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Texas Instruments LM2679SD-ADJ
- Part No.:
- LM2679SD-ADJ
- Manufacturer:
- Texas Instruments
- Package:
- 14-VDFN Exposed Pad
- Datasheet:
-
LM2679SD-ADJ.pdf
- Description:
- IC REG BUCK ADJ 5A 14VSON
- Quantity:
- Payment:
- Shipping:
Inventory:3,333
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Product details
Overview
LM2679SD-ADJ from Texas Instruments is a monolithic step-down (buck) DC-DC switching regulator IC with adjustable output voltage (1.2 V to 37 V), 5 A load capability, 260 kHz fixed-frequency PWM control, and resistor-programmable peak current limit (3 A to 7 A). It integrates a 120 mΩ DMOS power switch and supports industrial power conversion in battery chargers, pre-regulators for linear regulators, and embedded systems requiring high-efficiency mid-power conversion.
For engineers reviewing the LM2679SD-ADJ datasheet, LM2679SD-ADJ pinout, LM2679SD-ADJ application, or LM2679SD-ADJ equivalent, key selection criteria include input voltage range (8 V to 40 V), ±2% output tolerance over line/load, softstart programmability, thermal shutdown, and compatibility with standard off-the-shelf inductors and low-ESR output capacitors.
Technical Context
The LM2679SD-ADJ implements a fixed-frequency (225–280 kHz) current-mode PWM controller with internal 260 kHz oscillator, enabling stable regulation using external feedback resistors and a single current-limit programming resistor (RADJ). Its DMOS power switch features 0.12 Ω typical RDS(ON), minimizing conduction loss at 5 A continuous output.
Control architecture includes softstart via external capacitor (pin 7), boost capacitor (0.01 µF) for gate overdrive, and current-limit threshold set by RADJ = 37,125 / ICL. Feedback pin (pin 6) references 1.21 V typical, supporting precise output adjustment across 1.2 V–37 V range.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 8 V to 40 V - supports wide-range unregulated inputs including 12 V/24 V industrial rails and automotive battery-derived supplies. |
| Output Voltage Range | 1.2 V to 37 V - adjustable via external resistor divider on FB pin; enables flexible system-level voltage scaling. |
| Max Output Current | 5 A continuous - delivered with high efficiency (>84% at 12 VIN/5 VOUT) and thermal protection up to 125°C junction. |
| Oscillator Frequency | 260 kHz (±11%) - fixed internal clock enables predictable EMI profile and simplifies filter design with standard inductor values. |
| Current Limit Range | 3 A to 7 A - programmed via RADJ (e.g., 5.6 kΩ → 6.3 A typical); protects external components during overload or short-circuit. |
| Feedback Reference | 1.21 V (±2% over temp) - high-accuracy reference enables tight output regulation without trimming. |
| Thermal Shutdown | Active at TJ ≥ 160°C - automatically disables switch to prevent damage under sustained overload or poor heatsinking. |
Pinout & Package
LM2679SD-ADJ is packaged in a 14-pin VSON (NHM0014A) with exposed thermal pad (DAP), optimized for high-power density and thermal performance on PCBs with copper pour and thermal vias.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pin 2) | Power Input | Accepts 8–40 V supply; requires local 3×15 µF/50 V ceramic input capacitance for transient stability. |
| VSW (Pin 1 & 4) | Switch Node | Drives external inductor; swings from VIN to ~−0.5 V during OFF time; connects to CBOOST (0.01 µF). |
| GND (Pin 9) | Power Ground | Primary return path for switch current and IC bias; must connect directly to DAP and large ground plane. |
| CURRENT ADJ (Pin 5) | Current Limit Set | Connects to ground via RADJ; sets peak switch current as ICL = 37,125 / RADJ (Ω). |
| FB (Pin 6) | Feedback Input | Senses output voltage via resistor divider; internal 1.21 V reference defines VOUT = 1.21 × (1 + R1/R2). |
| SOFTSTART (Pin 7) | Startup Control | Accepts external capacitor to linearly ramp duty cycle; prevents input surge current at power-on. |
