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Texas Instruments LM2678SX-ADJ/NOPB
- Part No.:
- LM2678SX-ADJ/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- TO-263-8, D2PAK (7 Leads + Tab), TO-263CA
- Datasheet:
-
LM2678SX-ADJ/NOPB.pdf
- Description:
- IC REG BUCK ADJ 5A TO263
- Quantity:
- Payment:
- Shipping:
Inventory:1,308
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Product details
Overview
LM2678SX-ADJ/NOPB from Texas Instruments is a monolithic step-down (buck) DC-DC switching regulator delivering up to 5 A output current with adjustable output voltage (1.2 V to 37 V), 260 kHz fixed-frequency operation, and 8 V–40 V input range. It integrates a 120 mΩ DMOS high-side switch and supports thermal shutdown, current limiting, and ON/OFF control-used in industrial power supplies requiring high-efficiency (>90%) local regulation.
For engineers reviewing the LM2678SX-ADJ/NOPB datasheet, LM2678SX-ADJ/NOPB pinout, LM2678SX-ADJ/NOPB application, or LM2678SX-ADJ/NOPB equivalent, key selection criteria include feedback voltage tolerance (±2%), standby current (50 µA), RDS(ON) (0.12 Ω typ), oscillator frequency stability (±11%), and TO-263-7 package thermal performance.
Technical Context
The LM2678SX-ADJ/NOPB implements a fixed-frequency PWM controller with internal 260 kHz oscillator driving a high-side DMOS switch. Its feedback loop senses output voltage via external resistor divider at FB pin and regulates using error amplifier and pulse-width modulation-supporting continuous or discontinuous conduction modes depending on load and inductor selection.
It features dedicated bootstrapping (CB pin), thermally enhanced TO-263-7 (KTW) package with exposed DAP grounded for thermal management, and integrated protection including current limit (6.1–8.3 A), thermal shutdown, and ON/OFF logic with 1.4 V threshold and 50 µA standby draw.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output current | Up to 5 A continuous-supports high-power local regulation without external pass devices. |
| Input voltage range | 8 V to 40 V-enables direct use with 12 V/24 V industrial buses and battery systems. |
| Output voltage range | Adjustable 1.2 V to 37 V-set via external resistor divider on FB pin; supports wide system rail flexibility. |
| Feedback voltage | 1.21 V ±1.1% (typ)-defines output setpoint accuracy; enables ±2% total output tolerance over line/load/temp. |
| Switch RDS(ON) | 0.12 Ω (25°C)-minimizes conduction loss at full load, enabling >90% efficiency at 5 A. |
| Oscillator frequency | 260 kHz ±11%-fixed timing enables predictable EMI profile and simplifies filter design with standard off-the-shelf inductors. |
| Standby current | 50 µA (25°C)-achieved by pulling ON/OFF pin low; critical for low-power sleep modes in battery-backed systems. |
Pinout & Package
LM2678SX-ADJ/NOPB uses the KTW (TO-263-7) thermally enhanced surface-mount package with exposed DAP connected to GND for improved heat dissipation. Dimensions: 10.1 mm × 15.24 mm. The DAP must be soldered to a PCB ground plane with thermal vias for optimal junction-to-ambient performance (RθJA = 35°C/W with 0.4896 in² copper).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (SW) | Switch output | Drain node of internal high-side 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); supplies both load path and internal bias-requires low-ESR input capacitor placed adjacent to pin. |
| 3 (CB) | Bootstrap capacitor | Connects to SW pin via 100 nF ceramic capacitor to generate gate drive voltage > VIN for full FET enhancement. |
| 4 (GND) | Power ground | Main return path for IN, SW, and FB circuits; must tie to low-impedance ground plane and connect DAP directly. |
| 5 (NC) | No connect | Internally unconnected-must remain floating; no routing or soldering required. |
| 6 (FB) | Feedback sense | High-impedance input (85 nA bias) to error amplifier; sets output voltage via external resistor divider-sensitive to noise coupling. |
| 7 (ON/OFF) | Enable control | Logic-level input: ≥1.4 V enables regulation; ≤0.8 V disables with 50 µA quiescent draw-supports microcontroller-controlled power sequencing. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 120 mΩ DMOS switch | Eliminates need for external high-current MOSFET and driver, reducing BOM count and layout complexity. |
| 260 kHz fixed-frequency PWM | Enables consistent EMI filtering and predictable inductor sizing-compatible with TI's family of standard buck inductors. |
| ±2% output tolerance over line/load/temp | Ensures stable downstream logic and analog circuit operation without post-regulation trimming. |
| Thermal shutdown + current limiting | Protects against overload, short-circuit, and ambient overheating-latches off until reset by cycling ON/OFF pin. |
| WEBENCH® Power Designer support | Provides automated schematic generation, component selection, efficiency simulation, and BOM export-reducing design cycle time. |
Applications
| Industrial PLC Power Supply | Battery-Powered Test Equipment |
|---|---|
Use Scenario: Local 3.3 V or 5 V rail generation from 24 V DC bus in programmable logic controller backplane. IC Role / Device Role / Timing Role: Primary step-down regulator delivering regulated power to FPGA, microcontroller, and I/O drivers. Use Value: High efficiency (>90%) minimizes heat buildup in enclosed chassis; 5 A capability supports multiple subsystems from single IC. | Use Scenario: Portable multimeter or oscilloscope with rechargeable Li-ion battery (8–16 V) powering mixed-signal analog and digital sections. IC Role / Device Role / Timing Role: Adjustable-output buck converter generating precise 1.8 V, 3.3 V, or 5 V rails under variable battery voltage. Use Value: 50 µA standby current extends battery life during idle; ±2% output tolerance ensures ADC reference stability. |
| Telecom Line Card Preregulator | Automotive Body Control Module |
