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Texas Instruments LM2679SDX-3.3
- Part No.:
- LM2679SDX-3.3
- Manufacturer:
- Texas Instruments
- Package:
- 14-VDFN Exposed Pad
- Datasheet:
-
LM2679SDX-3.3.pdf
- Description:
- IC REG BUCK 3.3V 5A 14VSON
- Quantity:
- Payment:
- Shipping:
Inventory:1,252
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Product details
Overview
LM2679SDX-3.3 from Texas Instruments is a monolithic 5A step-down (buck) DC/DC voltage regulator with fixed 3.3V output, 260 kHz fixed-frequency internal oscillator, 120 mΩ DMOS output switch, and resistor-programmable current limit (3A–7A). It operates from 8V to 40V input and delivers ±2% output tolerance over full line/load/temperature range, used in industrial power supplies and embedded system pre-regulators.
For engineers reviewing the LM2679SDX-3.3 datasheet, LM2679SDX-3.3 pinout, LM2679SDX-3.3 application, or LM2679SDX-3.3 equivalent, key selection criteria include input voltage range (8–40V), peak switch current programmability via RADJ, thermal performance in DDPAK package, softstart timing control, and compatibility with standard off-the-shelf inductors and low-ESR output capacitors.
Technical Context
The LM2679SDX-3.3 integrates a PWM controller, 120 mΩ DMOS power switch, and internal feedback amplifier with 1.21V reference for fixed 3.3V regulation. Its 260 kHz oscillator enables predictable external component sizing and stable loop compensation without external frequency setting.
Current limiting is implemented via an external resistor (RADJ) connected between CURRENT ADJ pin and ground, establishing ICL = 37,125 / RADJ (e.g., 5.6 kΩ → 6.3 A typical). Softstart is controlled by a capacitor on the SOFTSTART pin, linearly ramping duty cycle to suppress inrush current.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3 V ±2% over −40°C to +125°C, 8V–40V input, 100 mA–5 A load |
| Switching Frequency | 260 kHz fixed (±11%), enabling consistent inductor/capacitor selection and EMI predictability |
| Peak Switch Current Limit | Resistor-programmable from 3 A to 7 A via RADJ; 5.6 kΩ sets ~6.3 A typical |
| DMOS RDS(ON) | 0.12 Ω typical at 5 A, minimizing conduction loss and supporting >90% efficiency |
| Input Voltage Range | 8 V to 40 V DC, with 45 V absolute maximum rating for transient robustness |
| Efficiency | Up to 92% (at 12 VIN, 5 A load for LM2679-12); LM2679SDX-3.3 achieves ≥82% at 12 VIN/5 A |
| Junction Temperature Range | −40°C to +125°C, validated for industrial and automotive under-hood environments |
Pinout & Package
LM2679SDX-3.3 is housed in a thermally enhanced 7-lead DDPAK (KTW) package (Package Number KTW0007B), with exposed die attach pad (DAP) designed for direct PCB ground connection to optimize thermal resistance (θJA = 26°C/W with 7.4× copper area).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VSW | Switch Node Output | Drives external inductor; swings from VIN to ~−0.5 V during OFF time; requires low-inductance Schottky catch diode path |
| VIN | Main Power Input | Accepts 8–40 V DC; must be bypassed with ≥3×15 μF/50 V ceramic+electrolytic input capacitance near pin |
| CBOOST | Bootstrap Capacitor Terminal | Connects to VSW; 0.01 μF/50 V ceramic required to gate-drive DMOS switch above VIN for low RDS(ON) |
| GND | Power & Signal Ground | Common return for all circuits; requires low-impedance ground plane due to high di/dt switching currents |
| CURRENT ADJ | Current Limit Programming | Connects to ground via RADJ (e.g., 5.6 kΩ) to set peak switch current per ICL = 37,125/RADJ |
| FB | Feedback Input | Internally tied to 3.3 V divider; no external resistors needed - direct output connection provides regulation |
| SOFTSTART | Softstart Timing Control | Capacitor to ground (e.g., 1 nF) linearly ramps duty cycle at startup to limit input surge current |
Key Features
| Feature | Design Value |
|---|---|
| Resistor-programmable current limit | Enables precise fault-current tailoring (3–7 A) using single RADJ resistor - avoids oversized magnetics and diodes |
| Integrated 120 mΩ DMOS switch | Eliminates external MOSFET and driver; reduces BOM count and layout complexity while maintaining >90% efficiency |
| 260 kHz fixed-frequency operation | Ensures consistent EMI profile and simplifies filter design; supports use of standardized off-the-shelf inductors |
| Softstart with external capacitor | Prevents input surge and output overshoot during power-up; timing fully adjustable without changing IC or layout |
| Thermal shutdown protection | Automatically disables switching if junction temperature exceeds safe limit - protects IC and downstream circuitry |
Applications
| Industrial PLC Power Rails | Embedded System Pre-Regulator |
|---|---|
Use Scenario: Providing clean, regulated 3.3 V rail for microcontrollers, FPGAs, and communication peripherals in programmable logic controllers operating from 24 V DC bus. IC Role / Device Role / Timing Role: Primary buck regulator delivering up to 5 A continuous current with tight output tolerance and thermal resilience. Use Value: Eliminates need for discrete MOSFET + controller design; maintains ±2% output accuracy across −40°C to +85°C ambient with minimal external components. | Use Scenario: Generating stable 3.3 V supply for ARM-based SBCs and IoT gateways powered from wide-range 12–36 V industrial inputs. IC Role / Device Role / Timing Role: High-efficiency pre-regulator stepping down unregulated input before LDO post-regulation for noise-sensitive analog sections. Use Value: Achieves ≥82% efficiency at full 5 A load, reducing heat sink requirements and enabling compact board layouts in space-constrained enclosures. |
| Battery Charger Auxiliary Supply | Test Equipment Power Module |
