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Texas Instruments LM2679SX-ADJ/NOPB
- Part No.:
- LM2679SX-ADJ/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- TO-263-8, D2PAK (7 Leads + Tab), TO-263CA
- Datasheet:
-
LM2679SX-ADJ/NOPB.pdf
- Description:
- IC REG BUCK ADJ 5A TO263
- Quantity:
- Payment:
- Shipping:
Inventory:1,922
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Product details
Overview
LM2679SX-ADJ/NOPB from Texas Instruments is a monolithic 5-A step-down (buck) DC/DC regulator with adjustable output voltage (1.2 V to 37 V), 260-kHz fixed-frequency PWM control, and resistor-programmable current limit (5.5 A typical at RADJ = 5.6 kΩ). It integrates a 120-mΩ DMOS high-side switch and supports industrial power conversion in battery chargers, system preregulators, and distributed supply rails.
For engineers reviewing the LM2679SX-ADJ/NOPB datasheet, LM2679SX-ADJ/NOPB pinout, LM2679SX-ADJ/NOPB application, or LM2679SX-ADJ/NOPB equivalent, key selection criteria include input voltage range (8 V–40 V), ±2% output voltage tolerance, soft-start timing via external capacitor, thermal shutdown protection, and compatibility with standard off-the-shelf inductors and low-ESR output capacitors.
Technical Context
The LM2679SX-ADJ/NOPB implements a voltage-mode PWM controller with internal 260-kHz oscillator and two-stage feedback amplifier referenced to 1.21 V nominal VFB. Its DMOS power switch operates with 120-mΩ RDS(ON) at TJ = 25°C, enabling >92% peak efficiency at 12-V input and 5-A load. Current limiting is set by external resistor RADJ using ICL = 37,125 / RADJ (A), with factory-trimmed VADJ = 1.21 V.
Soft-start is implemented via external capacitor on SS pin, generating controlled duty-cycle ramp-up; bootstrapping is handled by CB pin connected to VSW through 0.01-μF capacitor. The device requires no external compensation and maintains stability with standard ceramic or tantalum output capacitors meeting ESR and capacitance targets per TI design guidelines.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output current | 5 A continuous; supports full-load operation without derating under recommended PCB copper area and ambient conditions |
| Input voltage range | 8 V to 40 V DC; enables direct use with 12-V, 24-V, and 36-V industrial or automotive battery systems |
| Output voltage range | 1.2 V to 37 V adjustable via external resistor divider; FB pin reference is 1.21 V ±1.2% over temperature |
| Switching frequency | 260 kHz fixed; allows predictable EMI filtering and use of compact, standardized inductor families |
| Current limit accuracy | ±12% over –40°C to 125°C; set by RADJ with ICL = 37,125 / RADJ (e.g., 5.6 kΩ → 6.3 A typ) |
| Efficiency | Up to 92% at VIN = 24 V, VOUT = 12 V, IOUT = 5 A; enabled by low RDS(ON) DMOS switch and optimized gate drive |
| Thermal shutdown | Active at TJ ≥ 160°C; hysteresis ensures safe restart after cooldown without external circuitry |
Pinout & Package
LM2679SX-ADJ/NOPB is packaged in TO-263 (KTW) - a 7-pin surface-mount DDPAK with exposed thermal pad (DAP), 10.10 mm × 8.89 mm body size, and integrated heat dissipation path to PCB copper.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (SW) | Switch output | Drain node of internal DMOS FET; connects to inductor and Schottky diode cathode; switches between VIN and ~−0.5 V during OFF state |
| 2 (VIN) | Input supply | Main power input (8–40 V); supplies both load energy and internal bias; requires low-impedance connection to CIN |
| 3 (CB) | Bootstrap capacitor | Connects to SW via 0.01-μF capacitor; provides gate-drive voltage > VIN for full enhancement of high-side FET |
| 4 (GND) | Power ground | Common return for input/output capacitors, feedback network, and thermal pad; must be low-inductance plane |
| 5 (IADJ) | Current limit adjust | Accepts resistor to GND; sets peak switch current via ICL = 37,125 / RADJ (A); 5.6 kΩ yields 6.3 A typical |