Use Scenario: Intermediate 5 V rail generation from 48 V telecom supply before LDOs feed sensitive PHY and SerDes circuits. IC Role / Device Role / Timing Role: High-current preregulator reducing voltage differential across downstream linear regulators. Use Value: 8–40 V input range accommodates 48 V nominal with transients; 260 kHz switching avoids AM radio band interference. | Use Scenario: Central body controller converting vehicle battery (9–16 V) to 5 V for microcontroller, CAN transceivers, and sensor interfaces. IC Role / Device Role / Timing Role: Main DC-DC converter enabling cold-crank operation down to 8 V input while maintaining regulated output. Use Value: −40°C to 125°C junction rating meets automotive AEC-Q100 requirements; ON/OFF pin allows MCU-controlled power gating. |
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-ADJ/NOPB | 3 A output current, 150 kHz switching frequency, higher RDS(ON) (0.22 Ω), wider input range (4.5–40 V) | Lower power density; less suitable for 5 A continuous loads or space-constrained layouts | Prefer when cost sensitivity outweighs current demand or when lower EMI is prioritized over size. |
| TPS54560QDGQRQ1 | 5 A output, 100 V max input, 2.5–60 V input range, 100 kHz–2.5 MHz adjustable frequency, integrated soft-start | Higher voltage capability and frequency flexibility-but requires more external components and layout care | Choose for automotive 12 V systems with load dump transients or designs needing programmable frequency for EMI tuning. |
Compared with LM2678SX-ADJ/NOPB, LM2596SX-ADJ/NOPB offers lower cost and simpler layout but sacrifices 40% output current headroom and thermal margin; TPS54560QDGQRQ1 provides superior transient robustness and frequency agility but increases design complexity and bill-of-materials count.
Availability
LM2678SX-ADJ/NOPB is available at Aetrix Electronics and suitable for industrial PLC power supplies, battery-powered test equipment, telecom line card preregulators, and automotive body control modules requiring stable component supply and long-term production continuity.
Supply support for LM2678SX-ADJ/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 where minimal external components, fast time-to-market, and proven thermal reliability are critical.
FAQ
What is the maximum output current supported by the LM2678SX-ADJ/NOPB?
The LM2678SX-ADJ/NOPB delivers up to 5 A of continuous output current under proper thermal conditions-achievable using the TO-263-7 package with adequate PCB copper area and thermal vias. Peak current limit is specified from 5.75 A to 8.75 A across temperature, ensuring robust overload protection without external sensing.
How does the LM2678SX-ADJ/NOPB achieve its adjustable output voltage range?
The LM2678SX-ADJ/NOPB achieves adjustable output (1.2 V to 37 V) through its feedback (FB) pin, which senses a resistive divider connected between output and ground. The internal reference is 1.21 V, so VOUT = 1.21 × (1 + R1/R2). This architecture allows precise setting of any output within the range while maintaining ±2% regulation accuracy over line, load, and temperature.
What is the purpose of the CB pin on the LM2678SX-ADJ/NOPB?
Pin 3 (CB) on the LM2678SX-ADJ/NOPB is the bootstrap capacitor connection for the high-side gate driver. A 100 nF ceramic capacitor must be placed between CB and SW pins to generate a gate drive voltage above VIN-ensuring full enhancement of the internal DMOS switch and minimizing RDS(ON) conduction losses for high efficiency.
Can the LM2678SX-ADJ/NOPB operate with an input voltage below 8 V?
No-the LM2678SX-ADJ/NOPB has a minimum recommended input voltage of 8 V per its absolute operating conditions. Below this, internal bias circuitry cannot sustain regulation, and the device may fail to start or exhibit unstable switching. For sub-8 V inputs, alternative regulators such as the TPS543x series or LM2675 should be evaluated.
What thermal considerations apply to the LM2678SX-ADJ/NOPB in TO-263-7 package?
The LM2678SX-ADJ/NOPB in KTW (TO-263-7) package requires connection of its exposed DAP to a large PCB ground plane with thermal vias. With 0.4896 in² copper, RθJA is 35°C/W; without copper, it rises to 56°C/W. Junction temperature must stay ≤125°C-so at 5 A and 12 V input, derating or forced airflow may be needed above ambient >60°C.
LM2678SX-ADJ/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:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 8V
- Voltage - Input (Max):
- 40V
- Voltage - Output (Min/Fixed):
- 1.21V
- Voltage - Output (Max):
- 37V
- 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-ADJ/NOPB FAQ
1.How can I place an order for LM2678SX-ADJ/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2678SX-ADJ/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-ADJ/NOPB reliable?
The price and inventory of LM2678SX-ADJ/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-ADJ/NOPB is usually 5 days.
3.What payment methods are accepted for LM2678SX-ADJ/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2678SX-ADJ/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2678SX-ADJ/NOPB?
LM2678SX-ADJ/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2678SX-ADJ/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-ADJ/NOPB?
For technical support, including LM2678SX-ADJ/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2678SX-ADJ/NOPB requirements.
6.How does Aetrix verify that LM2678SX-ADJ/NOPB is sourced from the original manufacturer or authorized distributors?
All LM2678SX-ADJ/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-ADJ/NOPB meets industry standards.
7.What is the process for return or replacement of LM2678SX-ADJ/NOPB?
All LM2678SX-ADJ/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM2678SX-ADJ/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-ADJ/NOPB part is unused and in its original packaging.
Return procedure for LM2678SX-ADJ/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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