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AC/DC & DC/DC converters (integrated FET)

LM2678

ACTIVE

8V to 40V, 5A SIMPLE SWITCHER® buck converter with high efficiency

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Data sheet

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LM2678

ACTIVE
Data sheet Order now

Product details

Rating Catalog Operating temperature range (°C) -40 to 125 Topology Buck Type Converter Iout (max) (A) 5 Vin (min) (V) 8 Vin (max) (V) 40 Switching frequency (min) (kHz) 260 Switching frequency (max) (kHz) 260 Features Frequency synchronization, Over Current Protection Control mode Voltage mode Vout (min) (V) 1.23 Vout (max) (V) 37 Iq (typ) (µA) 4200 Duty cycle (max) (%) 91
Rating Catalog Operating temperature range (°C) -40 to 125 Topology Buck Type Converter Iout (max) (A) 5 Vin (min) (V) 8 Vin (max) (V) 40 Switching frequency (min) (kHz) 260 Switching frequency (max) (kHz) 260 Features Frequency synchronization, Over Current Protection Control mode Voltage mode Vout (min) (V) 1.23 Vout (max) (V) 37 Iq (typ) (µA) 4200 Duty cycle (max) (%) 91
TO-220 (NDZ) 7 82.6008 mm² 10.16 x 8.13 TO-263 (KTW) 7 153.924 mm² 10.1 x 15.24 VSON (NHM) 14 30 mm² 6 x 5
  • Efficiency Up to 92%
  • Simple and Easy to Design Using Off-the-Shelf External Components
  • 120-mΩ DMOS Output Switch
  • 3.3-V, 5-V, and 12-V Fixed Output and Adjustable (1.2 V to 37 V) Versions
  • 50-µA Standby Current When Switched OFF
  • ±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
  • –40 to 125°C Operating Junction Temperature Range
  • Create a Custom Design Using the LM2678 With the WEBENCH® Power Designer
  • Efficiency Up to 92%
  • Simple and Easy to Design Using Off-the-Shelf External Components
  • 120-mΩ DMOS Output Switch
  • 3.3-V, 5-V, and 12-V Fixed Output and Adjustable (1.2 V to 37 V) Versions
  • 50-µA Standby Current When Switched OFF
  • ±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
  • –40 to 125°C Operating Junction Temperature Range
  • Create a Custom Design Using the LM2678 With the WEBENCH® Power Designer

The LM2678 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 LM2678 are available from several manufacturers to greatly simplify the design process.

The LM2678 series also has built-in thermal shutdown, current limiting, and an ON/OFF control input that can power down the regulator to a low 50-µA quiescent current standby condition. The output voltage is ensured to a ±2% tolerance. The clock frequency is controlled to within a ±11% tolerance.

The LM2678 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 LM2678 are available from several manufacturers to greatly simplify the design process.

The LM2678 series also has built-in thermal shutdown, current limiting, and an ON/OFF control input that can power down the regulator to a low 50-µA quiescent current standby condition. The output voltage is ensured to a ±2% tolerance. The clock frequency is controlled to within a ±11% tolerance.
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Technical documentation

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Type Title Date
* Data sheet LM2678 SIMPLE SWITCHER High Efficiency 5-A Step-Down Voltage Regulator datasheet (Rev. K) PDF | HTML 13 Jan 2017
Application note Semiconductor and IC Package Thermal Metrics (Rev. D) PDF | HTML 25 Mar 2024
Technical article Quantifying the value of wide VIN PDF | HTML 15 Jun 2016
Technical article DC/DC converter datasheets – System losses demystified PDF | HTML 25 Apr 2016
Technical article DC/DC converter datasheets – System efficiency demystified PDF | HTML 18 Apr 2016
Application note Low EMI Layout Made SIMPLE With LM43600/1/2/3 and LM46000/1/2 (Rev. A) 12 Sep 2014
Application note AN-1187 Leadless Leadframe Package (LLP) (Rev. R) 07 May 2013
EVM User's guide AN-1135 LM267X 3A, 5A Evaluation Boards (Rev. D) 24 Apr 2013
Application note AN-2162 Simple Success With Conducted EMI From DC-DC Converters (Rev. C) 24 Apr 2013
Application note AN-1149 Layout Guidelines for Switching Power Supplies (Rev. C) 23 Apr 2013
Application note AN-1197 Selecting Inductors for Buck Converters (Rev. B) 23 Apr 2013
Application note AN-1229 SIMPLE SWITCHER PCB Layout Guidelines (Rev. C) 23 Apr 2013
Application note AN-1246 Stresses in Wide Input DC-DC Converters (Rev. C) 23 Apr 2013
Application note AN-1520 A Guide to Board Layout for Best Thermal Resistance for Exposed Packages (Rev. B) 23 Apr 2013
Application note AN-1566 Techniques for Thermal Analysis of Switching Power Supply Designs (Rev. A) 23 Apr 2013
Application note AN-1889 How to Measure the Loop Transfer Function of Power Supplies (Rev. A) 23 Apr 2013
Application note AN-1Positive-to-Negative Buck-Boost Converter Using LM267x SIMPLE SWITCHER (Rev. E) 23 Apr 2013
Application note AN-2155 Layout Tips for EMI Reduction in DC/ DC Converters (Rev. A) 23 Apr 2013
Application note Simple Techniques Minimize Cross-Coupling in Distributed Power Systems 21 Mar 2007
Application note Input and Output Capacitor Selection 19 Sep 2005
More literature SEM1600 Topic 4: Constructing Your Power Supply – Layout Considerations 12 Jul 2005
Application note AN-643 EMI/RFI Board Design (Rev. B) 03 May 2004

Design & development

For additional terms or required resources, click any title below to view the detail page where available.

Simulation model

LM2678 Unencrypted PSpice Average Model

SNVM879.ZIP (1 KB) - PSpice Model
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Simulation model

LM2678 Unencrypted PSpice Average Model Package (Rev. A)

SNVM039A.ZIP (56 KB) - PSpice Model
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Simulation model

LM2678 Unencrypted PSpice Transient Model

SNVM880.ZIP (3 KB) - PSpice Model
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Simulation model

LM2678 Unencrypted PSpice Transient Model Package (Rev. A)

SNVM038A.ZIP (63 KB) - PSpice Model
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Package Pins CAD symbols, footprints & 3D models
TO-220 (NDZ) 7 Ultra Librarian
TO-263 (KTW) 7 Ultra Librarian
VSON (NHM) 14 Ultra Librarian
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