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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > Voltage Regulators - DC DC Switching Regulators

Texas Instruments LM2679S-3.3

Name: LM2679S-3.3
Brand: Texas Instruments
SKU: LM2679S-3.3
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: LM2679S-3.3

Manufacturer:: Texas Instruments

Category:: Voltage Regulators - DC DC Switching Regulators

Package:: TO-263-8, D2PAK (7 Leads + Tab), TO-263CA

Datasheet:: LM2679S-3.3.pdf

Description:: IC REG BUCK 3.3V 5A TO263

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Product details

Overview

LM2679S-3.3 from Texas Instruments is a monolithic 5-A step-down (buck) DC/DC voltage regulator with fixed 3.3-V output, 8 V to 40 V input range, 260-kHz fixed-frequency PWM control, ±2% output voltage tolerance, and resistor-programmable current limit (5.5–7.6 A typical at RADJ = 5.6 kΩ). It integrates a 120-mΩ DMOS high-side switch and supports soft-start for inrush current control in industrial power supplies.

For engineers reviewing the LM2679S-3.3 datasheet, LM2679S-3.3 pinout, LM2679S-3.3 application, or LM2679S-3.3 equivalent, key selection considerations include its fixed 3.3-V output, wide 8–40 V input compatibility, thermal shutdown protection, adjustable current limit via external resistor, and TO-263-7 package with exposed DAP for enhanced thermal performance.

Technical Context

The LM2679S-3.3 implements a fixed-frequency (260 kHz) current-mode PWM controller driving an integrated 120-mΩ DMOS high-side switch. Its feedback loop uses an internal 1.21-V reference and direct FB-to-output connection for fixed-output variants, eliminating external resistive dividers.

Current limiting is set by a resistor from the Current_adjust pin to GND, establishing ICL = 37,125 / RADJ (A), enabling precise peak-current tailoring from 3 A to 7 A. Soft-start is implemented via an external capacitor on the SS pin, controlling output voltage ramp rate to suppress input surge current during startup.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Voltage	Fixed 3.3 V ±2% over full line/load/temperature (–40°C to 125°C), enabling stable logic supply without feedback divider.
Input Voltage Range	8 V to 40 V DC - supports wide-input industrial, automotive, and telecom power rails without pre-regulation.
Max Output Current	5 A continuous - sufficient for FPGA core supplies, DSPs, and multi-rail embedded systems.
Switch ON-Resistance	0.12 Ω typical at 25°C - minimizes conduction loss and improves efficiency up to 92% at optimal conditions.
Oscillator Frequency	260 kHz fixed - enables use of compact, off-the-shelf inductors and reduces EMI compared to higher-frequency alternatives.
Current Limit Range	5.5 A to 7.6 A (typical) via 5.6 kΩ–12.4 kΩ RADJ - allows safe operation under short-circuit or overload without external sensing.
Quiescent Current	4.2–6 mA - low standby draw suitable for always-on industrial controllers and remote sensors.
Junction Temp Range	–40°C to +125°C - qualified for harsh environments including motor drives and outdoor infrastructure.

Pinout & Package

LM2679S-3.3 is packaged in TO-263-7 (KTW) with exposed die attach paddle (DAP) for thermal dissipation. The DAP must be soldered to a PCB copper area ≥0.136 in² (3.45 cm²) for RθJA ≤56°C/W, or ≥0.4896 in² (12.44 cm²) for RθJA ≤35°C/W.

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 and EMI.
2 (Input)	Main power input	Connects to 8–40 V source and high-frequency input bypass capacitors (3 × 15 µF/50 V recommended); shortest possible trace to GND.
3 (CB)	Bootstrap capacitor terminal	Connects 0.01 µF ceramic capacitor to Switch_output (Pin 1); enables gate drive above VIN for full MOSFET enhancement.
4 (GND)	Power ground	Common return for input/output capacitors, current sense, and thermal pad; must tie directly to large copper plane.
5 (Current_adjust)	Peak current limit programming	Resistor to GND sets ICL = 37,125 / RADJ (Ω); 5.6 kΩ yields ~6.3 A typical limit for robust 5-A operation.
6 (FB)	Feedback reference input	Internally connected to output for fixed 3.3-V version - no external divider needed; sensitive to noise, keep away from inductor.
7 (SS)	Soft-start timing input	Capacitor to GND (e.g., 1 nF) controls output voltage ramp time; floating disables soft-start.

