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Texas Instruments LM2678T-3.3
- Part No.:
- LM2678T-3.3
- Manufacturer:
- Texas Instruments
- Package:
- TO-220-7 Formed Leads
- Datasheet:
-
LM2678T-3.3.pdf
- Description:
- IC REG BUCK 3.3V 5A TO220-7
- Quantity:
- Payment:
- Shipping:
Inventory:1,456
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Product details
Overview
LM2678T-3.3 from Texas Instruments is a monolithic 5A step-down (buck) DC/DC voltage regulator with fixed 3.3V output, 260 kHz internal oscillator, 120 mΩ DMOS power switch, and wide 8V–40V input range-designed for high-efficiency power conversion in industrial and embedded systems requiring stable 3.3V rail generation.
For engineers reviewing the LM2678T-3.3 datasheet, LM2678T-3.3 pinout, LM2678T-3.3 application, or LM2678T-3.3 equivalent, key selection criteria include ±2% output tolerance over line/load/temperature, 50 μA standby current in shutdown mode, thermal shutdown and current limiting protection, and compatibility with standard off-the-shelf inductors and Schottky diodes per SIMPLE SWITCHER® design methodology.
Technical Context
The LM2678T-3.3 implements a fixed-frequency pulse-width modulation (PWM) control architecture with an internal 260 kHz oscillator and cycle-by-cycle current limiting. Its integrated 120 mΩ DMOS switch enables up to 5A continuous output current while maintaining >90% efficiency at typical operating points (e.g., 82% at VIN = 12V, IOUT = 5A).
It features a dedicated ON/OFF control pin with 0.8V–2.0V threshold, feedback amplifier with 1.21V reference (internal for fixed versions), and boost capacitor circuitry to enhance gate drive-ensuring low conduction losses and stable operation across −40°C to +125°C junction temperature.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3V ±2% over full line, load, and temperature range-guarantees stable logic supply without external resistor network. |
| Max Output Current | 5A continuous-supports high-current digital loads such as microcontrollers, FPGAs, and interface ICs without external current boosting. |
| Input Voltage Range | 8V to 40V-enables direct use with 12V/24V industrial bus rails and battery-backed systems after pre-regulation. |
| Switching Frequency | 260 kHz ±11%-enables use of compact, low-cost off-the-shelf inductors (e.g., 10 µH) and reduces EMI compared to higher-frequency alternatives. |
| Efficiency | 82% at VIN = 12V, IOUT = 5A-minimizes thermal dissipation in enclosed or thermally constrained environments. |
| Standby Current | 50 µA when ON/OFF pin ≤ 0.8V-enables low-power system sleep modes without auxiliary LDOs or external switches. |
| Thermal Protection | Integrated thermal shutdown-prevents damage during overload or poor heatsinking; auto-recovery upon cooling. |
Pinout & Package
LM2678T-3.3 is packaged in TO-220-7 (Package Number NDZ0007B), featuring a vertical-mount through-hole configuration with exposed tab for thermal relief. The package includes integral heatsink capability and supports PCB copper area for enhanced thermal performance (θJA = 45°C/W with 4 in² copper).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VSW (Pin 1) | Switch Node | Drives external catch diode and inductor; swings between VIN and ~−0.5V (Schottky drop); requires low-inductance layout to minimize ringing. |
| VIN (Pin 2) | Power Input | Supplies internal bias and switch driver; must be bypassed with ≥100 µF electrolytic + 0.1 µF ceramic near pin for stability and transient response. |
| CBOOST (Pin 3) | Bootstrap Capacitor | Connects to VSW; provides gate overdrive for internal MOSFET; 0.01 µF/50V ceramic required for full RDS(ON) reduction. |
| GND (Pin 4) | Power Ground | Common return for switch, feedback, and bias circuits; requires low-impedance ground plane to avoid noise coupling into FB path. |
| FB (Pin 6) | Feedback Input | Internally connected to 3.3V divider; no external resistors needed-simplifies layout and eliminates trimming errors. |
| ON/OFF (Pin 7) | Enable Control | Active-high logic input; <0.8V disables regulator, reducing input current to 50 µA; internal 20 µA pull-up allows open-circuit default-on operation. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 120 mΩ DMOS Switch | Eliminates need for external high-side MOSFET and driver, reducing BOM count and board space while enabling 5A output in TO-220 footprint. |
| ±2% Output Tolerance | Ensures compliance with 3.3V I/O standards (e.g., PCIe, USB, ARM cores) across temperature and load without post-production calibration. |
| 260 kHz Fixed-Frequency PWM | Provides predictable EMI profile and simplifies filter design versus variable-frequency or hysteretic controllers. |
| Built-in Thermal Shutdown | Protects against sustained overload or inadequate heatsinking; latches off until junction cools below threshold-no external thermal sensor required. |
| SIMPLE SWITCHER® Design Support | Validated inductor/capacitor/diode combinations and free LM267X Made Simple software enable functional prototype in under 1 hour. |
Applications
| Industrial PLC Power Supply | Embedded System Pre-Regulator |
|---|---|
Use Scenario: Providing clean 3.3V rail to ARM Cortex-M7 MCU, Ethernet PHY, and CAN transceiver in DIN-rail mounted controller. IC Role / Device Role / Timing Role: Primary buck converter delivering regulated 3.3V from 24V DC bus; handles dynamic load steps up to 4A with <100 mV undershoot. Use Value: Eliminates need for discrete MOSFET + controller solution-reducing component count by 6+ parts and improving MTBF via monolithic integration. | Use Scenario: Generating 3.3V intermediate rail from 12V input to feed low-noise LDOs powering ADCs and sensors in data acquisition module. IC Role / Device Role / Timing Role: High-efficiency pre-regulator stepping down 12V to 3.3V before final LDO filtering; operates continuously at 2.5A average load. Use Value: Achieves 82% efficiency at full load-cutting heat generation by >2W versus linear pre-regulation, enabling fanless enclosure design. |
| Automotive Body Control Module | Point-of-Load Converter for FPGA Core |
