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LM2678

ACTIVE

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

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Product details

Vin (min) (V) 8 Vin (max) (V) 40 Vout (min) (V) 1.23 Vout (max) (V) 37 Iout (max) (A) 5 Iq (typ) (mA) 4.2 Switching frequency (min) (kHz) 260 Switching frequency (max) (kHz) 260 Features Frequency synchronization, Over Current Protection Operating temperature range (°C) -40 to 125 Rating Catalog Regulated outputs (#) 1 Control mode Voltage mode Duty cycle (max) (%) 91 Type Converter
Vin (min) (V) 8 Vin (max) (V) 40 Vout (min) (V) 1.23 Vout (max) (V) 37 Iout (max) (A) 5 Iq (typ) (mA) 4.2 Switching frequency (min) (kHz) 260 Switching frequency (max) (kHz) 260 Features Frequency synchronization, Over Current Protection Operating temperature range (°C) -40 to 125 Rating Catalog Regulated outputs (#) 1 Control mode Voltage mode Duty cycle (max) (%) 91 Type Converter
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
Simulation model

LM2678 Unencrypted PSpice Average Model Package (Rev. A)

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

LM2678 Unencrypted PSpice Transient Model

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

LM2678 Unencrypted PSpice Transient Model Package (Rev. A)

SNVM038A.ZIP (63 KB) - PSpice Model
Simulation tool

PSPICE-FOR-TI — PSpice® for TI design and simulation tool

PSpice® for TI is a design and simulation environment that helps evaluate functionality of analog circuits. This full-featured, design and simulation suite uses an analog analysis engine from Cadence®. Available at no cost, PSpice for TI includes one of the largest model libraries in the (...)
Package Pins Download
TO-220 (NDZ) 7 View options
TO-263 (KTW) 7 View options
VSON (NHM) 14 View options

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