expertise in high-reliability power conversion ICs.
The LM2678 series belongs to TI's SIMPLE SWITCHER® family - designed specifically for ease-of-use in non-isolated DC/DC buck applications, minimizing external component count while delivering robust 5A performance in industrial and commercial systems.
FAQ
What is the maximum input voltage rating for LM2678SDX-5.0/NOPB?
The absolute maximum input voltage for LM2678SDX-5.0/NOPB is 45V, but the recommended operating range is 8V to 40V DC. Exceeding 40V continuously may impact reliability and thermal performance, especially under high load conditions. The device includes internal protection against overvoltage stress on the VIN pin, but sustained operation above 40V is outside specification and not guaranteed.
Does LM2678SDX-5.0/NOPB require external feedback resistors for 5V output?
No, LM2678SDX-5.0/NOPB does not require external feedback resistors. It is the fixed 5V output variant with internal resistor divider connected to the FB pin, enabling direct connection to the output capacitor. This eliminates resistor tolerance errors and simplifies layout - unlike the adjustable version (LM2678-ADJ), which requires two external resistors to set VOUT.
How is thermal performance managed in the KTW (TO-263-7) package of LM2678SDX-5.0/NOPB?
LM2678SDX-5.0/NOPB in KTW package uses an exposed die attach paddle (DAP) electrically and thermally connected to GND. For optimal thermal performance, the DAP must be soldered to a minimum 0.4896 in² (3.6× package area) copper plane with ≥12 thermal vias to inner ground layers. With this layout, RθJA drops to 35°C/W, enabling full 5A operation at up to 85°C ambient without forced airflow.
Can LM2678SDX-5.0/NOPB be synchronized to an external clock?
No, LM2678SDX-5.0/NOPB cannot be synchronized to an external clock. It uses an internal fixed-frequency 260kHz oscillator with ±11% tolerance. There is no SYNC pin or frequency adjustment capability - unlike newer regulators such as TPS54560B, which support external synchronization for EMI reduction or multi-rail phase alignment.
What is the purpose of the CB pin on LM2678SDX-5.0/NOPB, and what capacitor value is recommended?
The CB (bootstrap capacitor) pin on LM2678SDX-5.0/NOPB provides gate drive voltage for the internal high-side DMOS switch. A 100nF (0.01µF) X7R ceramic capacitor must be placed between CB and SW pins to ensure full enhancement of the FET and maintain low RDS(ON). This capacitor recharges on each switching cycle via an internal diode; incorrect value or poor placement causes erratic operation or thermal runaway.
LM2678SDX-5.0/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- SIMPLE SWITCHER®
- Package/Case:
- 14-VDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- 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):
- 5V
- 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-5.0/NOPB FAQ
1.How can I place an order for LM2678SDX-5.0/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2678SDX-5.0/NOPB 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-5.0/NOPB reliable?
The price and inventory of LM2678SDX-5.0/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2678SDX-5.0/NOPB is usually 5 days.
3.What payment methods are accepted for LM2678SDX-5.0/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2678SDX-5.0/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2678SDX-5.0/NOPB?
LM2678SDX-5.0/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2678SDX-5.0/NOPB 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-5.0/NOPB?
For technical support, including LM2678SDX-5.0/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2678SDX-5.0/NOPB requirements.
6.How does Aetrix verify that LM2678SDX-5.0/NOPB is sourced from the original manufacturer or authorized distributors?
All LM2678SDX-5.0/NOPB 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-5.0/NOPB meets industry standards.
7.What is the process for return or replacement of LM2678SDX-5.0/NOPB?
All LM2678SDX-5.0/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM2678SDX-5.0/NOPB, 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-5.0/NOPB part is unused and in its original packaging.
Return procedure for LM2678SDX-5.0/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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