Use Scenario: Powering microcontroller, LIN transceiver, and LED drivers in 12V vehicle subsystem with cold-crank tolerance. IC Role / Device Role / Timing Role: Input-capable down to 8V supports 6.5V cold-crank condition; ON/OFF pin synchronized to vehicle ignition signal for zero-quiescent standby. Use Value: 50 µA shutdown current meets automotive ISO 16750-2 quiescent drain requirements without external enable logic. | Use Scenario: Delivering 3.3V core voltage to Xilinx Artix-7 FPGA with peak currents up to 4.5A during configuration and burst processing. IC Role / Device Role / Timing Role: Primary switching regulator supplying FPGA VCCO and auxiliary rails; uses 10 µH inductor and 400 µF output capacitance per TI design guidelines. Use Value: Built-in current limit (7A typ.) and thermal shutdown prevent FPGA brownout or latch-up during transient overloads. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2596T-3.3 | 3A max output, 150 kHz switching frequency, higher RDS(ON) (160 mΩ), no CBOOST pin | Lower current capacity; less efficient at >2.5A; requires larger inductor due to lower frequency | Select when cost sensitivity outweighs current headroom and efficiency needs. |
| TPS54560B | 5A, 100V input, adjustable output, 2.5V–60V input range, 2.2 MHz switching, integrated compensation | Wider input range and higher frequency enable smaller magnetics but require more complex loop compensation | Select for high-input-voltage or space-constrained designs where 2.2 MHz operation justifies added design effort. |
Compared with LM2678T-3.3, LM2596T-3.3 offers lower cost but sacrifices 40% current capability and thermal margin, while TPS54560B delivers greater flexibility and density at the expense of design simplicity and fixed-output convenience.
Availability
LM2678T-3.3 is available at Aetrix Electronics and suitable for industrial automation, embedded computing, and automotive body electronics requiring stable component supply, long-term lifecycle support, and proven thermal reliability in TO-220 packages.
Supply support for LM2678T-3.3 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® portfolio-designed specifically to simplify high-current DC/DC buck regulator implementation using minimal external components and validated reference designs.
FAQ
What is the maximum input voltage rating for LM2678T-3.3?
The absolute maximum input voltage for LM2678T-3.3 is 45V, but the recommended operating range is 8V to 40V per the datasheet. Exceeding 40V risks violating safe operating area limits of the internal DMOS switch and may trigger overvoltage stress not covered by production testing. For reliable long-term operation, maintain VIN ≤ 40V with appropriate derating for transients.
Does LM2678T-3.3 require an external feedback resistor network?
No, LM2678T-3.3 does not require external feedback resistors because it is a fixed-output variant-the 3.3V regulation is achieved using internal precision resistor dividers connected to the FB pin. This eliminates tuning errors, reduces component count, and improves stability versus adjustable versions like LM2678-ADJ.
Can LM2678T-3.3 operate without the CBOOST capacitor?
No, LM2678T-3.3 requires the 0.01 µF ceramic CBOOST capacitor connected between Pin 3 (CBOOST) and Pin 1 (VSW). Omitting it prevents proper gate overdrive of the internal DMOS switch, resulting in elevated RDS(ON), reduced efficiency, thermal runaway, and potential failure under load. TI specifies this capacitor as mandatory in all operating conditions.
What thermal performance can be expected from LM2678T-3.3 in TO-220 package?
In the TO-220-7 package (NDZ0007B), LM2678T-3.3 achieves θJA = 45°C/W with 4 in² of 1 oz. copper on the PCB-enabling ~5A continuous operation at ambient ≤ 60°C with no heatsink. With minimal copper (no external heatsink), θJA rises to 65°C/W, limiting full-load operation to ≤ 45°C ambient. Derating curves in the datasheet confirm 5A capability up to +125°C junction temperature.
Is LM2678T-3.3 RoHS compliant and lead-free?
Yes, LM2678T-3.3 is RoHS compliant and lead-free per TI's official product change notices and packaging specifications. The TO-220-7 package uses matte tin lead finish and complies with JEDEC J-STD-020 moisture sensitivity level (MSL) 1. Full compliance documentation-including substance declarations and test reports-is available via TI's Quality & Environmental page for LM2678T-3.3.
LM2678T-3.3 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- SIMPLE SWITCHER®
- Package/Case:
- TO-220-7 Formed Leads
- Packaging:
- Tube
- Product Status:
- Obsolete
- 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:
- Through Hole
- Supplier Device Package:
- TO-220-7
LM2678T-3.3 FAQ
1.How can I place an order for LM2678T-3.3 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2678T-3.3 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 LM2678T-3.3 reliable?
The price and inventory of LM2678T-3.3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2678T-3.3 is usually 5 days.
3.What payment methods are accepted for LM2678T-3.3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2678T-3.3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2678T-3.3?
LM2678T-3.3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2678T-3.3 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 LM2678T-3.3?
For technical support, including LM2678T-3.3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2678T-3.3 requirements.
6.How does Aetrix verify that LM2678T-3.3 is sourced from the original manufacturer or authorized distributors?
All LM2678T-3.3 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 LM2678T-3.3 meets industry standards.
7.What is the process for return or replacement of LM2678T-3.3?
All LM2678T-3.3 units undergo pre-shipment inspection (PSI). If there is an issue with LM2678T-3.3, 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 LM2678T-3.3 part is unused and in its original packaging.
Return procedure for LM2678T-3.3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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