Key Features

Feature	Design Value
Integrated 120-mΩ DMOS switch	Enables high-efficiency (>90%) 5-A buck conversion without external MOSFETs or complex gate drivers.
Resistor-programmable current limit	Allows precise fault-current setting (3–7 A) using one external resistor - eliminates need for current-sense amplifiers or shunts.
Fixed 3.3-V output with ±2% tolerance	Guarantees compliance with 3.3-V logic supply requirements (e.g., PCIe, USB, ARM SoCs) across temperature and load.
260-kHz fixed-frequency oscillator	Permits use of standardized, low-cost, high-current inductors and simplifies EMI filter design versus variable-frequency controllers.
Thermal shutdown & soft-start	Protects against overheating during sustained overload and prevents input surge current damage during cold start.
TO-263-7 package with thermal pad	Supports >5 A continuous operation with proper PCB copper area - superior thermal performance vs. TO-220 for space-constrained designs.

Applications

Industrial PLC Power Supply	Automotive Body Control Module
Use Scenario: Provides clean 3.3-V rail for microcontrollers, CAN transceivers, and sensor interfaces in programmable logic controllers operating from 24-V DC bus. IC Role / Device Role / Timing Role: Primary step-down regulator delivering regulated 3.3 V at up to 5 A, replacing linear regulators to reduce heat and improve efficiency. Use Value: Eliminates need for heatsinks and enables compact, fanless enclosure design while maintaining ±2% output stability across –40°C to 85°C ambient.	Use Scenario: Powers 3.3-V MCU and digital peripherals in body control units supplied from 12-V battery with load-dump transients up to 40 V. IC Role / Device Role / Timing Role: Input-tolerant buck converter handling wide 8–40 V input range and providing current-limited protection during short-circuit faults. Use Value: Resists automotive load-dump events without external TVS, and programmable current limit avoids fuse replacement during intermittent shorts.
Telecom Remote Radio Unit	FPGA Core Supply
Use Scenario: Generates 3.3-V bias for RF front-end ICs and baseband processors in outdoor small-cell radios powered from 48-V PoE-derived supply. IC Role / Device Role / Timing Role: High-current preregulator stepping 48 V down to 3.3 V before LDO post-regulation, reducing thermal stress on downstream regulators. Use Value: Achieves >82% efficiency at 5 A (VIN = 12 V), minimizing board-level heat generation critical for sealed, passive-cooled enclosures.	Use Scenario: Supplies configurable logic fabric and I/O banks in Xilinx Artix-7 or Intel Cyclone V FPGAs requiring tightly regulated 3.3-V auxiliary rail. IC Role / Device Role / Timing Role: Fixed-output buck regulator with fast transient response and low output ripple (<30 mV pk-pk) for noise-sensitive digital cores. Use Value: Delivers stable 3.3 V with <±2% error across 100 mA–5 A load steps, preventing configuration errors or timing violations during FPGA reconfiguration.

Industrial PLC Power Supply

Automotive Body Control Module

Use Scenario: Provides clean 3.3-V rail for microcontrollers, CAN transceivers, and sensor interfaces in programmable logic controllers operating from 24-V DC bus.

IC Role / Device Role / Timing Role: Primary step-down regulator delivering regulated 3.3 V at up to 5 A, replacing linear regulators to reduce heat and improve efficiency.

Use Value: Eliminates need for heatsinks and enables compact, fanless enclosure design while maintaining ±2% output stability across –40°C to 85°C ambient.

Use Scenario: Powers 3.3-V MCU and digital peripherals in body control units supplied from 12-V battery with load-dump transients up to 40 V.

IC Role / Device Role / Timing Role: Input-tolerant buck converter handling wide 8–40 V input range and providing current-limited protection during short-circuit faults.

Use Value: Resists automotive load-dump events without external TVS, and programmable current limit avoids fuse replacement during intermittent shorts.

Telecom Remote Radio Unit

FPGA Core Supply

Use Scenario: Generates 3.3-V bias for RF front-end ICs and baseband processors in outdoor small-cell radios powered from 48-V PoE-derived supply.

IC Role / Device Role / Timing Role: High-current preregulator stepping 48 V down to 3.3 V before LDO post-regulation, reducing thermal stress on downstream regulators.

Use Value: Achieves >82% efficiency at 5 A (VIN = 12 V), minimizing board-level heat generation critical for sealed, passive-cooled enclosures.

Use Scenario: Supplies configurable logic fabric and I/O banks in Xilinx Artix-7 or Intel Cyclone V FPGAs requiring tightly regulated 3.3-V auxiliary rail.

IC Role / Device Role / Timing Role: Fixed-output buck regulator with fast transient response and low output ripple (<30 mV pk-pk) for noise-sensitive digital cores.

Use Value: Delivers stable 3.3 V with <±2% error across 100 mA–5 A load steps, preventing configuration errors or timing violations during FPGA reconfiguration.

