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Texas Instruments LM2678SDX-3.3/NOPB
- Part No.:
- LM2678SDX-3.3/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- 14-VDFN Exposed Pad
- Datasheet:
-
LM2678SDX-3.3/NOPB.pdf
- Description:
- IC REG BUCK 3.3V 5A 14VSON
- Quantity:
- Payment:
- Shipping:
Inventory:4,253
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Product details
Overview
LM2678SDX-3.3/NOPB from Texas Instruments is a monolithic step-down (buck) DC-DC switching regulator delivering up to 5 A output current with fixed 3.3 V output, 8 V–40 V input range, 260 kHz fixed-frequency operation, and ±2% output voltage tolerance over full line/load/temperature. It integrates a 120 mΩ DMOS high-side switch and supports ON/OFF control for low-power standby mode in industrial power supplies.
For engineers reviewing the LM2678SDX-3.3/NOPB datasheet, LM2678SDX-3.3/NOPB pinout, LM2678SDX-3.3/NOPB application, or LM2678SDX-3.3/NOPB equivalent, key selection criteria include its 3.3 V fixed output accuracy, thermal shutdown protection, 50 µA standby quiescent current, and compatibility with standard off-the-shelf inductors and Schottky diodes in compact PCB layouts.
Technical Context
The LM2678SDX-3.3/NOPB implements a fixed-frequency PWM buck controller with internal 260 kHz oscillator and integrated 120 mΩ DMOS high-side switch. Its feedback loop uses a direct connection from FB pin to output (no external divider), enabling precise 3.3 V regulation within ±2% across –40°C to 125°C junction temperature.
It operates in continuous conduction mode at full load, features built-in current limiting (6.1–8.3 A), thermal shutdown, and an ON/OFF pin with 1.4 V threshold that reduces quiescent current to 50 µA in shutdown-enabling efficient system-level power sequencing in battery-backed or always-on applications.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3 V ±2% (3.234–3.366 V at 25°C; 3.201–3.399 V over –40°C to 125°C) |
| Input Voltage Range | 8 V to 40 V - supports wide industrial and automotive input rails without pre-regulation |
| Max Output Current | 5 A - enables single-chip conversion for mid-power digital subsystems (e.g., FPGA I/O, MCU cores) |
| Switching Frequency | 260 kHz ±11% - enables use of compact, low-cost 10–22 µH inductors and minimizes EMI below AM band |
| RDS(ON) | 0.12 Ω typical at 25°C - limits conduction loss to < 3 W at 5 A, supporting >90% efficiency at 12 VIN |
| Standby Quiescent Current | 50 µA max at 25°C - allows ultra-low-power sleep states in portable or energy-harvested systems |
| Operating Junction Temp | –40°C to 125°C - qualified for under-hood automotive, industrial motor drives, and outdoor telecom equipment |
Pinout & Package
LM2678SDX-3.3/NOPB is packaged in a 7-pin TO-263 (KTW) surface-mount package with exposed thermal pad (DAP), measuring 10.1 mm × 15.24 mm. The DAP must be soldered to a PCB ground plane for thermal and electrical performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (SW) | Switch output | Drain node of internal DMOS FET; connects to inductor and cathode of external Schottky diode - carries high dv/dt switching current |
| 2 (IN) | Input supply | Primary power input (8–40 V); requires low-ESR ceramic bypass capacitor placed within 5 mm for stable high-frequency operation |
| 3 (CB) | Bootstrap capacitor | Connects 100 nF ceramic capacitor to SW pin to generate gate drive voltage > VIN for full enhancement of internal FET |
| 4 (GND) | Power ground | Main return path for input/output currents; must tie directly to thermal pad and low-impedance ground plane to minimize noise and thermal resistance |
| 5 (NC) | No connect | Internally unconnected; must remain floating - no routing or copper fill allowed |
| 6 (FB) | Feedback sense | Direct connection to 3.3 V output (no resistor divider); internal reference sets regulation point - sensitive to noise coupling |
| 7 (ON/OFF) | Enable control | Logic-level input: ≥1.4 V = active regulation; ≤0.8 V = shutdown (50 µA IQ); internal 20 µA pull-up simplifies interface |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 120 mΩ DMOS switch | Eliminates need for external high-side MOSFET and driver, reducing BOM count and layout complexity in 5 A buck designs |
| Fixed 3.3 V output with ±2% tolerance | Meets tight core voltage requirements for modern microcontrollers and FPGAs without external feedback resistors or trimming |
| 260 kHz fixed-frequency oscillator | Enables predictable EMI filtering and consistent inductor sizing across production batches and design revisions |
| Thermal shutdown + current limit | Protects against sustained overload or poor heatsinking - automatically recovers after fault removal without latch-up |
| ON/OFF pin with 50 µA standby | Supports system-level power sequencing and deep-sleep modes in battery-powered or energy-conscious applications |
Applications
| Industrial PLC Power Supply | Automotive Infotainment Core Rail |
|---|---|
Use Scenario: Provides primary 3.3 V rail for programmable logic controllers operating in harsh factory environments with 24 V DC input. IC Role / Device Role / Timing Role: Primary buck regulator delivering regulated 3.3 V to ARM Cortex-M7 MCU, Ethernet PHY, and isolated I/O drivers. Use Value: ±2% output tolerance ensures reliable digital logic operation across –40°C to 85°C ambient; 125°C junction rating enables convection-cooled enclosure design. | Use Scenario: Generates 3.3 V core supply for infotainment head unit SoC from vehicle battery (9–16 V nominal, up to 40 V load dump). IC Role / Device Role / Timing Role: Pre-regulator stepping down battery voltage before LDOs feed processor cores and DDR memory interfaces. Use Value: 8–40 V input range withstands automotive transients; thermal shutdown prevents damage during prolonged high-temp operation in dashboard mounting. |
| Network Equipment Midplane Converter | Medical Imaging Sensor Interface |
