LTspice getting started guide [2011]
2 likes10,187 views
The LTspice IV getting started guide outlines the installation and features of the LTspice IV circuit simulation software, highlighting its benefits such as stable circuit simulations, a vast library of passive devices, and advanced analysis options. Users are instructed on how to download the software, access demo circuits, and utilize the schematic editor to create designs with macromodels for Linear Technology products. Additional sections cover editing circuit elements, running simulations, viewing results, and tips for configuring loads and transformers.
LTspice getting started guide [2011]
- 1. LTspice IV Getting Started GuideLTspice IV Getting Started Guide Copyright © 2011 Linear Technology. All rights reserved.
- 2. 2 Benefits of Using LTspice IVBenefits of Using LTspice IV Stable SPICE circuit simulation with Unlimited number of nodes Outperforms pay-for options Unlimited number of nodes Schematic/symbol editor Waveform viewer LTspice is also a great schematic capture Library of passive devices Fast simulation of switching mode power supplies (SMPS) Steady state detectionSteady state detection Turn on transient Step response Over 1100 macromodels of Linear Technology products 500+ SMPSp p Efficiency / power computations Advanced analysis and simulation options © 2011 Linear Technology Not covered in this presentation
- 3. 3 How Do You Get LTspice IVHow Do You Get LTspice IV Go to http://www.linear.com/LTspice Left click on Download LTspice IV Register for a new MyLinear account to receive updates if you have not done so already © 2011 Linear Technology
- 4. Getting Started Copyright © 2011 Linear Technology. All rights reserved.
- 5. 5 Getting Started using LTspice IVGetting Started using LTspice IV Use one of the 100s of demo circuits available on linear.com Reviewed by Linear Technology’s Factory Applications GroupReviewed by Linear Technology s Factory Applications Group Use a pre-drafted test fixture (JIG) Provides a good starting pointProvides a good starting point Use the schematic editor to create your own design LTspice contains macromodels for most LTC power devicesp p © 2011 Linear Technology
- 6. 6 Demo Circuits on linear comDemo Circuits on linear.com Go to http://www.linear.com Enter root part number in the searchte oot pa t u be t e sea c box (e.g. 3411) Select Simulate Tab on the left side Follo the instr ctions pro idedFollow the instructions provided If you do not find a demo circuit of interest, use a pre-drafted test Download LTspice , p fixture – covered next Download LTspice Download Demo Circuit C l li f d i i il bl © 2011 Linear Technology Complete list of demo circuits available at www.linear.com/democircuits
- 7. 7 Demo CircuitDemo Circuit Designed and Reviewed by Factory Apps Group To run a demo circuit jump to the Run and Probe aRun and Probe a Circuit in LTspiceCircuit in LTspice section What if I cannot find a demo circuit?a demo circuit? It remains the customer's responsibility to verify proper and reliable operation in the actual application © 2011 Linear Technology Printed circuit board layout may significantly affect circuit performance or reliability
- 8. 8 Getting Started using LTspice IVGetting Started using LTspice IV Use one of the 100s of demo circuits available on linear.com Reviewed by Linear Technology’s Factory Applications GroupReviewed by Linear Technology s Factory Applications Group Use a pre-drafted test fixture (JIG) Provides a good starting pointProvides a good starting point Use the schematic editor to create your own design LTspice contains macromodels for most LTC power devicesp p © 2011 Linear Technology
- 9. 9 Pre-Drafted Test Fixture (JIG)Pre Drafted Test Fixture (JIG) Used for testing models during development Provides a draft starting pointProvides a draft starting point Not reviewed by Linear Technology’s factory applications team It remains the customer's responsibility to verify proper and reliable operation in the actual application © 2011 Linear Technology Printed circuit board layout may significantly affect circuit performance or reliability
- 10. 10 Start with a New Schematic New Schematic Start with a New Schematic Left click on the New Schematic symbol in the Schematic Editor Toolbar © 2011 Linear Technology
- 11. 11 Add a Macromodel & Opening Test FixtureAdd a Macromodel & Opening Test Fixture Add Component Left click on the Component symbol in the Schematic Editor Toolbar E t “ t” t t h f th d lEnter “root” part to search for the model (e.g. 3411) Left click on Open this macromodel’s test fixturetest fixture To run a test fixture, jump to the Run andRun and Probe a Circuit in LTspiceProbe a Circuit in LTspice section © 2011 Linear Technology pp
- 12. 12 Getting Started using LTspice IVGetting Started using LTspice IV Use one of the 100s of demo circuits available on linear.com Reviewed by Linear Technology’s Factory Applications GroupReviewed by Linear Technology s Factory Applications Group Use a pre-drafted test fixture (JIG) Provides a good starting pointProvides a good starting point Use the schematic editor to create your own design LTspice contains macromodels for most LTC power devicesp p © 2011 Linear Technology
- 13. Draft a Design Using the Schematic Editor Copyright © 2011 Linear Technology. All rights reserved.
