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Texas Instruments LM2679SDX-ADJ/NOPB
- Part No.:
- LM2679SDX-ADJ/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- 14-VDFN Exposed Pad
- Datasheet:
-
LM2679SDX-ADJ/NOPB.pdf
- Description:
- IC REG BUCK ADJ 5A 14VSON
- Quantity:
- Payment:
- Shipping:
Inventory:3,915
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Product details
Overview
LM2679SDX-ADJ/NOPB from Texas Instruments is a monolithic 5-A step-down (buck) DC/DC voltage regulator with adjustable output (1.2 V to 37 V), 260-kHz fixed-frequency PWM control, 120-mΩ DMOS high-side switch, and resistor-programmable current limit (5.5–7.6 A at 25°C). It operates from 8 V to 40 V input and delivers ±2% output voltage accuracy across line, load, and temperature - used in industrial power supplies and battery chargers.
For engineers reviewing the LM2679SDX-ADJ/NOPB datasheet, LM2679SDX-ADJ/NOPB pinout, LM2679SDX-ADJ/NOPB application, or LM2679SDX-ADJ/NOPB equivalent, key selection criteria include its adjustable feedback architecture, soft-start timing capacitor interface, bootstrapped gate drive (CB pin), thermal shutdown protection, and compatibility with standard off-the-shelf inductors and low-ESR output capacitors.
Technical Context
The LM2679SDX-ADJ/NOPB implements a voltage-mode PWM controller with a fixed 260-kHz oscillator driving an integrated 120-mΩ DMOS high-side switch. Its feedback loop senses output voltage via an external resistor divider connected to the FB pin, referencing a precise 1.21-V internal bandgap (±1.2% over –40°C to 125°C).
Current limiting is set by a resistor (RADJ) from the Current_adjust pin to GND, establishing ICL = 37,125 / RADJ (e.g., 5.6 kΩ yields 6.3 A typical). Soft-start is controlled by a capacitor on the SS pin, while the CB pin enables bootstrap gate drive for full enhancement of the internal MOSFET.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output current | 5 A continuous - supports high-power loads without external current-sharing circuitry |
| Input voltage range | 8 V to 40 V - compatible with 12 V/24 V industrial rails and wide-range unregulated supplies |
| Output voltage range | 1.2 V to 37 V adjustable - configured via external resistor divider on FB pin |
| Switch RDS(ON) | 0.14 Ω max at 25°C - minimizes conduction loss and enables >92% peak efficiency |
| Oscillator frequency | 260 kHz ±11% - enables use of compact, standardized inductors and reduces EMI compared to higher frequencies |
| Feedback reference | 1.21 V ±1.2% - sets output accuracy; tolerance directly impacts final VOUT stability under varying conditions |
| Current limit range | 5.5 A to 7.6 A (at 25°C) - programmable via RADJ to match load fault thresholds and PCB trace capability |
Pinout & Package
LM2679SDX-ADJ/NOPB is packaged in a 7-pin TO-263 (KTW) surface-mount package with exposed thermal pad (10.10 mm × 8.89 mm), optimized for high-current thermal dissipation on PCB copper planes.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (Switch_output) | High-side MOSFET drain node | Switching node connecting to inductor and Schottky diode cathode; requires low-inductance layout to minimize ringing |
| 2 (Input) | Main power input | Connects to VIN (8–40 V) and high-frequency input bypass capacitors; shortest possible path to GND critical |
| 3 (CB) | Bootstrap capacitor connection | Accepts 0.01 µF ceramic capacitor to VSW (pin 1); enables full gate drive above VIN for low RDS(ON) |
| 4 (GND) | Power ground | Common return for input/output capacitors, thermal pad, and internal circuitry; must tie to large copper area |
| 5 (Current_adjust) | Peak current limit programming | Accepts resistor to GND; sets ICL = 37,125 / RADJ (e.g., 5.6 kΩ → ~6.3 A); determines short-circuit response |
| 6 (FB) | Feedback voltage sense | Monitors output via resistor divider; regulates VOUT to 1.21 V reference; high-impedance (85 nA bias current) |
| 7 (SS) | Soft-start timing input | Accepts capacitor to GND; controls output ramp rate and limits inrush current during startup |
Key Features
