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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 Topology Buck Iout (max) (A) 5 Vin (max) (V) 40 Vin (min) (V) 8 Vout (max) (V) 37 Vout (min) (V) 1.23 Features 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 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) TO-220 (NDZ) 7 82.6008 mm² (10.16 mm × 8.13 mm) VSON (NHM) 14 30 mm² (6 mm × 5 mm)
  • Efficiency up to 92%
  • Simple and easy to design using off-the-shelf external components
  • 120mΩ DMOS output switch
  • 3.3V, 5V, and 12V fixed output and adjustable (1.2V to 37V) versions
  • 50µA standby current when switched OFF
  • ±2% maximum output tolerance over full line and load conditions
  • 8V to 40V wide input voltage range
  • 260kHz 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
  • 120mΩ DMOS output switch
  • 3.3V, 5V, and 12V fixed output and adjustable (1.2V to 37V) versions
  • 50µA standby current when switched OFF
  • ±2% maximum output tolerance over full line and load conditions
  • 8V to 40V wide input voltage range
  • 260kHz 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 5A 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 3.3V, 5V, and 12V and an adjustable output version.

The SIMPLE SWITCHER power converter concept provides for a complete design using a minimum number of external components. A high fixed frequency oscillator (260kHz) 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 and OFF control input that can power down the regulator to a low 50µA quiescent current standby condition. The output voltage is specified 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 5A 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 3.3V, 5V, and 12V and an adjustable output version.

The SIMPLE SWITCHER power converter concept provides for a complete design using a minimum number of external components. A high fixed frequency oscillator (260kHz) 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 and OFF control input that can power down the regulator to a low 50µA quiescent current standby condition. 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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Top documentation Type Title Format options Date
* Data sheet LM2678 SIMPLE SWITCHER Power Converter, High-Efficiency, 5A, Step-Down Voltage Regulator datasheet (Rev. L) PDF | HTML Jun 25, 2025
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

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
Supported products & hardware
Simulation model

LM2678 Unencrypted PSpice Average Model Package (Rev. A)

SNVM039A.ZIP (56 KB) - PSpice model
Supported products & hardware
Simulation model

LM2678 Unencrypted PSpice Transient Model

SNVM880.ZIP (3 KB) - PSpice model
Supported products & hardware
Simulation model

LM2678 Unencrypted PSpice Transient Model Package (Rev. A)

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