Use Scenario: Powering control circuitry and display drivers in multi-cell lithium-ion battery chargers where input varies from 10 V (partially discharged) to 40 V (boosted bus). IC Role / Device Role / Timing Role: Robust main DC/DC converter handling wide input transients and load steps during charge algorithm transitions. Use Value: Resistor-programmable current limit allows safe operation into short-circuit faults without latch-off, supporting reliable charger safety compliance. | Use Scenario: Delivering calibrated 3.3 V power to precision ADCs, DACs, and reference buffers in benchtop test instruments requiring low-noise, stable supply rails. IC Role / Device Role / Timing Role: Fixed-output buck regulator with low output ripple (<1% VOUT) enabled by optimized COUT selection and internal compensation. Use Value: Maintains ±2% output tolerance over full temperature and load range - critical for measurement accuracy in metrology-grade equipment. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2678SDX-3.3 | Same pinout, 260 kHz, but lacks adjustable current limit; fixed 7 A limit and no CURRENT ADJ pin | Suitable only where programmable fault current is unnecessary; less flexible for current-limited designs | Choose when cost reduction is prioritized over current-limit flexibility and thermal optimization |
| TPS54560DGQ | 4.5–60 V input, 5 A, 2.5 MHz switching, integrated compensation; different pinout and control architecture | Supports higher input voltages and faster transient response; requires redesign of layout and compensation network | Prefer for new designs needing wider VIN range, smaller magnetics, or tighter dynamic regulation |
Compared with LM2678SDX-3.3 and TPS54560DGQ, the LM2679SDX-3.3 uniquely balances wide-input capability (8–40 V), programmable current limiting, and proven thermal performance in DDPAK - making it optimal for industrial systems requiring field-replaceable fault resilience without layout rework.
Availability
LM2679SDX-3.3 is available at Aetrix Electronics and suitable for industrial PLCs, embedded pre-regulators, battery charger auxiliary supplies, and test equipment power modules requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LM2679SDX-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 ICs, with decades of expertise in high-reliability power conversion solutions.
The LM2679 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, predictable performance, and rugged operation are essential.
FAQ
What is the maximum input voltage rating for LM2679SDX-3.3?
The LM2679SDX-3.3 has an absolute maximum input voltage rating of 45 V, with recommended operating range of 8 V to 40 V DC. Exceeding 40 V continuously may reduce reliability or trigger overvoltage protection in upstream circuitry; transient spikes up to 45 V are tolerated per datasheet limits.
Does LM2679SDX-3.3 require external feedback resistors?
No - the LM2679SDX-3.3 is a fixed 3.3 V output variant. Its internal feedback divider is factory-trimmed; the FB pin connects directly to the output node with no external resistors required. This simplifies layout and improves regulation accuracy versus adjustable versions.
How is current limit set on LM2679SDX-3.3?
Current limit on LM2679SDX-3.3 is set by connecting a resistor (RADJ) between the CURRENT ADJ pin and ground. The peak switch current follows ICL = 37,125 / RADJ; for example, 5.6 kΩ yields ~6.3 A typical. This enables precise fault-current tailoring without changing the LM2679SDX-3.3 itself.
What package type does LM2679SDX-3.3 use, and how should the DAP be handled?
The LM2679SDX-3.3 uses the 7-lead DDPAK (KTW) package with exposed die attach pad (DAP). Per TI AN-1187, the DAP must be soldered to a large PCB ground copper area - ideally with ≥12 thermal vias to an inner ground plane - to achieve θJA = 26°C/W and prevent thermal shutdown under 5 A load.
Can LM2679SDX-3.3 operate without a softstart capacitor?
Yes - the SOFTSTART pin of LM2679SDX-3.3 may be left open-circuited if softstart is not required. However, omitting the capacitor increases inrush current and risks output overshoot during startup, especially under light-load conditions; TI recommends 1 nF for general-purpose softstart timing.
LM2679SDX-3.3 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- SIMPLE SWITCHER®
- Package/Case:
- 14-VDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- 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:
- Surface Mount
- Supplier Device Package:
- 14-VSON (5x6)
LM2679SDX-3.3 FAQ
1.How can I place an order for LM2679SDX-3.3 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2679SDX-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 LM2679SDX-3.3 reliable?
The price and inventory of LM2679SDX-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 LM2679SDX-3.3 is usually 5 days.
3.What payment methods are accepted for LM2679SDX-3.3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2679SDX-3.3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2679SDX-3.3?
LM2679SDX-3.3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2679SDX-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 LM2679SDX-3.3?
For technical support, including LM2679SDX-3.3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2679SDX-3.3 requirements.
6.How does Aetrix verify that LM2679SDX-3.3 is sourced from the original manufacturer or authorized distributors?
All LM2679SDX-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 LM2679SDX-3.3 meets industry standards.
7.What is the process for return or replacement of LM2679SDX-3.3?
All LM2679SDX-3.3 units undergo pre-shipment inspection (PSI). If there is an issue with LM2679SDX-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 LM2679SDX-3.3 part is unused and in its original packaging.
Return procedure for LM2679SDX-3.3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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