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Texas Instruments LM2678SD-3.3/NOPB
- Part No.:
- LM2678SD-3.3/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- 14-VDFN Exposed Pad
- Datasheet:
-
LM2678SD-3.3/NOPB.pdf
- Description:
- IC REG BUCK 3.3V 5A 14VSON
- Quantity:
- Payment:
- Shipping:
Inventory:744
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Product details
Overview
LM2678SD-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, 8–40 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 LM2678SD-3.3/NOPB datasheet, LM2678SD-3.3/NOPB pinout, LM2678SD-3.3/NOPB application, or LM2678SD-3.3/NOPB equivalent, key selection criteria include its 3.3 V fixed output accuracy, thermal shutdown protection, 50 µA standby current, and compatibility with standard off-the-shelf inductors and Schottky diodes in compact PCB layouts.
Technical Context
The LM2678SD-3.3/NOPB implements a voltage-mode PWM controller with a fixed 260 kHz oscillator driving an integrated 120 mΩ DMOS high-side switch. Its feedback loop uses internal resistive divider for 3.3 V regulation, eliminating external resistor networks - simplifying design while maintaining ±2% output tolerance across –40°C to 125°C junction temperature.
Functional modes include active regulation (ON/OFF ≥ 1.4 V) and shutdown (ON/OFF ≤ 0.8 V), drawing only 50 µA quiescent current. Thermal shutdown and cycle-by-cycle current limiting (6.1–8.3 A) provide robust fault protection without external circuitry.
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 battery-derived inputs without pre-regulation |
| Max Output Current | 5 A continuous - enables single-chip conversion for mid-power embedded systems |
| Switching Frequency | 260 kHz ±11% - enables use of compact, standardized inductors and reduces EMI filtering burden |
| Efficiency | Up to 92% (at 12 VIN/5 A load for 12 V version; 82% typical for 3.3 V version at same conditions) |
| Standby Current | 50 µA max - enables ultra-low-power system sleep states without external disconnect |
| RDS(ON) | 0.12 Ω typ (25°C) - minimizes conduction loss and thermal rise under full load |
Pinout & Package
LM2678SD-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 optimal thermal performance (RθJA = 35°C/W with 0.4896 in² copper).
| 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 waveform |
| 2 (VIN) | Input supply | Main power input (8–40 V); requires low-ESR bypass capacitor placed adjacent to minimize high-frequency ringing |
| 3 (CB) | Bootstrap capacitor | Connects to SW via 100 nF ceramic capacitor to generate gate drive voltage > VIN for full FET enhancement |
| 4 (GND) | Power ground | Primary return path for input/output capacitors and thermal pad - must tie directly to low-impedance ground plane |
| 5 (NC) | No connect | Internally unconnected; must remain floating - no routing or soldering allowed |
| 6 (FB) | Feedback sense | Internally tied to 3.3 V divider - connect directly to output capacitor for fixed-output operation; no external resistors needed |
| 7 (ON/OFF) | Enable control | Logic-level input: ≥1.4 V = ON, ≤0.8 V = OFF; internal 20 µA pull-up allows simple open-drain or microcontroller GPIO control |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 120 mΩ DMOS switch | Eliminates need for external MOSFET and driver, reducing BOM count and layout complexity |
| Fixed 3.3 V output with internal feedback divider | Removes external resistor network, improving accuracy and reducing board space vs adjustable versions |
| 260 kHz fixed-frequency PWM | Enables predictable EMI spectrum and consistent inductor sizing across designs |
| Thermal shutdown + current limiting | Provides autonomous fault recovery without external sensing or protection ICs |
| 50 µA shutdown quiescent current | Supports battery-backed or energy-harvesting applications requiring multi-day standby |
Applications
| Industrial PLC Power Supply | Embedded System Preregulator |
|---|---|
Use Scenario: Providing stable 3.3 V rail for microcontrollers and I/O peripherals in programmable logic controllers operating from 24 V DC field buses. IC Role / Device Role / Timing Role: Primary buck converter delivering regulated 3.3 V at up to 5 A with high efficiency and thermal resilience in enclosed cabinets. Use Value: Eliminates need for discrete MOSFET + controller solutions, reducing footprint and qualification effort while meeting IEC 61000-4 immunity requirements via predictable 260 kHz switching. | Use Scenario: Generating clean 3.3 V intermediate bus from 12 V or 24 V input to feed LDOs powering sensitive analog or RF subsystems. IC Role / Device Role / Timing Role: High-efficiency preregulator minimizing heat generation before final low-noise linear regulation. Use Value: Achieves >82% efficiency at full load, cutting thermal load on downstream LDOs and enabling smaller heatsinks in space-constrained modules. |
| Battery Charger Auxiliary Rail | Test Equipment Power Module |
