LTspice Getting Started Guide
Copyright © 2007 Linear Technology. All rights reserved. Why Use LTspice?
Stable SPICE circuit simulation with Unlimited number of nodes Schematic/symbol editor OverOver 1100 1100 macromodels macromodels of of Linear Technology products Waveform viewer Linear Technology products 500+500+ SMPS SMPS Library of passive devices Fast simulation of switching mode power supplies Steady state detection Turn on transient Step response Efficiency / power computations Advanced analysis and simulation options Not covered in this presentation Outperforms pay-for options LTspiceLTspice is is also also a a great great schematic schematic capture capture
LTspice Getting Started Guide 2 How Do I Get LTspice? Go to http://www.linear.com Select “Design Support” and then “Design Simulation” Follow the instruction to install
LTspice Getting Started Guide 3 How Do I Get Started Using LTspice? How Do I Get Started using LTspice?
1. Use one of the 100’s demo circuit available on linear.com Designed and Reviewed by Factory Apps Group 2. Use a pre-drafted test fixture (JIG) Provides a good starting point Used in testing models during development 3. Use the graphic editor to create your own design using the macro models provided LTspice contains models for most LTC power devices
YouYou can can also also check check out out LTspice LTspice capab capabilitiesilities using using the the education education examples examples availableavailable on on C:\Program C:\Program Files\LT Files\LTC\SwCADIII\examples\EducationalC\SwCADIII\examples\Educational
LTspice Getting Started Guide 5 How Do I Get Started using LTspice?
1. Use one of the 100’s demo circuit available on linear.com Designed and Reviewed by Factory Apps Group 2. Use a pre-drafted test fixture (JIG) Provides a good starting point Used in testing models during development 3. Use the graphic editor to create your own design using the macro models provided LTspice contains models for most LTC power devices
LTspice Getting Started Guide 6 Demo Circuits on linear.com
Download LTspice
Download Demo Circuit
LTspice Getting Started Guide 7 Demo Circuit
9 Designed and Reviewed by Factory Apps Group It remains the customer's responsibility to verify proper and reliable operation in the actual application Component substitution and printed circuit board layout may significantly affect circuit performance or reliability
WhatWhat if if I Icannot cannot find find a a demo demo circuit? circuit?
LTspice Getting Started Guide 8 How Do I Get Started using LTspice?
1. Use one of the 100’s demo circuit available on linear.com Designed and Reviewed by Factory Apps Group 2. Use a pre-drafted test fixture (JIG) Provides a good starting point Used in testing models during development 3. Use the graphic editor to create your own design using the macro models provided LTspice contains models for most LTC power devices
LTspice Getting Started Guide 9 Start with a New Schematic
Select File and New Schematic Will open up a black layout screen
LTspice Getting Started Guide 10 Add a Component
Use Add a Component or F2
Take a moment to review all the components!
LTspice Getting Started Guide 11 Selecting Model & Opening Test Fixture
1. Use the “root” part to search for the model i.e. 3411 2. Select “Open this macromodel’s test fixture
2. Select
1. Enter 3411
LTspice Getting Started Guide 12 Pre-Drafted Test Fixture
Provides a good starting point Used in testing models during development
ItIt remains remains the the customer's customer's res responsibilityponsibility to to verify verify proper proper andand reliable reliable operation operation in in the the actual actual application application
PrintedPrinted circuit circuit board board layout layout may may significantly significantly affect affect circuitcircuit performance performance or or reliability reliability
LTspice Getting Started Guide 13 How Do I Get Started using LTspice?
