Tyco TX 75149 User Manual

StabilityAnalysis T ool

User's Guide

For use withBoardMounted
DC-DCconverters

V1.3

TYCO ELECTRONICSPOWERSYST EMS3000SKYL INEDRIVEMESQU ITE,TX75149

2

Copyright

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* COPYRIGHT 2001, TYCO ELECTRONICS POWER SYSTEMS, INC. *
* ALL INTERNATIONAL RIGHTS RESERVED *
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USER AGREEMENT

-------------­The information contained herein, including the data files and other
documentation (collectively the "Information") has been licensed to you free of
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1

Introduction

The Stability Analysis Tool (SAT) is a Microsoft Excel-based program that
provides a Bode plot of the voltage loop gain of a DC-DC converter for a variety of
external l oa ds. From this plot, informatio n such as crossover frequency and gain and
phase margins can be obtained .

In classical control theory, the stability of a feedback system is assessed by
evaluating its gain and phase margin which are read directly from the Bode plot of
the loop gain. The loop gain of a DC-DC converter dependsnotonlyon the converter
characteristics but also on the load characteristics and the o utput voltage sense
location. This dependence of loop gain on load and sense location makes it
impossible for the power converter manufacturer to determine stability margins in an
actual applicatio n, since the load (especially the number, type and location of output
bulk capacitors, parasitic inductances, etc.) and the output voltage sense location are
unknown. Due to this, in the past if the customer wanted to determine stability
margins, the loop gain would have to be measured using a breadboar d of the power­supply and the load networ k using a networkanaly z er.

The Stability Analysis Tool decouples the combined converter+load system into
two subsystems; one representing the converter and the other representing the load.
Tyco Electronics Power Systems provides converter data files on its web site. The
customer can download the converter data file and import it into the SAT. SAT
allows choosing one of five different configurations to best represent the combination
of load representation and voltage sense location. The tool then allows assessment
of the stability characteristics without the user having to build a prototype of the
power supply and the loadnetwor k andavoidsmaking measureme nts.

System Requirements

SAT v1.3 runs under the followingsy stems:

1) Windows 95, 98, 2000 or Windows NT version4opera tingsystems

2) Microsoft Excel 97 SR-2 or Excel 2000

3) Intel Pentium class or above processorandatleast64MBofRAM

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Installation and Usage

You should first read andaccep t theter mso f the SAT usag e.

 Download the file SAT_v1.3.xls from the Tyco Electronics Power Systems

web site (given below ) to a directoryon your computer .

 Download one or more module datafile(s )tothesam e director y.
 You can start up the tool by following the usual procedures to open an

Excel Worksheet and follow the directions on the screen. Make sure that
the Analysis Toolpak Add-ins are enabled in Excel. Go to Tools menu in
Excel and click on Add-Ins. Check (tick) on A naly sis Toolpack and
Analysis Toolpack – VBA.

Technical Support

For technical support,pleaseco nt actusat

USA Tyco Electronics Power Systems

3000 Skyline Drive
Mesquite, TX 75149

USA

Phone - 800-526-7819
Fax - 888-315-5182

Outside
U.S.A.: Refer to our Web site below for Serv ice and Suppor tinotherreg io nsof

the world

Web: http://power.tycoel ectr onics.co m/