| Feature | Design Value |
|---|---|
| Resistor-programmable current limit | Enables precise matching of overcurrent threshold to system-level fault requirements without redesigning PCB layout |
| Integrated 120-mΩ DMOS switch | Eliminates need for external high-current MOSFET and driver, reducing BOM count and layout complexity |
| 260-kHz fixed-frequency operation | Allows predictable EMI filtering and simplifies inductor selection using TI-recommended standard parts |
| Soft-start with external capacitor | Prevents input surge current and output overshoot during power-up, improving reliability in multi-rail systems |
| Thermal shutdown protection | Automatically disables switching if junction temperature exceeds safe operating limit, preventing permanent damage |
Applications
| Industrial Power Supply | Battery Charger |
|---|---|
|
Use Scenario: 24-V input converted to 13.8-V/5-A for lead-acid battery float charging in telecom backup systems. IC Role / Device Role / Timing Role: Primary buck regulator providing constant-voltage/constant-current regulation with programmable current limit for charge termination. Use Value: Resistor-adjustable current limit (via RADJ) allows precise tailoring to battery chemistry without component changes. |
Use Scenario: 36-V nominal lithium-ion pack charged from 40-V vehicle supply in EV auxiliary systems. IC Role / Device Role / Timing Role: Pre-regulator stepping down variable input to stable intermediate bus for linear charger ICs. Use Value: Wide 8–40 V input range accommodates automotive transients; ±2% output tolerance ensures accurate cell voltage control. |
| Programmable Lab PSU | Motor Drive Power Stage |
|
Use Scenario: Bench power supply with digitally controlled output (1.2–30 V) and current limiting for prototyping. IC Role / Device Role / Timing Role: Adjustable-output buck stage delivering clean, regulated DC with user-set voltage/current limits. Use Value: FB pin interface enables precision DAC-based voltage setting; SS pin supports smooth output ramping during setpoint changes. |
Use Scenario: 24-V supply powering logic and gate drivers in a 5-A brushed DC motor controller. IC Role / Device Role / Timing Role: Point-of-load regulator generating stable 5-V rail for microcontroller and driver ICs. Use Value: Integrated thermal shutdown protects against motor stall-induced overload; TO-263 package enables direct heatsinking to chassis. |
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-5.0/NOPB | Fixed 5-V output; no FB or RADJ pins; identical package and 5-A rating | Lacks output adjustability and current limit programming - suitable only where 5 V is sufficient | Select when design requires fixed 5-V output and simplified feedback network; not interchangeable with LM2679SDX-ADJ/NOPB |
| TPS54560DGQR | 60-V input, 5-A synchronous buck; 100-kHz–2.5-MHz adjustable frequency; no external current sense resistor needed | Higher input voltage range and integrated high-/low-side FETs reduce external component count but require different compensation | Choose for wider VIN (6–60 V) or where synchronous rectification improves light-load efficiency; layout and loop compensation differ significantly |
Compared with LM2678SDX-5.0/NOPB, LM2679SDX-ADJ/NOPB provides output flexibility and fault-current tuning at the cost of two extra external resistors; versus TPS54560DGQR, it offers simpler design and proven thermal robustness in 8–40 V industrial environments but lacks frequency agility and synchronous efficiency.
Availability
LM2679SDX-ADJ/NOPB is available at Aetrix Electronics and suitable for industrial power supplies, battery chargers, and programmable lab power supplies requiring stable component supply, long-term lifecycle support, and consistent parametric performance across temperature and load.
Supply support for LM2679SDX-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 company headquartered in Dallas, Texas, specializing in analog, embedded processing, and power management technologies with broad industrial and automotive design-in leadership.