1. Use one of the 100’s demo circuit available on linear.com Designed and Reviewed by Factory Apps Group 2. Use a pre-drafted test fixture (JIG) Provides a good starting point Used in testing models during development 3. Use the graphic editor to create your own design using the macro models provided LTspice contains models for most LTC power devices
LTspice Getting Started Guide 14 Use the Graphic Editor to Create Your Own Design
Select the Model Also Great for drawing schematics Use the menu to design you circuit for customers
= Custom Design
Additional Components Like Sources & Loads
LTspice Getting Started Guide 15 Schematic Editing
Place Circuit Element Place Diode Place Inductor Place Capacitor Place Resistor Label Node Place Ground Draw Wire
Zoom In Move Pan Drag Zoom Out Undo Autoscale Redo Delete Rotate Duplicate Mirror Paste b/t Schematics Place Comment Find Place SPICE directive
LTspice Getting Started Guide 16 Editing Components
Components’ attributes can be edited by pointing at the component with the mouse and right clicking
YouYou can can also also edit edit the the visible visible attribut attributee and and label label by by pointing pointing at at the the text text withwith the the mouse mouse and and then then right right clicking clicking MouseMouse cursor cursor will will turn turn into into a a text text caret caret
LTspice Getting Started Guide 17 Component Database Components such as Resistors, capacitors, inductors, diodes, Bipolar transistors, MOSFET transistors, JFET transistors Independent voltage and current sources can access a database of know devices
LTspice Getting Started Guide 18 Test Fixture Shortcut with LT Macromodels
Place the mouse over the LT macromodel’s symbol Hold down the control key, and click the right mouse button A dialog box will appear that will allow you to Open the test fixture Go to Linear website for the datasheet
LTspice Getting Started Guide 19 How Do You Run and Probe a Circuit in LTspice? Running Demo Circuit
RunRun
Select run “Running Man” logo on menu
LTspice Getting Started Guide 21 Waveform Viewer
LTspice has an integrated waveform viewer 1. Plot the voltage on any wire by simply point and click
Voltage probe cursor 2. Plot the current through any component with two connections by clicking on the body of the component R, C, L Current probe cursor Convention of positive current is in the direction into the pin
LTspice Getting Started Guide 22 Probing a Demo Circuit
ClickClick Here Here forfor Input Input WaveformWaveform
ClickClick Here Here forfor Output Output WaveformWaveform
All Demo Circuits have INs and OUTs clearly labeled to help you quickly select them Select the waveform of a node by clicking on IN and OUT
LTspice Getting Started Guide 23 Zooming In and Out on a Waveform
Using the mouse to zoom in and out Drag a box about the region you wish to see drawn larger Right click and select “Zoom to Fit” to zoom back
LTspice Getting Started Guide 24 Measuring V, I and Time in the Waveform
1. Drag a box about the region you wish to measure Hold the left click down 2. View the lower left hand side of the screen 3. Shrink your box before you let go of the left mouse click or use the undo command on top to resize
LTspice Getting Started Guide 25 Voltage Differences Across Nodes Click on one node and drag the mouse to another node Red voltage probe at the first node Black probe on the second Will provide differentially plot of the voltages
LTspice Getting Started Guide 26 Average/RMS Calculations
Average & RMS Current or Voltage Control - left click the I or V trace label in the waveform view
LTspice Getting Started Guide 27 Instantaneous & Average Power Dissipation
Instantaneous Power Dissipation Hold down the Alt key and left click on the symbol of the component Plotted in units of Watts
Average Power Dissipation Control - left click the power Dissipation trace label in the waveform view
LTspice Getting Started Guide 28 Generating a BOM and Efficiency Report BOM
Under View select Bill of Material Displayed on Diagram Paste to Clipboard
LTspice Getting Started Guide 30 Computing Efficiency To compute efficiency of SMPS circuits: Check the "Stop simulating if steady state is detected" on the Edit Simulation Command editor Rerun simulation Use the menu command View=>Efficiency Report
AutomaticAutomatic detection detection of of steady steady state state may may not not always always work work – – criteriacriteria for for steady steady state state detection detection may may be be too too strict strict or or too too lenient lenient
LTspice Getting Started Guide 31 Viewing Efficiency Report
LTspice Getting Started Guide 32 Simulate a Transient Response? Current Load and Pulse Function
Your can simulate a load with a Resistor or Current load In particular the Pulse function in a current load is helpful in transient response analysis Steps a current load from one value to another
LTspice Getting Started Guide 34 Edit the Current Load to a Pulse Function
Right click on the current load Select Pulse Modify the Attributes
LTspice Getting Started Guide 35 More Information and Support Reminder to Periodically Sync Release
It is important to sync your release of LTspice once a month to get the latest Software update and bug fix Models Sample circuits and examples
LTspice Getting Started Guide 37 Built-in Help System
Select F1 for help menu
LTspice Getting Started Guide 38 Paper Manual
Download the pdf of the help pages from: http://LTspice.linear.com/software/scad3.pdf
LTspice Getting Started Guide 39 Emailing Support Make sure you’re using the current version with Field sync.
LTspice Getting Started Guide 40 LTspice Support Group
The group has a Files section with additional tutorials, libraries, and examples Visit the user group http://groups.yahoo.com/group/LTspice/ Join LTspice Yahoo Group Email [email protected] Subject=Subscribe
LTspice Getting Started Guide 41