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Texas Instruments LM2678SX-5.0/NOPB
- Part No.:
- LM2678SX-5.0/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- TO-263-8, D2PAK (7 Leads + Tab), TO-263CA
- Datasheet:
-
LM2678SX-5.0/NOPB.pdf
- Description:
- IC REG BUCK 5V 5A TO263
- Quantity:
- Payment:
- Shipping:
Inventory:1,141
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Product details
Overview
LM2678SX-5.0/NOPB from Texas Instruments is a monolithic step-down (buck) DC-DC switching regulator delivering up to 5 A output current with fixed 5 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 LM2678SX-5.0/NOPB datasheet, LM2678SX-5.0/NOPB pinout, LM2678SX-5.0/NOPB application, or LM2678SX-5.0/NOPB equivalent, key selection criteria include input voltage range compatibility, thermal performance in TO-263-7 packaging, feedback configuration for fixed-output use, and standby current behavior during enable/disable sequencing.
Technical Context
The LM2678SX-5.0/NOPB implements a voltage-mode PWM controller with internal 260 kHz oscillator and integrated 120 mΩ DMOS high-side switch. Its fixed 5 V output eliminates external feedback resistors, simplifying layout while maintaining ±2% regulation across –40°C to 125°C junction temperature.
It features dedicated boot-strap capacitor (CB) pin for gate drive enhancement, ON/OFF pin with 1.4 V threshold and 50 µA standby current, and thermal shutdown/current limiting protection. The device operates only in continuous conduction mode at full load and requires external Schottky catch diode and LC filter components.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 5.0 V, ±2% tolerance over full line, load, and temperature (–40°C to 125°C) |
| Input Voltage Range | 8 V to 40 V - supports wide-range industrial and battery-derived inputs without pre-regulation |
| Max Output Current | 5 A - sustained delivery with proper PCB copper area and thermal management |
| Switching Frequency | 260 kHz ±11% - enables use of standard off-the-shelf inductors and reduces EMI filtering complexity |
| Efficiency | Up to 84% at VIN = 12 V, IOUT = 5 A - achieved via low RDS(ON) 120 mΩ DMOS switch |
| Standby Current | 50 µA typical when ON/OFF pin = 0 V - enables ultra-low-power system sleep states |
| Thermal Shutdown | Integrated protection activates above 165°C junction temperature - prevents damage under overload or poor heatsinking |
Pinout & Package
LM2678SX-5.0/NOPB is supplied in KTW (TO-263-7) package: 10.1 mm × 15.24 mm outline, exposed thermal pad (DAP) connected to GND, rated RθJA = 35°C/W with 0.4896 in² copper area.
| 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 - high dv/dt node requiring tight layout |
| 2 (VIN) | Input supply | Main power input (8–40 V); must be bypassed with low-ESR capacitor placed adjacent to pin - path to GND must be shortest possible |
| 3 (CB) | Bootstrap capacitor | Connects 100 nF ceramic capacitor to SW pin to generate gate drive voltage > VIN for full FET enhancement |
| 4 (GND) | Power ground | Primary return for input/output capacitors and thermal pad; must connect directly to large copper plane for thermal and noise control |
| 5 (NC) | No connect | Internally unconnected - leave floating or tie to GND per layout best practice; no circuit function |
| 6 (FB) | Feedback input | Internally tied to 5 V reference - connect directly to output capacitor for fixed-output operation; no external divider required |
| 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 allows open-circuit enable |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 120 mΩ DMOS switch | Enables 5 A output without external MOSFET; reduces BOM count and layout area versus controller-only solutions |
| Fixed 5 V output configuration | Eliminates external feedback resistor network - improves accuracy, reduces drift, and simplifies production calibration |
| 260 kHz fixed-frequency PWM | Allows predictable EMI spectrum and consistent inductor sizing; avoids frequency jitter issues seen in variable-frequency regulators |
| ON/OFF pin with 50 µA standby | Supports system-level power sequencing and deep-sleep modes without external logic or LDO gating |
| Thermal shutdown + current limit | Self-protecting under short-circuit or overheating; eliminates need for external fault monitoring circuitry in basic applications |
Applications
| Industrial PLC Power Supply | Automotive Body Control Module |
|---|---|
Use Scenario: Primary 5 V rail generation from 12–24 V battery or bus in programmable logic controllers with high ambient temperature exposure. IC Role / Device Role / Timing Role: Main buck regulator providing stable 5 V for microcontroller, I/O drivers, and communication interfaces. Use Value: Delivers 5 A continuously at 125°C junction temperature using TO-263 thermal pad and 0.49 in² copper, meeting IPC-2221 Class 2 reliability requirements. | Use Scenario: Local 5 V supply for CAN transceivers, sensor signal conditioning, and LED drivers in body electronics modules. IC Role / Device Role / Timing Role: Point-of-load regulator converting vehicle battery voltage to clean 5 V with fast transient response to load steps. Use Value: 50 µA shutdown current extends battery life during vehicle sleep mode; ±2% output tolerance ensures robust interface timing margins. |
| Medical Diagnostic Equipment | Test & Measurement Instrumentation |
Use Scenario: Isolated auxiliary 5 V rail powering analog front-end ADCs and precision op-amps in portable ultrasound or ECG units. IC Role / Device Role / Timing Role: High-efficiency preregulator feeding low-noise LDOs that supply sensitive analog circuitry. Use Value: 84% efficiency at 5 A minimizes heat rise in sealed enclosures; fixed 5 V output eliminates resistor tolerance errors affecting measurement accuracy. | Use Scenario: Benchtop power supply subsystem generating stable 5 V for FPGA configuration, memory, and digital logic in automated test equipment. IC Role / Device Role / Timing Role: Main system rail regulator supporting dynamic load changes during pattern generation and data acquisition bursts. Use Value: 260 kHz switching enables compact 10 µH inductor selection; CB pin ensures reliable gate drive across input range, preventing dropout during brownout events. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2596SX-5.0/NOPB | 3 A max output, 150 kHz switching, higher RDS(ON) (220 mΩ), no CB pin - uses charge-pump gate drive | Limited to lower-current applications; less efficient at 5 A; requires larger inductor due to lower frequency | Select when cost sensitivity outweighs current capability and thermal constraints allow smaller solution size |
| TPS54560RGTT | 5.5 A max, 100–2500 kHz adjustable frequency, 95 mΩ RDS(ON), integrated compensation - requires external FB divider even for 5 V | Higher flexibility for EMI tuning and layout optimization; needs design effort for loop stability vs. LM2678's fixed compensation | Select when programmable frequency, tighter thermal limits, or multi-rail synchronization are required |
Compared with LM2596SX-5.0/NOPB, LM2678SX-5.0/NOPB delivers 67% higher current with better thermal margin in same package footprint; versus TPS54560RGTT, it trades configurability for plug-and-play simplicity and reduced external component count in fixed 5 V designs.
