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LM2679

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SIMPLE SWITCHER® 8V to 40V, 5A Step-Down DC/DC Switching Regulator with Adjustable Current Limit

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Data sheet

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LM2679

ACTIVE
Data sheet Order now

Product details

Rating Catalog Topology Buck Iout (max) (A) 5 Vin (max) (V) 40 Vin (min) (V) 8 Vout (max) (V) 37 Vout (min) (V) 1.23 Features Adjustable current limit, Frequency synchronization, Over Current Protection Control mode Voltage mode Operating temperature range (°C) -40 to 125 Iq (typ) (A) 0.0042 Duty cycle (max) (%) 91
Rating Catalog Topology Buck Iout (max) (A) 5 Vin (max) (V) 40 Vin (min) (V) 8 Vout (max) (V) 37 Vout (min) (V) 1.23 Features Adjustable current limit, Frequency synchronization, Over Current Protection Control mode Voltage mode Operating temperature range (°C) -40 to 125 Iq (typ) (A) 0.0042 Duty cycle (max) (%) 91
TO-263 (KTW) 7 153.924 mm² (10.1 mm × 15.24 mm) VSON (NHM) 14 30 mm² (6 mm × 5 mm) TO-220 (NDZ) 7 82.6008 mm² (10.16 mm × 8.13 mm)
  • Efficiency Up to 92%
  • Simple and Easy to Design Using Off-The-Shelf
    External Components
  • Resistor Programmable Peak Current Limit Over a
    Range of 3 A to 7 A
  • 120-mΩ DMOS Output Switch
  • 3.3-V, 5-V, 12-V Fixed Output and Adjustable
    (1.2 V to 37 V) Versions
  • ±2% Maximum Output Tolerance Over Full Line
    and Load Conditions
  • Wide Input Voltage Range: 8 V to 40 V
  • 260-kHz Fixed Frequency Internal Oscillator
  • Soft-Start Capability
  • –40 to 125°C Operating Junction Temperature
    Range
  • Efficiency Up to 92%
  • Simple and Easy to Design Using Off-The-Shelf
    External Components
  • Resistor Programmable Peak Current Limit Over a
    Range of 3 A to 7 A
  • 120-mΩ DMOS Output Switch
  • 3.3-V, 5-V, 12-V Fixed Output and Adjustable
    (1.2 V to 37 V) Versions
  • ±2% Maximum Output Tolerance Over Full Line
    and Load Conditions
  • Wide Input Voltage Range: 8 V to 40 V
  • 260-kHz Fixed Frequency Internal Oscillator
  • Soft-Start Capability
  • –40 to 125°C Operating Junction Temperature
    Range

The LM2679 series of regulators are monolithic integrated circuits which provide all of the active functions for a step-down (buck) switching regulator capable of driving up to 5-A loads with excellent line and load regulation characteristics. High efficiency (>90%) is obtained through the use of a low ON-resistance DMOS power switch. The series consists of fixed output voltages of 3.3 V, 5 V, and 12 V and an adjustable output version.

The SIMPLE SWITCHER® concept provides for a complete design using a minimum number of external components. A high fixed frequency oscillator (260 kHz) allows the use of physically smaller sized components. A family of standard inductors for use with the LM2679 are available from several manufacturers to greatly simplify the design process.

Other features include the ability to reduce the input surge current at power on by adding a soft-start timing capacitor to gradually turn on the regulator. The LM2679 series also has built-in thermal shutdown and resistor programmable current limit of the power MOSFET switch to protect the device and load circuitry under fault conditions. The output voltage is specified to a ±2% tolerance. The clock frequency is controlled to within a ±11% tolerance.

The LM2679 series of regulators are monolithic integrated circuits which provide all of the active functions for a step-down (buck) switching regulator capable of driving up to 5-A loads with excellent line and load regulation characteristics. High efficiency (>90%) is obtained through the use of a low ON-resistance DMOS power switch. The series consists of fixed output voltages of 3.3 V, 5 V, and 12 V and an adjustable output version.