Use Scenario: Powers 3.3 V FPGA configuration and transceiver banks on telecom line cards using centralized 48 V backplane supply. IC Role / Device Role / Timing Role: High-current intermediate bus converter feeding multiple downstream point-of-load regulators. Use Value: 5 A capability supports dense FPGA I/O banks; 260 kHz frequency avoids interference with Ethernet PHY clock domains. | Use Scenario: Supplies clean 3.3 V to low-noise analog front-end (AFE) and ADCs in portable ultrasound probe modules. IC Role / Device Role / Timing Role: Main DC-DC stage preceding low-noise LDOs; operates in forced continuous conduction mode for ripple stability. Use Value: Fixed 3.3 V output eliminates resistor-divider error sources; 50 µA shutdown current extends battery life during idle scanning intervals. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2675SD-3.3/NOPB | Lower 2.5 A output current; same 260 kHz frequency, 3.3 V fixed output, and TO-263 package | Suitable only for sub-3 A loads; lacks current limit headroom for peak FPGA I/O switching | Select when load current remains ≤2.5 A and board space or cost constraints favor smaller thermal footprint |
| TPS54560DGQR | Adjustable output (0.8–60 V), 60 V max input, 5 A, 100–2500 kHz adjustable frequency, MSOP-10 package | Requires external feedback resistors; higher input voltage range but no fixed 3.3 V option | Choose when input exceeds 40 V or programmable frequency/EMI shaping is required - not drop-in compatible |
Compared with LM2675SD-3.3/NOPB, LM2678SDX-3.3/NOPB delivers 100% higher continuous current and superior thermal margin; versus TPS54560DGQR, it offers simpler 3.3 V fixed-output implementation with no resistor network or frequency tuning needed - ideal for cost-sensitive, high-volume industrial power rails.
Availability
LM2678SDX-3.3/NOPB is available at Aetrix Electronics and suitable for industrial PLC power supplies, automotive infotainment core rails, and network equipment midplane converters requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LM2678SDX-3.3/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 rapid, robust, and low-component-count buck regulator implementations in industrial, automotive, and communications infrastructure applications.
FAQ
What is the maximum input voltage rating for LM2678SDX-3.3/NOPB?
The absolute maximum input voltage for LM2678SDX-3.3/NOPB is 45 V, but the recommended operating range is 8 V to 40 V. Exceeding 40 V continuously may trigger overvoltage stress or reduce reliability; transient spikes up to 45 V are tolerated for short durations per datasheet Section 5.1. Always verify input filtering and clamping in automotive or industrial environments where load dump events occur.
Does LM2678SDX-3.3/NOPB require an external feedback resistor network?
No, LM2678SDX-3.3/NOPB does not require external feedback resistors. As a fixed-output variant, it internally references 3.3 V and expects the FB pin to be connected directly to the output capacitor. This eliminates resistor tolerance errors and simplifies layout - unlike the adjustable LM2678 versions which require two external resistors to set VOUT.
What thermal performance can be expected from LM2678SDX-3.3/NOPB in a standard 4-layer PCB layout?
In a standard 4-layer PCB with 4 in² of 1 oz. copper connected to the exposed thermal pad (DAP), LM2678SDX-3.3/NOPB achieves RθJA ≈ 45°C/W. At 5 A output and 12 V input, typical power dissipation is ~1.8 W, resulting in ~81°C junction rise above ambient - well within the 125°C max rating. For higher ambient or sealed enclosures, adding thermal vias under the DAP further reduces RθJA to ~26°C/W.
Can LM2678SDX-3.3/NOPB be synchronized to an external clock?
No, LM2678SDX-3.3/NOPB cannot be synchronized to an external clock. It uses an internal fixed-frequency 260 kHz oscillator with ±11% tolerance. Unlike newer regulators such as TPS54560, it lacks a SYNC pin or frequency-adjust capability - making it unsuitable for noise-sensitive applications requiring precise EMI frequency placement or multi-rail synchronization.
Is LM2678SDX-3.3/NOPB RoHS-compliant and lead-free?
Yes, LM2678SDX-3.3/NOPB is RoHS-compliant and lead-free. The /NOPB suffix explicitly denotes "No Lead (Pb)-Free" packaging per TI's product marking convention. It meets JEDEC J-STD-020 moisture sensitivity level 3 (MSL-3) and is qualified for lead-free reflow soldering profiles up to 260°C peak temperature.
LM2678SDX-3.3/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):
- 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)
LM2678SDX-3.3/NOPB FAQ
1.How can I place an order for LM2678SDX-3.3/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2678SDX-3.3/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-3.3/NOPB reliable?
The price and inventory of LM2678SDX-3.3/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-3.3/NOPB is usually 5 days.
3.What payment methods are accepted for LM2678SDX-3.3/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2678SDX-3.3/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2678SDX-3.3/NOPB?
LM2678SDX-3.3/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2678SDX-3.3/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-3.3/NOPB?
For technical support, including LM2678SDX-3.3/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2678SDX-3.3/NOPB requirements.
6.How does Aetrix verify that LM2678SDX-3.3/NOPB is sourced from the original manufacturer or authorized distributors?
All LM2678SDX-3.3/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-3.3/NOPB meets industry standards.
7.What is the process for return or replacement of LM2678SDX-3.3/NOPB?
All LM2678SDX-3.3/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM2678SDX-3.3/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-3.3/NOPB part is unused and in its original packaging.
Return procedure for LM2678SDX-3.3/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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