| 6 (FB) | Feedback sense | High-impedance input (85 nA bias) referenced to 1.21 V; connects to resistor divider for adjustable output or directly to VOUT for fixed versions |
| 7 (SS) | Soft-start | Accepts external capacitor to GND; controls output voltage ramp rate; floating disables soft-start |
Key Features
| Feature | Design Value |
|---|---|
| Resistor-programmable current limit | Enables precise fault-current tailoring (3 A–7 A range) without redesigning magnetics or layout; eliminates oversized external components |
| Integrated 120-mΩ DMOS switch | Reduces conduction losses and external component count; eliminates need for discrete high-current MOSFET and driver |
| Fixed 260-kHz oscillator | Ensures consistent EMI profile and simplifies filter design; avoids variable-frequency jitter and loop-compensation complexity |
| ±2% output voltage tolerance | Maintains regulation accuracy across line, load, and temperature without post-production trimming or calibration |
| Internal thermal shutdown | Protects IC and system during overload or poor heatsinking; auto-recovery prevents latch-up and manual reset |
Applications
| Battery Charging System | Industrial Preregulator |
|---|---|
Use Scenario: Constant-current/constant-voltage charging of 12-V lead-acid or LiFePO₄ battery packs from unregulated 24-V bus. IC Role / Device Role / Timing Role: Primary buck regulator delivering regulated 14.4-V output with programmable 5-A charge current and thermal foldback. Use Value: Resistor-adjustable current limit matches battery chemistry requirements; soft-start prevents inrush into large battery capacitance. | Use Scenario: Pre-regulating 36-V industrial rail down to 12-V before linear LDO stage for noise-sensitive analog subsystems. IC Role / Device Role / Timing Role: High-efficiency intermediate converter reducing power dissipation in downstream LDOs. Use Value: 92% efficiency at 24-V input/12-V output minimizes thermal load; fixed 260-kHz switching enables predictable EMI filtering. |
| Distributed Power Supply | Embedded Control Module |
Use Scenario: Generating 5-V/5-A local supply for FPGA, microcontroller, and peripheral logic in programmable logic controllers (PLCs). IC Role / Device Role / Timing Role: Main DC/DC converter powering digital core and I/O banks with tight transient response. Use Value: Fast load-transient recovery (<100 μs) and ±2% output tolerance ensure stable digital operation under dynamic load steps. | Use Scenario: Powering isolated sensor interface and CAN transceiver in automotive body control module with 12-V battery input. IC Role / Device Role / Timing Role: Robust primary regulator supporting wide-input (8–40 V) operation including cold-crank and load-dump conditions. Use Value: 40-V absolute max input rating and thermal shutdown protect against automotive transients; TO-263 package enables reliable thermal coupling to chassis ground. |
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/NOPB | Fixed 5-V output; identical pinout, package, and current capability; lacks adjustable feedback and current-limit programming | Suitable only where 5-V output is fixed and no current-limit tuning is needed | Select when output voltage is invariant and board space permits removal of feedback resistors |
| LM5164QDDARQ1 | 42-V input, 1-A output, 1-MHz switching, integrated high-side FET; AEC-Q100 qualified; different pinout and control architecture | Designed for automotive infotainment and ADAS; not drop-in compatible due to lower current and higher frequency | Choose for automotive safety-critical systems requiring qualification and higher switching frequency |
Compared with LM2678SD-5.0/NOPB, LM2679SX-ADJ/NOPB adds output voltage flexibility and current-limit tuning at the cost of two external resistors; versus LM5164QDDARQ1, it delivers 5× higher output current but lacks automotive qualification and operates at lower frequency for simpler EMI management.
