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Texas Instruments LM2679T-3.3/NOPB
- Part No.:
- LM2679T-3.3/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- TO-220-7 Formed Leads
- Datasheet:
-
LM2679T-3.3/NOPB.pdf
- Description:
- IC REG BUCK 3.3V 5A TO220-7
- Quantity:
- Payment:
- Shipping:
Inventory:228
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Product details
Overview
LM2679T-3.3/NOPB from Texas Instruments is a monolithic 5-A step-down (buck) DC/DC regulator with fixed 3.3-V output, 8–40-V input range, 260-kHz fixed-frequency PWM control, 120-mΩ DMOS switch, and ±2% output voltage tolerance over line/load/temperature. It delivers high-efficiency power conversion in industrial power supplies and battery-charger pre-regulators.
For engineers reviewing the LM2679T-3.3/NOPB datasheet, LM2679T-3.3/NOPB pinout, LM2679T-3.3/NOPB application, or LM2679T-3.3/NOPB equivalent, key selection criteria include programmable current limit (5.5–7.6 A), soft-start timing control, thermal shutdown protection, and compatibility with standard off-the-shelf inductors and low-ESR output capacitors.
Technical Context
The LM2679T-3.3/NOPB integrates a high-side DMOS power switch with 120-mΩ RDS(ON), driven by a fixed 260-kHz oscillator and internal PWM controller. Its feedback loop uses a precision 1.21-V reference and high-gain amplifier to regulate output voltage via direct connection to VOUT for fixed versions.
Current limiting is resistor-programmable (RADJ = 5.6 kΩ sets 6.3-A typical peak limit), while soft-start is implemented via external capacitor on SS pin to control duty-cycle ramp. Thermal shutdown activates at ~160°C junction temperature, and bootstrapping is handled via CB pin connected to SW through a 0.01-μF capacitor.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output voltage | Fixed 3.3 V ±2% over full line, load, and –40°C to 125°C junction range - ensures stable logic rail generation without external divider. |
| Input voltage range | 8 V to 40 V - supports wide-range industrial inputs including 12-V, 24-V, and 36-V nominal systems. |
| Max output current | 5 A continuous - enables single-chip regulation for mid-power embedded systems and motor drivers. |
| Switch RDS(ON) | 0.14 Ω typical at 25°C - minimizes conduction loss and enables >90% efficiency at 5-A load with 12-V input. |
| Oscillator frequency | 260 kHz ±11% - enables use of compact, low-cost off-the-shelf inductors (e.g., 10–22 μH) and reduces EMI compared to MHz-class converters. |
| Current limit range | 5.5 A to 7.6 A (via RADJ = ∞ to 5.6 kΩ) - allows precise fault-current tailoring to protect downstream circuitry without oversized external components. |
| Soft-start control | Capacitor-programmable ramp on SS pin - eliminates input surge current during power-up, reducing stress on upstream supply and bulk capacitors. |
Pinout & Package
LM2679T-3.3/NOPB is packaged in TO-263 (KTW) - a 7-pin surface-mount package with exposed thermal pad (DAP), 10.10 mm × 8.89 mm body size, and vertical heat dissipation capability.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (SW) | Switch output | Drain node of internal DMOS FET; connects to inductor and Schottky diode cathode - must be routed with minimal loop area to reduce EMI and switching losses. |
| 2 (VIN) | Input supply | Main power input (8–40 V); requires low-ESR ceramic bypass capacitors placed adjacent to pin - critical for stable high-frequency operation. |
| 3 (CB) | Bootstrap capacitor | Connects to SW via 0.01-μF capacitor; provides gate-drive voltage above VIN to fully enhance internal high-side switch - essential for low RDS(ON). |
| 4 (GND) | Power ground | Primary return path for input/output currents and IC bias; must connect directly to thermal pad and low-impedance ground plane to ensure thermal performance and noise immunity. |
| 5 (IADJ) | Current limit adjust | Accepts resistor to GND to set peak switch current (ICL = 37,125 / RADJ); open-circuit defaults to max limit - enables overcurrent protection tuning without sense resistors. |
| 6 (FB) | Feedback input | Direct connection to output for fixed 3.3-V version; internal resistor divider sets regulation point - eliminates external components and improves accuracy vs. adjustable variants. |
