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Texas Instruments LM2679SX-3.3/NOPB
- Part No.:
- LM2679SX-3.3/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- TO-263-8, D2PAK (7 Leads + Tab), TO-263CA
- Datasheet:
-
LM2679SX-3.3/NOPB.pdf
- Description:
- IC REG BUCK 3.3V 5A TO263
- Quantity:
- Payment:
- Shipping:
Inventory:4,878
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Product details
Overview
LM2679SX-3.3/NOPB from Texas Instruments is a monolithic 5-A step-down (buck) DC/DC voltage regulator with fixed 3.3-V output, 8–40-V input range, 260-kHz fixed-frequency PWM control, and resistor-programmable current limit (5.5–7.6 A typical). It integrates a 120-mΩ DMOS high-side switch and supports soft-start via external capacitor for surge-current limiting in industrial power supplies.
For engineers reviewing the LM2679SX-3.3/NOPB datasheet, LM2679SX-3.3/NOPB pinout, LM2679SX-3.3/NOPB application, or LM2679SX-3.3/NOPB equivalent, key selection criteria include ±2% output tolerance over line/load/temperature, thermal shutdown protection, bootstrapped gate drive architecture, and TO-263-7 package compatibility with high-power PCB layouts.
Technical Context
The LM2679SX-3.3/NOPB implements a fixed-frequency (260 kHz) current-mode PWM controller with internal DMOS high-side switch and bootstrap-driven gate circuitry. Its feedback loop senses output voltage directly at the FB pin (shorted to VOUT for fixed versions), enabling stable regulation without external divider resistors.
Current limiting is set by an external resistor (RADJ = 5.6 kΩ yields 6.3 A typical peak switch current), while soft-start is controlled by a capacitor on the SS pin that linearly ramps duty cycle. The device operates across –40°C to +125°C junction temperature and includes thermal shutdown and under-voltage lockout.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3 V ±2% 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 |
| Max Output Current | 5 A continuous - enabled by low RDS(ON) (0.14 Ω typ) DMOS switch |
| Switching Frequency | 260 kHz ±11% - enables use of compact off-the-shelf inductors and reduces EMI filtering burden |
| Efficiency | 82% typical at 12 VIN, 5 A - achieved via low-conduction-loss switch and optimized control architecture |
| Current Limit | 6.3 A typical (with 5.6 kΩ RADJ) - programmable from 3 A to 7 A for fault robustness tuning |
| Quiescent Current | 6 mA max - ensures low no-load power draw in always-on systems |
Pinout & Package
LM2679SX-3.3/NOPB is packaged in a 7-pin TO-263 (KTW) thermally enhanced surface-mount package (10.10 mm × 8.89 mm), with exposed DAP connected internally to GND for improved thermal dissipation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (SW) | Switch output | Drain node of internal DMOS FET; connects to inductor and Schottky diode cathode - high dv/dt switching node requiring tight layout |
| 2 (VIN) | Input supply | High-side switch source connection; must be decoupled with low-ESR CIN placed adjacent to pin - primary path for input ripple current |
| 3 (CB) | Bootstrap capacitor | Connects to SW via 0.01 µF ceramic capacitor; provides gate drive voltage > VIN to fully enhance DMOS switch |
| 4 (GND) | Power ground | Common return for input/output capacitors, current sense, and thermal pad - requires low-inductance plane connection |
| 5 (IADJ) | Current limit adjust | Inputs 1.21 V reference to set peak switch current via external resistor to GND (ICL = 37,125 / RADJ) |
| 6 (FB) | Feedback input | Direct connection to output for fixed 3.3-V version - internal resistor divider sets regulation point; no external components needed |
| 7 (SS) | Soft-start | Capacitor-to-GND sets ramp time for output voltage rise; prevents inrush current during startup - floating disables feature |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 120-mΩ DMOS switch | Enables 5-A output without external MOSFET; reduces BOM count and layout complexity vs. controller-only solutions |
| Resistor-programmable current limit | Allows precise tailoring of overcurrent protection threshold (3–7 A) without changing IC - simplifies design reuse across load variants |
| Fixed 260-kHz oscillator | Eliminates need for external timing components; ensures predictable EMI profile and simplifies filter design |
| ±2% output voltage tolerance | Meets tight regulation requirements for FPGA core rails and microprocessor I/O supplies without post-regulation |
| Thermal shutdown protection | Automatically disables switching above safe junction temperature - prevents damage during overload or poor heatsinking |
Applications
| Industrial PLC Power Rails | Telecom Line Card Pre-regulator |
|---|---|
Use Scenario: Providing stable 3.3-V bias for logic, communication interfaces, and analog front-ends in programmable logic controllers operating from 24-V DC bus. IC Role / Device Role / Timing Role: Primary buck regulator delivering regulated 3.3 V at up to 5 A; handles wide input transients and thermal cycling in cabinet-mounted enclosures. Use Value: ±2% output tolerance ensures reliable operation of sensitive digital ICs; TO-263 package enables direct heatsink mounting for convection-cooled designs. | Use Scenario: Generating 3.3-V intermediate rail from 48-V telecom supply to feed downstream point-of-load converters in base station line cards. IC Role / Device Role / Timing Role: High-efficiency preregulator stepping down 48 V to 3.3 V before final conversion; operates continuously under full load with minimal thermal derating. Use Value: 82% efficiency at 12-VIN/5-A reduces heat generation in dense card layouts; 260-kHz switching allows compact magnetics compatible with standard footprint constraints. |
| Battery-Powered Test Equipment | Automotive Aftermarket Infotainment |