Equivalent & Alternatives

The following parts are listed as comparable options for similar step-down regulator applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
LM2678-3.3	Same pinout, but 3-A rated (vs. 5-A); lower RDS(ON) = 150 mΩ; no current-adjust pin - fixed 5.5-A limit.	Suitable only for ≤3-A loads; lacks programmable current limit and soft-start flexibility.	Select when cost sensitivity outweighs current headroom and programmability needs.
TPS54560B	60-V input, 5-A synchronous buck; 2.5-V to 60-V input; no external diode needed; 100-kHz to 2.5-MHz adjustable frequency.	Requires external compensation; more complex layout; higher BOM count but better light-load efficiency.	Prefer for ultra-wide input (e.g., 12–60 V) or where synchronous rectification improves system efficiency.

Compared with LM2678-3.3, LM2679S-3.3 delivers 67% higher current capability and field-programmable fault protection; versus TPS54560B, it offers simpler design with integrated diode drive and fixed-frequency stability, at the cost of lower input voltage ceiling and no synchronization capability.

Availability

LM2679S-3.3 is available at Aetrix Electronics and suitable for industrial automation, automotive electronics, and telecom infrastructure requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for LM2679S-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 and embedded processing technologies, with decades of expertise in power management ICs and high-reliability industrial components.

The LM2679 series belongs to TI's SIMPLE SWITCHER® family - designed specifically for ease-of-use in non-isolated DC/DC buck conversion, targeting engineers needing robust, high-current regulation with minimal external components.

FAQ

What is the maximum input voltage rating for LM2679S-3.3?

The absolute maximum input voltage for LM2679S-3.3 is 45 V, but the recommended operating range is 8 V to 40 V DC. Operation at 40 V is supported across the full temperature range (–40°C to 125°C junction), making LM2679S-3.3 suitable for 24-V and 36-V industrial systems with transient margin. Exceeding 40 V risks exceeding SOA limits during load transients.

Does LM2679S-3.3 require an external Schottky diode?

Yes, LM2679S-3.3 requires an external Schottky diode connected from the Switch_output pin (Pin 1) to the output rail. The IC integrates only the high-side DMOS switch; the diode provides the freewheeling path during switch-off. A 60-V, 6-A Schottky (e.g., 6TQ045S) is recommended per TI's typical application circuit for LM2679S-3.3.

How is the current limit set on LM2679S-3.3?

The current limit on LM2679S-3.3 is set by connecting a resistor (RADJ) between the Current_adjust pin (Pin 5) and GND. The peak switch current follows ICL = 37,125 / RADJ (in ohms), yielding 6.3 A typical with 5.6 kΩ. This allows precise, resistor-based tuning from 3 A to 7 A - a key differentiator versus fixed-limit alternatives like LM2678-3.3.

What package options are available for LM2679S-3.3?

LM2679S-3.3 is offered in three packages: TO-263-7 (KTW), TO-220-7 (NDZ), and VSON-14 (NHM). The TO-263-7 variant - used in the "S" suffix part - features an exposed thermal pad (DAP) and is optimized for high-current, thermally demanding applications. Thermal resistance drops to 26°C/W with adequate PCB copper area.

Can LM2679S-3.3 be used in adjustable-output configurations?

No - LM2679S-3.3 is a fixed-output variant with internal feedback resistors set for 3.3 V. To implement adjustable output (1.2 V to 37 V), the LM2679-ADJ part must be used instead, which requires external resistor divider on the FB pin. Using LM2679S-3.3 in adjustable mode is not supported; its FB pin is internally tied to the output and lacks the 1.21-V reference access needed for external programming.

LM2679S-3.3 Specifications

Product attributes: Attribute value

Manufacturer:: Texas Instruments

Series:: SIMPLE SWITCHER®

Package/Case:: TO-263-8, D2PAK (7 Leads + Tab), TO-263CA

Packaging:: Tube

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:: TO-263 (DDPAK-7)

LM2679S-3.3 FAQ

1.How can I place an order for LM2679S-3.3 through Aetrix?

Please submit a Request for Quotation (RFQ) for LM2679S-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 LM2679S-3.3 reliable?

The price and inventory of LM2679S-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 LM2679S-3.3 is usually 5 days.

3.What payment methods are accepted for LM2679S-3.3?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2679S-3.3 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for LM2679S-3.3?

LM2679S-3.3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your LM2679S-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 LM2679S-3.3?

For technical support, including LM2679S-3.3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2679S-3.3 requirements.

6.How does Aetrix verify that LM2679S-3.3 is sourced from the original manufacturer or authorized distributors?

All LM2679S-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 LM2679S-3.3 meets industry standards.

7.What is the process for return or replacement of LM2679S-3.3?

All LM2679S-3.3 units undergo pre-shipment inspection (PSI). If there is an issue with LM2679S-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 LM2679S-3.3 part is unused and in its original packaging.

Return procedure for LM2679S-3.3:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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