| 7 (SS) | Soft-start | Capacitor-to-ground sets output voltage ramp time; floating disables soft-start - prevents inrush into large output capacitance or downstream LDOs. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 120-mΩ DMOS switch | Enables 5-A output without external MOSFETs; reduces BOM count and layout complexity while maintaining >90% efficiency at full load. |
| Resistor-programmable current limit | Allows precise fault-current setting (3–7 A range) using one external resistor - replaces discrete current-sense circuits and improves system reliability under short-circuit conditions. |
| Fixed 3.3-V output with ±2% tolerance | Meets tight regulation requirements for FPGA, microprocessor I/O, and USB-powered peripherals without trimming or calibration. |
| 260-kHz fixed-frequency operation | Permits use of standardized, low-cost power inductors and simplifies EMI filtering design versus variable-frequency alternatives. |
| Thermal shutdown + soft-start | Protects against overheating during overload or poor heatsinking; soft-start prevents input capacitor stress and downstream voltage droop during startup. |
Applications
| Industrial Power Supply | Automotive Battery Charger |
|---|---|
|
Use Scenario: Converting 24-V vehicle battery or 36-V industrial bus to regulated 3.3-V logic rail for CAN controllers and sensor interfaces. IC Role / Device Role / Timing Role: Primary buck regulator providing isolated, low-noise 3.3-V supply with built-in overcurrent and thermal protection. Use Value: Eliminates need for external current-sense resistors and discrete MOSFET drivers; maintains ±2% output accuracy across –40°C to 125°C ambient. |
Use Scenario: Pre-regulating unregulated alternator or charger output before linear post-regulation for sensitive analog circuitry. IC Role / Device Role / Timing Role: High-efficiency (>90%) step-down stage delivering up to 5 A to intermediate bus, reducing heat in downstream LDOs. Use Value: Reduces thermal load by >50% vs. linear preregulator; programmable current limit matches battery charge profile without redesign. |
| Embedded System Power | Programmable Logic Supply |
|
Use Scenario: Powering ARM Cortex-M7 microcontrollers and peripheral I/O banks requiring clean, stable 3.3-V rails in factory automation equipment. IC Role / Device Role / Timing Role: Main DC/DC converter with integrated soft-start to prevent brownout during cold boot and ensure deterministic firmware initialization. Use Value: Direct FB connection eliminates feedback resistor drift errors; TO-263 thermal pad enables conduction cooling in sealed enclosures. |
Use Scenario: Supplying configuration voltage to Xilinx Spartan-7 or Intel MAX 10 FPGAs where 3.3-V I/O banks require fast transient response and low ripple. IC Role / Device Role / Timing Role: High-current buck regulator with <100-μs load-step recovery, leveraging fixed 260-kHz frequency for predictable loop stability. Use Value: Achieves <50-mV output deviation under 0–5-A 100-μs load steps; ±2% tolerance ensures reliable I/O voltage margin compliance. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2678T-3.3/NOPB | Lower 3-A output rating, same 260-kHz frequency and TO-263 package; lacks programmable current limit - fixed 3-A limit. | Suitable only for sub-3-A loads; cannot support 5-A FPGA core rails or high-current motor drivers. | Select when cost sensitivity outweighs current headroom needs and thermal margin is sufficient. |
| TPS54560BQDDARQ1 | Automotive-grade 60-V input, 5-A synchronous buck; 100–2500-kHz adjustable frequency; no external bootstrap capacitor required. | Supports higher input voltages and wider temperature range (–40°C to 150°C); requires external compensation but offers better light-load efficiency. | Choose for automotive or harsh-environment designs needing AEC-Q100 qualification and extended input range. |
Compared with LM2678T-3.3/NOPB, LM2679T-3.3/NOPB delivers 67% higher current capacity and field-programmable fault protection; versus TPS54560BQDDARQ1, it offers simpler layout (no external compensation) and lower BOM cost but lacks automotive qualification and synchronous rectification.