Use Scenario: Converting 12–36-V Li-ion pack voltage to clean 3.3-V supply for embedded microcontrollers and ADCs in portable calibration tools. IC Role / Device Role / Timing Role: Main system regulator with soft-start to prevent battery voltage sag during power-up; withstands cold-crank and load-dump conditions via 40-V abs max rating. Use Value: Resistor-adjustable current limit protects battery cells during short-circuit faults; –40°C to 125°C operation supports extended field use. | Use Scenario: Powering USB hubs, display controllers, and audio codecs in vehicle infotainment head units supplied from 12-V automotive battery with wide transient range. IC Role / Device Role / Timing Role: Robust 3.3-V supply tolerant of 8–40-V input swings including jump-start surges and alternator ripple. Use Value: Integrated thermal shutdown prevents latch-up during prolonged high-ambient operation; TO-263 package offers superior thermal performance vs. TO-220 in confined dash spaces. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2678SX-3.3/NOPB | Same pinout, 3-A output rating, identical 260-kHz frequency and FB/SS/CB functions | Limited to 3-A loads; lower RDS(ON) (150 mΩ) increases conduction loss at 5 A | Select when load current ≤3 A and cost reduction is prioritized over headroom |
| TPS54560QDGQRQ1 | Adjustable output (0.8–60 V), 5-A, 100–2500-kHz sync capability, integrated compensation | Requires external feedback divider; higher quiescent current (125 µA vs. 6 mA); AEC-Q100 qualified | Choose for automotive-grade designs needing adjustable output or wider input range (3.5–60 V) |
Compared with LM2678SX-3.3/NOPB, the LM2679SX-3.3/NOPB delivers 66% higher current capacity with identical footprint and control interface; versus TPS54560QDGQRQ1, it offers simpler fixed-output implementation and lower IQ but lacks sync capability and automotive qualification.
Availability
LM2679SX-3.3/NOPB is available at Aetrix Electronics and suitable for industrial PLC power rails, telecom line card pre-regulators, and battery-powered test equipment requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LM2679SX-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 company headquartered in Dallas, Texas, specializing in analog, embedded processing, and power management technologies with broad industrial, automotive, and communications market reach.
The LM2679 series belongs to TI's SIMPLE SWITCHER® family of integrated DC/DC regulators, designed to simplify high-current buck converter implementation using minimal external components while maintaining high efficiency and reliability in harsh environments.
FAQ
What is the maximum input voltage rating for LM2679SX-3.3/NOPB?
The LM2679SX-3.3/NOPB has an absolute maximum input voltage rating of 45 V, with recommended operating range specified from 8 V to 40 V. Operation beyond 40 V risks exceeding safe operating area limits and may trigger internal protection circuits. This 40-V upper limit supports common industrial 24-V and 36-V bus systems, as well as automotive battery-derived supplies with transient spikes.
Does LM2679SX-3.3/NOPB require external feedback resistors?
No, LM2679SX-3.3/NOPB does not require external feedback resistors. As a fixed-output variant, it contains internal resistor dividers that set the regulated output to 3.3 V. The FB pin is internally connected to the output node, so only a direct trace from FB to VOUT is needed - eliminating component count, layout sensitivity, and tolerance drift associated with external dividers.
How is current limit configured on LM2679SX-3.3/NOPB?
Current limit on LM2679SX-3.3/NOPB is configured by connecting a single resistor (RADJ) between the IADJ pin (Pin 5) and GND. With RADJ = 5.6 kΩ, the typical peak switch current is 6.3 A. The relationship is defined as ICL = 37,125 / RADJ (in ohms), allowing adjustment from 3 A to 7 A. No additional components or configuration registers are required.
What package type is used for LM2679SX-3.3/NOPB?
LM2679SX-3.3/NOPB uses the TO-263-7 (KTW) package: a thermally enhanced surface-mount outline measuring 10.10 mm × 8.89 mm with an exposed thermal pad (DAP) tied internally to GND. This package provides superior thermal performance over TO-220 alternatives and supports high-current PCB layouts with direct heatsink attachment or copper pour for junction-to-board heat transfer.
Can LM2679SX-3.3/NOPB operate without a soft-start capacitor?
Yes, LM2679SX-3.3/NOPB can operate without a soft-start capacitor. The SS pin (Pin 7) may be left floating to disable soft-start functionality. When unconnected, the device starts immediately upon VIN application. Adding a capacitor (e.g., 1 nF) to GND introduces a controlled voltage ramp on the internal error amplifier, reducing inrush current - useful in battery-powered or low-input-capacitance systems.
LM2679SX-3.3/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):
- 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:
- TO-263 (DDPAK-7)
LM2679SX-3.3/NOPB FAQ
1.How can I place an order for LM2679SX-3.3/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2679SX-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 LM2679SX-3.3/NOPB reliable?
The price and inventory of LM2679SX-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 LM2679SX-3.3/NOPB is usually 5 days.
3.What payment methods are accepted for LM2679SX-3.3/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2679SX-3.3/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2679SX-3.3/NOPB?
LM2679SX-3.3/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2679SX-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 LM2679SX-3.3/NOPB?
For technical support, including LM2679SX-3.3/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2679SX-3.3/NOPB requirements.
6.How does Aetrix verify that LM2679SX-3.3/NOPB is sourced from the original manufacturer or authorized distributors?
All LM2679SX-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 LM2679SX-3.3/NOPB meets industry standards.
7.What is the process for return or replacement of LM2679SX-3.3/NOPB?
All LM2679SX-3.3/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM2679SX-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 LM2679SX-3.3/NOPB part is unused and in its original packaging.
Return procedure for LM2679SX-3.3/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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