The SIMPLE SWITCHER® concept provides for a complete design using a minimum number of external components. A high fixed frequency oscillator (260 kHz) allows the use of physically smaller sized components. A family of standard inductors for use with the LM2679 are available from several manufacturers to greatly simplify the design process.

Other features include the ability to reduce the input surge current at power on by adding a soft-start timing capacitor to gradually turn on the regulator. The LM2679 series also has built-in thermal shutdown and resistor programmable current limit of the power MOSFET switch to protect the device and load circuitry under fault conditions. The output voltage is specified to a ±2% tolerance. The clock frequency is controlled to within a ±11% tolerance.
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Technical documentation

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* Data sheet LM2679 SIMPLE SWITCHER 5-A Step-Down Voltage Regulator With Adjustable Current Limit datasheet (Rev. O) PDF | HTML Jun 29, 2016
Application note Semiconductor and IC Package Thermal Metrics (Rev. D) PDF | HTML Mar 25, 2024
Technical article Quantifying the value of wide VIN PDF | HTML Jun 15, 2016
Technical article DC/DC converter datasheets – System losses demystified PDF | HTML Apr 25, 2016
Technical article DC/DC converter datasheets – System efficiency demystified PDF | HTML Apr 18, 2016
Application note Low EMI Layout Made SIMPLE With LM43600/1/2/3 and LM46000/1/2 (Rev. A) Sep 12, 2014
Application note AN-1187 Leadless Leadframe Package (LLP) (Rev. R) May 7, 2013
Application note AN-2162 Simple Success With Conducted EMI From DC-DC Converters (Rev. C) Apr 24, 2013
Application note AN-1566 Techniques for Thermal Analysis of Switching Power Supply Designs (Rev. A) Apr 23, 2013
Application note AN-2155 Layout Tips for EMI Reduction in DC/ DC Converters (Rev. A) Apr 23, 2013
Application note AN-1229 SIMPLE SWITCHER PCB Layout Guidelines (Rev. C) Apr 23, 2013
Application note AN-1149 Layout Guidelines for Switching Power Supplies (Rev. C) Apr 23, 2013
Application note AN-1889 How to Measure the Loop Transfer Function of Power Supplies (Rev. A) Apr 23, 2013
Application note AN-1Positive-to-Negative Buck-Boost Converter Using LM267x SIMPLE SWITCHER (Rev. E) Apr 23, 2013
Application note AN-1197 Selecting Inductors for Buck Converters (Rev. B) Apr 23, 2013
Application note AN-1246 Stresses in Wide Input DC-DC Converters (Rev. C) Apr 23, 2013
Application note AN-1520 A Guide to Board Layout for Best Thermal Resistance for Exposed Packages (Rev. B) Apr 23, 2013
Application note Simple Techniques Minimize Cross-Coupling in Distributed Power Systems Mar 21, 2007
Application note Input and Output Capacitor Selection Sep 19, 2005
More literature SEM1600 Topic 4: Constructing Your Power Supply – Layout Considerations Jul 12, 2005
Application note AN-643 EMI/RFI Board Design (Rev. B) May 3, 2004

Design & development

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Evaluation board

LM2679-5.0EVAL — SIMPLE SWITCHER® 5A Step-Down Voltage Regulator with Adjustable Current Limit Evaluation Module

Simple Switcher 5A Step-Down Voltage Regulator with Adjustable Current Limit

User guide: PDF
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Simulation model

LM2679 PSpice Transient Model

SNVM485.ZIP (209 KB) - PSpice model
Supported products & hardware
Simulation model

LM2679 Unencrypted PSpice Transient Model

SNVM878.ZIP (2 KB) - PSpice model
Supported products & hardware
Package Pins CAD symbols, footprints & 3D models
TO-263 (KTW) 7 Ultra Librarian
VSON (NHM) 14 Ultra Librarian
TO-220 (NDZ) 7 Ultra Librarian
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