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Texas Instruments LM2678SX-12/NOPB
- Part No.:
- LM2678SX-12/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- TO-263-8, D2PAK (7 Leads + Tab), TO-263CA
- Datasheet:
-
LM2678SX-12/NOPB.pdf
- Description:
- IC REG BUCK 12V 5A TO263
- Quantity:
- Payment:
- Shipping:
Inventory:651
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Product details
Overview
LM2678SX-12/NOPB from Texas Instruments is a monolithic step-down (buck) DC-DC switching regulator delivering up to 5 A output current with fixed 12 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 shutdown.
For engineers reviewing the LM2678SX-12/NOPB datasheet, LM2678SX-12/NOPB pinout, LM2678SX-12/NOPB application, or LM2678SX-12/NOPB equivalent, key selection criteria include its 92% peak efficiency at 24 VIN/5 A, thermal shutdown protection, 50 µA standby current, and compatibility with standard off-the-shelf inductors and Schottky diodes in TO-263-7 (KTW) packaging.
Technical Context
The LM2678SX-12/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 precision 1.21 V reference (VFB) and senses output directly at the FB pin for fixed 12 V regulation-no external divider required.
It operates across –40°C to +125°C junction temperature, features cycle-by-cycle current limiting (6.1–8.3 A), thermal shutdown, and ON/OFF pin control with 1.4 V threshold and 20 µA input bias. Standby quiescent current is 50 µA at 25°C, rising to 150 µA over temperature.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 12 V ±2% (TJ = –40°C to 125°C); enables direct connection to 12 V rails without feedback resistors. |
| Input Voltage Range | 8 V to 40 V; supports wide industrial and automotive battery-supplied systems including 12 V, 24 V, and 36 V nominal sources. |
| Max Output Current | 5 A continuous; sufficient for powering FPGAs, motor drivers, and multi-rail power subsystems with margin. |
| Switching Frequency | 260 kHz ±11%; enables use of compact, low-cost off-the-shelf inductors (e.g., 10–22 µH) and reduces EMI compared to higher frequencies. |
| Efficiency | Up to 92% at VIN = 24 V, IOUT = 5 A; minimizes thermal load and improves system-level power density. |
| Quiescent Current | 6 mA typical active mode; drops to 50 µA in shutdown (ON/OFF = 0 V), enabling ultra-low-power standby states. |
| RDS(ON) | 0.12 Ω typical at TJ = 25°C; reduces conduction loss and improves thermal performance under high-current loads. |
Pinout & Package
LM2678SX-12/NOPB is supplied in the KTW (TO-263-7) thermally enhanced surface-mount package (10.1 mm × 15.24 mm), featuring an exposed DAP (die attach pad) connected internally to GND for optimal thermal dissipation and electrical grounding.
| 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; switches between VIN and ~–0.5 V during operation. |
| 2 (VIN) | Input supply | Primary power input (8–40 V); must be bypassed with low-ESR capacitor placed adjacent to pin to suppress high-frequency ripple and ringing. |
| 3 (CB) | Bootstrap capacitor | Connects to SW via 100 nF ceramic capacitor; supplies gate drive voltage above VIN to fully enhance internal high-side FET. |
| 4 (GND) | Power ground | Main return path for input/output capacitors and inductor; requires low-inductance connection to PCB ground plane and DAP. |
| 5 (NC) | No connect | Internally unconnected; must remain floating-no external connection permitted. |
| 6 (FB) | Feedback sense | Direct connection to 12 V output (fixed version); internal resistor divider sets regulation point-no external components needed. |
| 7 (ON/OFF) | Enable control | Logic-level input: ≥1.4 V enables regulation; ≤0.8 V disables output and reduces IQ to 50 µA; internal 20 µA pull-up allows open-circuit enable. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 120 mΩ DMOS switch | Eliminates need for external MOSFET and driver; reduces BOM count and layout complexity while maintaining >90% efficiency at full load. |
| Fixed 12 V output with ±2% tolerance | Guarantees stable rail without calibration or trimming; simplifies design validation and eliminates feedback resistor tolerance errors. |
| 260 kHz fixed-frequency oscillator | Enables predictable EMI profile and consistent inductor sizing; avoids frequency jitter issues seen in variable-frequency controllers. |
| Thermal shutdown & cycle-by-cycle current limit | Protects against overload, short-circuit, and overheating without external circuitry; ensures robust field reliability in unattended systems. |
| 50 µA shutdown quiescent current | Supports battery-backed or energy-harvesting applications requiring multi-week standby life with minimal self-discharge. |
Applications
| Industrial Motor Drive Power Supply | Automotive Body Control Module (BCM) |
|---|---|
Use Scenario: Provides regulated 12 V power to microcontrollers, CAN transceivers, and relay drivers in motor control cabinets operating from 24 V DC bus. IC Role / Device Role / Timing Role: Primary buck converter supplying clean, efficient 12 V rail; handles transient loads up to 5 A during solenoid actuation. Use Value: High efficiency (92%) reduces heatsink requirements; thermal shutdown prevents failure during stall conditions or ambient temperatures up to 125°C. | Use Scenario: Powers MCU, sensors, and LED drivers in vehicle BCMs fed from 12 V battery with cold-crank (up to 40 V) and load-dump (up to 36 V) transients. IC Role / Device Role / Timing Role: Pre-regulator stepping down raw battery voltage to stable 12 V before LDOs; withstands 8–40 V input range and 125°C junction temp. Use Value: ±2% output tolerance ensures reliable sensor/MCU operation; 50 µA shutdown current extends battery life during vehicle sleep mode. |
| Programmable Logic Controller (PLC) I/O Module | Test & Measurement Equipment Power Rail |