Availability
LM2679T-3.3/NOPB is available at Aetrix Electronics and suitable for industrial power supplies, automotive battery chargers, and embedded system power rails requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LM2679T-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 specializing in analog and embedded processing technologies, with leadership in power management ICs since the 1980s.
The LM2679 series belongs to TI's SIMPLE SWITCHER® family - designed for rapid, reliable DC/DC converter implementation using minimal external components and industry-standard magnetics.
FAQ
What is the maximum input voltage rating for LM2679T-3.3/NOPB?
The absolute maximum input voltage for LM2679T-3.3/NOPB is 45 V, but the recommended operating range is 8 V to 40 V. Operation above 40 V risks exceeding safe operating area limits and may trigger overvoltage protection or cause permanent damage. For 40-V nominal systems, derating is advised to maintain reliability across temperature extremes.
Does LM2679T-3.3/NOPB require an external feedback resistor divider?
No, LM2679T-3.3/NOPB does not require an external feedback resistor divider. As a fixed-output variant, it contains internal precision resistors that set the 3.3-V regulation point; the FB pin is connected directly to the output capacitor for closed-loop control - eliminating component tolerance errors and simplifying layout.
How is current limit configured on LM2679T-3.3/NOPB?
Current limit on LM2679T-3.3/NOPB is configured by connecting a resistor (RADJ) between the IADJ pin and GND. With RADJ = 5.6 kΩ, the typical peak switch current is 6.3 A. The relationship is ICL = 37,125 / RADJ (in ohms), allowing adjustment from 3 A to 7 A - enabling precise fault-current matching without external sensing elements.
What package type is used for LM2679T-3.3/NOPB and what are its thermal characteristics?
LM2679T-3.3/NOPB uses the TO-263 (KTW) package - a 7-pin surface-mount device with exposed thermal pad. When mounted on 0.4896 in² copper area, its junction-to-ambient thermal resistance is 35°C/W; with 1.0064 in² copper, it drops to 26°C/W - enabling 5-A operation without forced air cooling in properly designed PCB layouts.
Can LM2679T-3.3/NOPB operate without a soft-start capacitor?
Yes, LM2679T-3.3/NOPB can operate without a soft-start capacitor: leaving the SS pin floating disables the soft-start function. However, omitting the capacitor increases input surge current during startup, potentially stressing input capacitors and causing upstream supply droop - especially with large output capacitance (>1000 μF) or high-input-voltage conditions.
LM2679T-3.3/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- SIMPLE SWITCHER®
- Package/Case:
- TO-220-7 Formed Leads
- Packaging:
- Tube
- 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:
- Through Hole
- Supplier Device Package:
- TO-220-7
LM2679T-3.3/NOPB FAQ
1.How can I place an order for LM2679T-3.3/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2679T-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 LM2679T-3.3/NOPB reliable?
The price and inventory of LM2679T-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 LM2679T-3.3/NOPB is usually 5 days.
3.What payment methods are accepted for LM2679T-3.3/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2679T-3.3/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2679T-3.3/NOPB?
LM2679T-3.3/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2679T-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 LM2679T-3.3/NOPB?
For technical support, including LM2679T-3.3/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2679T-3.3/NOPB requirements.
6.How does Aetrix verify that LM2679T-3.3/NOPB is sourced from the original manufacturer or authorized distributors?
All LM2679T-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 LM2679T-3.3/NOPB meets industry standards.
7.What is the process for return or replacement of LM2679T-3.3/NOPB?
All LM2679T-3.3/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM2679T-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 LM2679T-3.3/NOPB part is unused and in its original packaging.
Return procedure for LM2679T-3.3/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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