Availability
LM2678SX-5.0/NOPB is available at Aetrix Electronics and suitable for industrial PLC power supplies, automotive body control modules, and medical diagnostic equipment requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LM2678SX-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 company headquartered in Dallas, Texas, specializing in analog and embedded processing technologies with broad industrial, automotive, and personal electronics reach.
The LM2678 series belongs to TI's SIMPLE SWITCHER® power converter family, designed specifically to simplify high-efficiency DC-DC buck regulator implementation using minimal external components and standardized magnetics.
FAQ
What is the maximum input voltage rating for LM2678SX-5.0/NOPB?
The absolute maximum input voltage for LM2678SX-5.0/NOPB is 45 V, but the recommended operating range is 8 V to 40 V. Operation above 40 V risks exceeding safe SOA limits and may trigger overvoltage protection or cause permanent damage. Designers should maintain at least 1 V margin below 45 V and verify transient clamping on the input rail per Section 5.1 of the SNVS029L datasheet. LM2678SX-5.0/NOPB must never be subjected to sustained input above 40 V.
Does LM2678SX-5.0/NOPB require an external feedback resistor network?
No, LM2678SX-5.0/NOPB does not require external feedback resistors because it is a fixed 5 V output variant. Pin 6 (FB) is internally connected to the 5 V reference, so it must be connected directly to the output capacitor's positive terminal. Adding external resistors would disrupt regulation and is explicitly prohibited in the datasheet's Figure 7-2 and Section 6.3.5. LM2678SX-5.0/NOPB achieves ±2% output accuracy without trimming or calibration.
What thermal performance can be expected from LM2678SX-5.0/NOPB in TO-263-7 package?
In the KTW (TO-263-7) package, LM2678SX-5.0/NOPB achieves RθJA = 35°C/W with 0.4896 in² (3.6× package area) of 1 oz. copper, and 26°C/W with 1.0064 in² (7.4× package area). At 5 A output and 12 V input, typical power dissipation is ~1.8 W; with 35°C/W, junction rise is ~63°C above ambient. LM2678SX-5.0/NOPB includes thermal shutdown at ~165°C, making adequate copper area essential for continuous 5 A operation at elevated ambient temperatures.
Can LM2678SX-5.0/NOPB be synchronized to an external clock?
No, LM2678SX-5.0/NOPB cannot be synchronized to an external clock. It uses an internal fixed-frequency 260 kHz oscillator with ±11% tolerance and no external sync pin or frequency adjustment capability. This differs from newer regulators like TPS54560 or LM5115. For EMI-sensitive systems requiring clock synchronization, designers must select an alternative part - LM2678SX-5.0/NOPB's architecture prioritizes simplicity and minimum external components over timing flexibility.
What is the purpose of the CB pin on LM2678SX-5.0/NOPB?
The CB (bootstrap capacitor) pin on LM2678SX-5.0/NOPB provides gate drive voltage for the internal high-side DMOS switch. A 100 nF ceramic capacitor must be connected between CB and SW (pin 1) to generate a voltage ~VIN + 5 V, ensuring full enhancement of the FET and minimizing conduction losses. Omitting or undersizing this capacitor causes erratic switching, excessive heating, and potential failure. LM2678SX-5.0/NOPB will not regulate correctly without proper CB capacitor placement and routing.
LM2678SX-5.0/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- SIMPLE SWITCHER®
- Package/Case:
- TO-263-8, D2PAK (7 Leads + Tab), TO-263CA
- 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:
- TO-263 (DDPAK-7)
LM2678SX-5.0/NOPB FAQ
1.How can I place an order for LM2678SX-5.0/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2678SX-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 LM2678SX-5.0/NOPB reliable?
The price and inventory of LM2678SX-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 LM2678SX-5.0/NOPB is usually 5 days.
3.What payment methods are accepted for LM2678SX-5.0/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2678SX-5.0/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2678SX-5.0/NOPB?
LM2678SX-5.0/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2678SX-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 LM2678SX-5.0/NOPB?
For technical support, including LM2678SX-5.0/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2678SX-5.0/NOPB requirements.
6.How does Aetrix verify that LM2678SX-5.0/NOPB is sourced from the original manufacturer or authorized distributors?
All LM2678SX-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 LM2678SX-5.0/NOPB meets industry standards.
7.What is the process for return or replacement of LM2678SX-5.0/NOPB?
All LM2678SX-5.0/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM2678SX-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 LM2678SX-5.0/NOPB part is unused and in its original packaging.
Return procedure for LM2678SX-5.0/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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