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User's Guide
SNVA013D–December 2000–Revised April 2013
AN-1135 LM267X 3A, 5A Evaluation Boards
1 Introduction
The LM267X evaluation board was developed for the evaluation of LM267X SIMPLE SWITCHER series of
3 Amp and 5 Amp high efficiency step-down (Buck) switching voltage regulators. This application note
describes the printed circuit board, and provides example circuits and directions on setup and operation of
the LM2673S-5_EVAL and LM2679S-5_EVAL evaluation boards.
2 General Description
Many of our boards are intended to provide the user with device characterization and layout optimization
data. The LM267x evaluation board was intended to allow the user to experiment with a variety of circuit
topologies and components, and therefore not optimized for size. Please refer to the discussions of layout
optimization in the PCB Layout Optimization section.
This board was designed such that both through-hole and surface-mount components can be used for
construction. The regulator IC can be placed on the board as a surface-mount component only. The
ground plane serves as a heatsink.
Table 1 shows an overview of the family of devices with special features of each indicated. Consult the
device data sheet, or use the special power supply design software calledSwitchers Made Simple
version 6.X (available for free download from www.ti.com) to determine all necessary component values
for the particular device being used to accomplish a specific design and board layout considerations.
The printed circuit board, PCB, is labeled to indicate the location of all of the needed components for all
possible design options. Table 2 shows a complete list of the component labels and their functions.
Figure 1 identifies all components, but not all are necessary in every design.
Figure 2, Figure 3 and Figure 4 show the top, bottom and silk screen of the printed circuit board
respectively.
Table 1. LM267X Family of High-Current Regulators supported by the Evaluation Board
Device Maximum Load Current (A) Special Features
LM2670 3 ON/OFF, External Frequency Sync Capability
LM2673 3 Adjustable Current Limit, Softstart
LM2676 3 ON/OFF
LM2677 5 ON/OFF, External Frequncy Sync. Capability
LM2678 5 ON/OFF
LM2679 5 Adjustable Current Limit, Softstart
1
SNVA013D–December 2000–Revised April 2013 AN-1135 LM267X 3A, 5A Evaluation Boards
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