The LM2679 series belongs to TI's SIMPLE SWITCHER® family - designed specifically for ease-of-use in non-isolated DC/DC buck conversion, emphasizing minimal external components, thermal resilience, and compatibility with standard magnetics.
FAQ
What is the maximum output voltage achievable with LM2679SDX-ADJ/NOPB?
The LM2679SDX-ADJ/NOPB supports an adjustable output range from 1.2 V to 37 V, determined by the external resistor divider on the FB pin. This upper limit is constrained by internal voltage ratings and stability margins - exceeding 37 V risks violating absolute maximum ratings on the FB pin and may compromise loop stability or regulation accuracy. Always verify operation within the recommended 8–40 V input range when targeting high outputs.
How do I calculate the current limit resistor (RADJ) for LM2679SDX-ADJ/NOPB?
For LM2679SDX-ADJ/NOPB, the peak switch current limit is calculated as ICL = 37,125 / RADJ, where RADJ is in ohms and ICL is in amperes. For example, a 5.6-kΩ resistor yields ~6.6 A typical limit. The datasheet specifies ICL = 5.5–7.6 A at 25°C with this value. Ensure RADJ tolerance (1% preferred) and temperature coefficient align with required fault-current margin across operating temperature.
Can LM2679SDX-ADJ/NOPB operate without the bootstrap capacitor (CB pin)?
No - LM2679SDX-ADJ/NOPB requires a 0.01-µF ceramic capacitor between the CB pin and the Switch_output (pin 1) to enable proper gate drive of the internal DMOS switch. Omitting this capacitor prevents full enhancement of the high-side FET, causing excessive conduction loss, thermal runaway, and potential device failure. TI specifies X7R or C0G dielectric with low ESR for reliable bootstrap operation.
What is the purpose of the SS (soft-start) pin on LM2679SDX-ADJ/NOPB?
The SS pin on LM2679SDX-ADJ/NOPB controls the output voltage ramp rate during startup by integrating an internal current source into an external capacitor. A typical 1-nF capacitor yields ~10-ms soft-start time, limiting inrush current and preventing output overshoot. Leaving SS floating disables soft-start; tying it to GND forces immediate startup but removes surge protection - both configurations are valid depending on system requirements.
Does LM2679SDX-ADJ/NOPB require external compensation components?
No - LM2679SDX-ADJ/NOPB features internal frequency compensation optimized for standard external component values (e.g., 10–47 µH inductors, 100–470 µF output capacitors). TI's application notes confirm stable operation with recommended parts without adding external RC networks. However, significant deviations in L, COUT, or ESR may necessitate re-evaluation per Section 8.1.3 of the datasheet.
LM2679SDX-ADJ/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- SIMPLE SWITCHER®
- Package/Case:
- 14-VDFN Exposed Pad
- 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:
- 14-VSON (5x6)
LM2679SDX-ADJ/NOPB FAQ
1.How can I place an order for LM2679SDX-ADJ/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2679SDX-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 LM2679SDX-ADJ/NOPB reliable?
The price and inventory of LM2679SDX-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 LM2679SDX-ADJ/NOPB is usually 5 days.
3.What payment methods are accepted for LM2679SDX-ADJ/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2679SDX-ADJ/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2679SDX-ADJ/NOPB?
LM2679SDX-ADJ/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2679SDX-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 LM2679SDX-ADJ/NOPB?
For technical support, including LM2679SDX-ADJ/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2679SDX-ADJ/NOPB requirements.
6.How does Aetrix verify that LM2679SDX-ADJ/NOPB is sourced from the original manufacturer or authorized distributors?
All LM2679SDX-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 LM2679SDX-ADJ/NOPB meets industry standards.
7.What is the process for return or replacement of LM2679SDX-ADJ/NOPB?
All LM2679SDX-ADJ/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM2679SDX-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 LM2679SDX-ADJ/NOPB part is unused and in its original packaging.
Return procedure for LM2679SDX-ADJ/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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