| DAP (Exposed Pad) | Thermal & Electrical Ground | Must be soldered to PCB ground plane with ≥12 thermal vias for θJA = 29°C/W performance. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 120 mΩ DMOS Switch | Enables 5 A output without external MOSFET; reduces BOM count and layout complexity in buck converters. |
| Resistor-Programmable Current Limit | Allows precise fault-current tailoring (3–7 A) to match inductor/diode ratings-reducing cost and size of external components. |
| 260 kHz Fixed-Frequency Operation | Ensures consistent EMI behavior and simplifies input/output filter design using industry-standard inductor families. |
| Softstart with External Capacitor | Eliminates output overshoot and inrush stress on input source; startup time programmable from milliseconds to seconds. |
| −40°C to +125°C Junction Range | Supports operation in harsh environments including industrial motor drives, battery-powered test equipment, and transportation electronics. |
Applications
| Battery Charger Interface | Industrial Pre-Regulator |
|---|---|
Use Scenario: Charging Li-ion or lead-acid batteries from variable 12–36 V DC sources (e.g., solar charge controllers or vehicle alternators). IC Role / Device Role / Timing Role: Primary step-down regulator delivering tightly regulated constant-voltage/constant-current output with programmable current limit to protect battery and charger circuitry. Use Value: Resistor-adjustable current limit (3–7 A) matches battery charge profiles; 8–40 V input accommodates wide-source fluctuations without dropout. | Use Scenario: Generating stable 3.3 V or 5 V intermediate rail from noisy 24 V factory bus for microcontrollers, sensors, and analog front-ends. IC Role / Device Role / Timing Role: High-efficiency pre-regulator preceding LDOs; handles bulk power conversion while rejecting input ripple and transients. Use Value: 92% peak efficiency minimizes heat in enclosed enclosures; ±2% output tolerance ensures reliable digital logic operation. |
| Embedded System Power Supply | Test & Measurement Equipment |
Use Scenario: Powering FPGA, DSP, or ARM-based modules in portable or rack-mounted instrumentation where board space and thermal management are constrained. IC Role / Device Role / Timing Role: Main DC-DC converter providing configurable output voltage (1.2–37 V) and robust overcurrent/thermal protection in compact VSON package. Use Value: VSON-14 with exposed DAP achieves 29°C/W θJA with proper PCB layout-enabling 5 A operation without heatsink in space-limited designs. | Use Scenario: Supplying precision analog circuitry (ADCs, DACs, op-amps) in benchtop analyzers or calibration tools requiring low-noise, stable voltage rails. IC Role / Device Role / Timing Role: Low-ripple, high-PSRR buck regulator feeding downstream LDOs; softstart prevents measurement disturbance during power-up. Use Value: 260 kHz switching frequency places fundamental noise outside sensitive audio/low-frequency bands; feedback accuracy (±2%) maintains reference stability. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2678SD-5.0 | Fixed 5 V output; no FB pin or external resistor divider; identical 5 A rating, 260 kHz, and package. | Not suitable for adjustable-output designs; eliminates need for feedback network but lacks flexibility. | Select when system requires only 5 V output and simplified BOM is prioritized over voltage configurability. |
| LM2596S-ADJ | 3 A max output; 150 kHz switching; 0.22 Ω RDS(ON); wider input range (4.5–40 V); different pinout and package (TO-263). | Lower current capacity and lower frequency increase inductor/capacitor size; less efficient at 5 A loads. | Choose for cost-sensitive, lower-power (<3 A) applications where thermal budget allows larger passive components. |
Compared with LM2678SD-5.0 and LM2596S-ADJ, the LM2679SD-ADJ uniquely balances 5 A capability, adjustable output, and 260 kHz operation in a thermally enhanced VSON package-making it optimal for mid-power industrial and embedded systems requiring design flexibility and thermal headroom.