Availability
LM2679SX-ADJ/NOPB is available at Aetrix Electronics and suitable for battery charging systems, industrial preregulators, and distributed power supplies requiring stable component supply, long-term manufacturability, and proven thermal performance in TO-263 packages.
Supply support for LM2679SX-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, designing and manufacturing analog, embedded processing, and power management ICs for industrial, automotive, and communications markets.
The LM2679 series belongs to TI's SIMPLE SWITCHER® power converter family, engineered for rapid, reliable buck regulator implementation using minimal external components and industry-standard magnetics.
FAQ
What is the maximum input voltage rating for LM2679SX-ADJ/NOPB?
The LM2679SX-ADJ/NOPB has an absolute maximum input voltage rating of 45 V, with recommended operating range from 8 V to 40 V DC. Operation above 40 V is not advised for sustained use, as electrical characteristics are specified only up to 40 V, and exceeding this may impact reliability or trigger overvoltage protection mechanisms not explicitly documented in the datasheet.
How do I set the output voltage of LM2679SX-ADJ/NOPB to 15 V?
To set LM2679SX-ADJ/NOPB output to 15 V, connect a resistor divider from VOUT to FB (pin 6) and FB to GND. With VFB = 1.21 V nominal, use R1 = 11.4 kΩ (top) and R2 = 1.0 kΩ (bottom) for 15 V: VOUT = 1.21 × (1 + R1/R2). Ensure R2 draws ≥10× FB bias current (85 nA) and place divider close to FB pin to minimize noise pickup.
What is the purpose of the CB pin on LM2679SX-ADJ/NOPB?
The CB (bootstrap capacitor) pin on LM2679SX-ADJ/NOPB connects to the SW node via a 0.01-μF capacitor to generate a gate-drive voltage above VIN for the internal high-side DMOS FET. This ensures full enhancement of the switch, minimizing RDS(ON) and conduction losses. Incorrect CB capacitor value or placement causes erratic switching or thermal shutdown.
Can LM2679SX-ADJ/NOPB operate without a soft-start capacitor?
Yes, LM2679SX-ADJ/NOPB can operate with SS pin left floating, which disables soft-start. However, omitting the soft-start capacitor may cause high inrush current during startup, potentially tripping upstream current limits or causing output overshoot. TI recommends a 1-nF capacitor for typical applications unless fast turn-on is explicitly required.
What thermal performance can be expected from LM2679SX-ADJ/NOPB in TO-263 package?
In the TO-263 (KTW) package, LM2679SX-ADJ/NOPB achieves RθJA = 26°C/W with 7.4× paddle-area copper and 12 vias to inner layers, and 35°C/W with 3.6× paddle-area copper. At 5-A load and 12-V input, junction temperature rise is ~130°C above ambient under worst-case 35°C/W condition-requiring adequate PCB copper and airflow to stay within –40°C to 125°C operating range.
LM2679SX-ADJ/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:
- 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:
- TO-263 (DDPAK-7)
LM2679SX-ADJ/NOPB FAQ
1.How can I place an order for LM2679SX-ADJ/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2679SX-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 LM2679SX-ADJ/NOPB reliable?
The price and inventory of LM2679SX-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 LM2679SX-ADJ/NOPB is usually 5 days.
3.What payment methods are accepted for LM2679SX-ADJ/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2679SX-ADJ/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2679SX-ADJ/NOPB?
LM2679SX-ADJ/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2679SX-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 LM2679SX-ADJ/NOPB?
For technical support, including LM2679SX-ADJ/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2679SX-ADJ/NOPB requirements.
6.How does Aetrix verify that LM2679SX-ADJ/NOPB is sourced from the original manufacturer or authorized distributors?
All LM2679SX-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 LM2679SX-ADJ/NOPB meets industry standards.
7.What is the process for return or replacement of LM2679SX-ADJ/NOPB?
All LM2679SX-ADJ/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM2679SX-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 LM2679SX-ADJ/NOPB part is unused and in its original packaging.
Return procedure for LM2679SX-ADJ/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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