Use Scenario: Supplying 3.3 V logic power to charge management ICs and status LEDs in portable Li-ion battery chargers powered from 9–36 V adapters. IC Role / Device Role / Timing Role: Standby-capable buck regulator enabling charger sleep mode with <50 µA system drain. Use Value: ON/OFF pin allows microcontroller-directed power gating, extending battery life during idle periods without sacrificing fast wake-up response. | Use Scenario: Delivering precise 3.3 V at 5 A for digital signal processing boards in automated test equipment with strict thermal and ripple requirements. IC Role / Device Role / Timing Role: Main DC-DC stage with tight ±2% output tolerance and low output impedance to support dynamic FPGA core loads. Use Value: Internal feedback ensures stable regulation under rapid load transients (500 mA → 5 A), reducing need for large bulk capacitance and easing layout constraints. |
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 and 3.3 V fixed output; identical pinout and package | Suitable for sub-3 A loads where thermal margin or cost reduction is prioritized | Select when full 5 A capability is unnecessary - reduces thermal design complexity and component cost |
| TPS54560QDGQRQ1 | Automotive-grade (AEC-Q100), 60 V max input, adjustable output, 5 A, 2.2 MHz switching - different pinout and control architecture | Required for automotive environments or higher input voltage ranges beyond 40 V | Choose only if AEC-Q100 qualification or >40 V input is mandatory; not drop-in compatible |
Compared with LM2678SD-3.3/NOPB, LM2675SD-3.3/NOPB offers identical functionality at reduced current capacity and lower thermal demand, while TPS54560QDGQRQ1 provides automotive reliability and wider input range but requires redesign due to non-pin-compatible layout and adjustable feedback architecture.
Availability
LM2678SD-3.3/NOPB is available at Aetrix Electronics and suitable for industrial PLC power supplies, embedded system preregulators, battery charger auxiliary rails, and test equipment power modules requiring stable component supply and long-term manufacturability.
Supply support for LM2678SD-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 to simplify high-efficiency DC-DC buck converter implementation using minimal external components and industry-standard magnetics.
FAQ
What is the maximum input voltage rating for LM2678SD-3.3/NOPB?
The absolute maximum input voltage for LM2678SD-3.3/NOPB is 45 V, but the recommended operating range is 8 V to 40 V. Exceeding 40 V risks violating safe operating area limits and may trigger overvoltage protection or reduce long-term reliability. Designs should maintain at least 5 V headroom below 45 V for transient suppression margins.
Does LM2678SD-3.3/NOPB require external feedback resistors?
No, LM2678SD-3.3/NOPB does not require external feedback resistors. It features an internal precision voltage divider optimized for 3.3 V output, so the FB pin (Pin 6) must be connected directly to the output capacitor. Adding external resistors would disrupt regulation and void the ±2% output tolerance specification.
What thermal performance can be expected from LM2678SD-3.3/NOPB in a standard PCB layout?
With the KTW (TO-263) package mounted on a 0.4896 in² (3.6× package area) 1 oz. copper plane, LM2678SD-3.3/NOPB achieves RθJA = 35°C/W. At 5 A output and 12 V input, typical power dissipation is ~1.8 W, resulting in ~63°C junction-to-ambient rise - well within the –40°C to 125°C operating range when ambient stays below 62°C.
Can LM2678SD-3.3/NOPB be synchronized to an external clock?
No, LM2678SD-3.3/NOPB cannot be synchronized to an external clock. It uses an internal fixed-frequency 260 kHz oscillator with ±11% tolerance. There is no SYNC pin or frequency-adjust capability - designs requiring synchronization must select alternatives like the TPS54560 or LM5116.
Is LM2678SD-3.3/NOPB RoHS compliant and lead-free?
Yes, LM2678SD-3.3/NOPB is RoHS compliant and lead-free. The "/NOPB" suffix explicitly denotes lead-free packaging per JEDEC J-STD-609, with matte tin lead finish and halogen-free molding compound - certified to meet EU RoHS Directive 2011/65/EU and REACH SVHC requirements.
LM2678SD-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)
LM2678SD-3.3/NOPB FAQ
1.How can I place an order for LM2678SD-3.3/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2678SD-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 LM2678SD-3.3/NOPB reliable?
The price and inventory of LM2678SD-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 LM2678SD-3.3/NOPB is usually 5 days.
3.What payment methods are accepted for LM2678SD-3.3/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2678SD-3.3/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2678SD-3.3/NOPB?
LM2678SD-3.3/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2678SD-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 LM2678SD-3.3/NOPB?
For technical support, including LM2678SD-3.3/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2678SD-3.3/NOPB requirements.
6.How does Aetrix verify that LM2678SD-3.3/NOPB is sourced from the original manufacturer or authorized distributors?
All LM2678SD-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 LM2678SD-3.3/NOPB meets industry standards.
7.What is the process for return or replacement of LM2678SD-3.3/NOPB?
All LM2678SD-3.3/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM2678SD-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 LM2678SD-3.3/NOPB part is unused and in its original packaging.
Return procedure for LM2678SD-3.3/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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