Availability
LM2679SD-ADJ is available at Aetrix Electronics and suitable for battery chargers, industrial pre-regulators, and embedded system power supplies requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LM2679SD-ADJ 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 LM2679 series belongs to TI's SIMPLE SWITCHER® family-designed specifically for ease-of-use in non-isolated DC-DC buck applications, minimizing external component count while delivering up to 5 A with high efficiency and robust protection.
FAQ
What is the maximum input voltage rating for LM2679SD-ADJ?
The absolute maximum input voltage for LM2679SD-ADJ is 45 V, but the recommended operating range is 8 V to 40 V per the datasheet. Exceeding 40 V risks violating operating specifications and may trigger overvoltage stress on internal circuitry. For reliable long-term operation, maintain VIN ≤ 40 V with appropriate derating margin for transients.
How do I calculate the required RADJ resistor for a 4.5 A current limit on LM2679SD-ADJ?
Use the formula ICL = 37,125 / RADJ, rearranged as RADJ = 37,125 / ICL. For 4.5 A, RADJ = 37,125 / 4.5 ≈ 8.25 kΩ. A standard 8.25 kΩ ±1% metal-film resistor yields a typical current limit of 4.4 A, well within the 3–7 A programmable range supported by LM2679SD-ADJ.
Does LM2679SD-ADJ require a boost capacitor, and what value is recommended?
Yes, LM2679SD-ADJ requires a boost capacitor (CBOOST) connected between the BOOST pin (Pin 3) and VSW (Pin 1) to enhance gate drive voltage above VIN and fully turn on the internal DMOS switch. The datasheet specifies 0.01 µF (10 nF), 50 V ceramic capacitor as mandatory for achieving specified RDS(ON) and efficiency-omitting it degrades switching performance and increases conduction loss.
What thermal management is required for LM2679SD-ADJ at full 5 A load?
At 5 A continuous load, LM2679SD-ADJ in VSON-14 package requires PCB-level thermal design: the exposed DAP must be soldered to a minimum 1.0064 in² copper area with ≥12 thermal vias to an inner ground plane. This achieves θJA = 29°C/W, limiting junction temperature rise to ~145°C at 25°C ambient-within the −40°C to +125°C operating range when combined with thermal shutdown.
Can LM2679SD-ADJ be used in discontinuous conduction mode (DCM)?
Yes, LM2679SD-ADJ operates in both continuous (CCM) and discontinuous (DCM) conduction modes depending on load, inductance, and input/output voltage. DCM occurs naturally below ~1 A load at typical settings; the device maintains regulation and exhibits characteristic ringing-free waveforms per Figure 13 of the SNVS026N datasheet-no mode-control pins or external circuitry are needed.
LM2679SD-ADJ 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:
- 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:
- 14-VSON (5x6)
LM2679SD-ADJ FAQ
1.How can I place an order for LM2679SD-ADJ through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2679SD-ADJ 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 LM2679SD-ADJ reliable?
The price and inventory of LM2679SD-ADJ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2679SD-ADJ is usually 5 days.
3.What payment methods are accepted for LM2679SD-ADJ?
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Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2679SD-ADJ?
LM2679SD-ADJ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2679SD-ADJ 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 LM2679SD-ADJ?
For technical support, including LM2679SD-ADJ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2679SD-ADJ requirements.
6.How does Aetrix verify that LM2679SD-ADJ is sourced from the original manufacturer or authorized distributors?
All LM2679SD-ADJ 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 LM2679SD-ADJ meets industry standards.
7.What is the process for return or replacement of LM2679SD-ADJ?
All LM2679SD-ADJ units undergo pre-shipment inspection (PSI). If there is an issue with LM2679SD-ADJ, 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 LM2679SD-ADJ part is unused and in its original packaging.
Return procedure for LM2679SD-ADJ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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