Use Scenario: Generates isolated 12 V supply for digital I/O expansion modules in modular PLC chassis with shared 24 V backplane. IC Role / Device Role / Timing Role: Local point-of-load regulator delivering 5 A to multiple optocouplers, level shifters, and interface ICs per slot. Use Value: TO-263-7 package provides superior thermal performance on dense PCBs; fixed 12 V output eliminates calibration overhead during mass production. | Use Scenario: Supplies precision analog front-end circuits (ADCs, op-amps) and FPGA configuration logic in benchtop instruments requiring low-noise, stable 12 V. IC Role / Device Role / Timing Role: Main DC-DC stage feeding low-noise LDOs; operates in continuous conduction mode with <1% output ripple using recommended output capacitor ESR. Use Value: 260 kHz switching frequency allows effective filtering with small LC components; tight VOUT tolerance maintains measurement accuracy across temperature. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2678T-12/NOPB | Same electrical specs but in TO-220-7 (NDZ) package; higher RθJA (45–65°C/W vs. 26–35°C/W for KTW); no exposed DAP. | Suitable for lower-power or forced-air-cooled designs where PCB space permits larger through-hole footprint. | Select when mechanical mounting constraints favor TO-220 or when existing thermal management uses heatsinks rather than PCB copper area. |
| LM2596T-12 | 3 A max output, 150 kHz switching, 0.15 Ω RDS(ON); lacks ON/OFF pin and has looser ±4% output tolerance. | Better suited for cost-sensitive, lower-current applications where 5 A capability and tight regulation are not required. | Choose only if load current remains below 3 A and ±4% output variation is acceptable for downstream circuitry. |
Compared with LM2678T-12/NOPB, LM2678SX-12/NOPB offers superior thermal performance and smaller footprint; versus LM2596T-12, it delivers higher current, tighter regulation, and active enable control-critical for modern embedded systems requiring dynamic power sequencing.
Availability
LM2678SX-12/NOPB is available at Aetrix Electronics and suitable for industrial motor drives, automotive body control modules, and programmable logic controller I/O modules requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LM2678SX-12/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 engineers seeking fast, robust, and low-component-count DC-DC solutions for industrial, automotive, and test equipment applications.
FAQ
What is the maximum input voltage rating for LM2678SX-12/NOPB?
The absolute maximum input voltage for LM2678SX-12/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 cause permanent damage. For automotive applications subject to load dump, ensure external clamping (e.g., TVS) limits transient exposure within this window.
Does LM2678SX-12/NOPB require external feedback resistors?
No. LM2678SX-12/NOPB is the fixed 12 V output variant-its internal feedback divider sets regulation at 12 V ±2%. Pin 6 (FB) must be connected directly to the output capacitor; no external resistors are needed, reducing design risk and component count.
How does the ON/OFF pin function on LM2678SX-12/NOPB?
The ON/OFF pin (Pin 7) enables logic-level control: applying ≥1.4 V turns on regulation; ≤0.8 V forces shutdown with 50 µA quiescent current. The pin has a 20 µA internal pull-up, so leaving it open defaults to enabled operation-no external pull-up resistor is required unless active low control is needed.
What thermal performance can be expected from LM2678SX-12/NOPB in TO-263-7 package?
In the KTW (TO-263-7) package with proper PCB copper area (≥1.0064 in² connected via 12 vias to inner layers), LM2678SX-12/NOPB achieves RθJA = 29°C/W. At 5 A output and 24 V input, junction temperature rise is ~105°C above ambient-well within the –40°C to +125°C rating when ambient stays below 20°C, or with modest airflow.
Can LM2678SX-12/NOPB be used with ceramic output capacitors?
Yes, LM2678SX-12/NOPB supports ceramic output capacitors, but stability requires careful attention to ESR and capacitance value. Use ≥400 µF total output capacitance with ESR ≤13 mΩ (e.g., parallel 220 µF + 100 µF X7R ceramics). Avoid excessively low-ESR (<5 mΩ) configurations without phase compensation, as they may induce oscillation due to zero placement in the control loop.
LM2678SX-12/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):
- 15V
- Voltage - Input (Max):
- 40V
- Voltage - Output (Min/Fixed):
- 12V
- 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-12/NOPB FAQ
1.How can I place an order for LM2678SX-12/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2678SX-12/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-12/NOPB reliable?
The price and inventory of LM2678SX-12/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-12/NOPB is usually 5 days.
3.What payment methods are accepted for LM2678SX-12/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2678SX-12/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2678SX-12/NOPB?
LM2678SX-12/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2678SX-12/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-12/NOPB?
For technical support, including LM2678SX-12/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2678SX-12/NOPB requirements.
6.How does Aetrix verify that LM2678SX-12/NOPB is sourced from the original manufacturer or authorized distributors?
All LM2678SX-12/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-12/NOPB meets industry standards.
7.What is the process for return or replacement of LM2678SX-12/NOPB?
All LM2678SX-12/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM2678SX-12/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-12/NOPB part is unused and in its original packaging.
Return procedure for LM2678SX-12/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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