- 14. 14 Start with a New Schematic New Schematic Start with a New Schematic Left click on the New Schematic symbol in the Schematic Editor Toolbar LTspice is also a great schematic captureschematic capture © 2011 Linear Technology
- 15. 15 Add a Linear Technology MacromodelAdd a Linear Technology Macromodel Add Component Left click on the Component symbol in the Schematic Editor Toolbar Enter “root” part to search for the model (e.g. 3411) Left click on OK © 2011 Linear Technology
- 16. 16 Getting the Latest DatasheetGetting the Latest Datasheet Use the macromodel’s shortcuts to download the Datasheet as a reference for your designy g Hold Ctrl key and right click (Ctrl – right click) over the LT macromodel’s symbol Left click on Go to Linear website for datasheet on the dialogLeft click on Go to Linear website for datasheet on the dialog box that appears You can also open the macromodel's test fixture as a draft starting pointYou can also open the macromodel s test fixture as a draft starting point © 2011 Linear Technology
- 17. 17 Adding Circuit Elements Pl Di dAdding Circuit Elements Rotate Mirror Place Diode Place Inductor Place Capacitor Place Resistor Left click on the desired component in the Schematic Editor Toolbar Left click on Rotate or Mirror to adjust orientation Alternate you can also use Ctrl – R and Ctrl – M key shortcuts Move the mouse to the position you want to place it To cancel or quit a component type, click the right mouse button Move the mouse to the position you want to place it Left click to place it © 2011 Linear Technology click the right mouse button
- 18. 18 Adding Sources Loads & Additional Circuit ElementsAdding Sources, Loads & Additional Circuit Elements Left click on the Component symbol in the Schematic Editor Toolbar Search directory structure for desired circuit element (e.g. load and voltage) Left click on OK Move the mouse to the position you want to place it Left click to place it © 2011 Linear Technology Additional Circuit Elements Like Sources and Loads
- 19. 19 Highlights of Additional Circuit ElementsHighlights of Additional Circuit Elements Left click on the Component symbol in the Schematic Editor Toolbar for a directory of additional circuit elements: Arbitrary behavioral source Voltage dependent voltage Current dependent current Lossy transmission line Bipolar transistor Voltage controlled switchCurrent dependent current Voltage dependent current Current dependent voltage Independent current source g Lossless transmission line Uniform RC-line Independent voltage sourceIndependent current source JFET transistor Mutual inductance Independent voltage source Current controlled switch Subcircuit MOSFET transistor MESFET transistor …many more © 2011 Linear Technology
- 20. 20 Drawing Lines and Labeling NodesDrawing Lines and Labeling Nodes Draw Wire Place Ground Do not forget to place a Lines Place Ground Label Node g p ground in your design, it is required for simulation! Left click on the Draw Wire in the Schematic Editor Toolbar Left click a blue box (terminal) Define the line’s path with a left click over intermediate pointsp p Left click on another blue box (terminal) © 2011 Linear Technology
- 21. 21 Editing Circuit Elements DeleteEditing Circuit Elements Duplicate Move Dragag Undo Redo Left click on the desired editing option To organize your layout use the Drag option to move circuit g p Left click on the circuit element To organize your layout, use the Drag option to move circuit elements around and to adjust lines between terminals © 2011 Linear Technology
- 22. 22 Editing Circuit Elements AttributesEditing Circuit Elements Attributes Right click on the component symbol to modify attributes Right click on the text next to the component to edit theRight click on the text next to the component to edit the visible attribute and label Pointer will turn into a text caret © 2011 Linear Technology
- 23. 23 Use Labels to Specify Units in Circuit Elements AttributesUse Labels to Specify Units in Circuit Elements Attributes K = k = kilo = 103 MEG = meg = 106 m = M = milli = 10-3 u = U = micro = 10-6g G = g = giga = 109 T = t = terra = 1012 n = N = nano = 10-9 p = P = pico = 10-12 f = F = femto = 10-15f = F = femto = 10 15 ImportantImportant Use MEG to specify 106, not M Enter 1 for 1 Farad, not 1F © 2011 Linear Technology
- 24. 24 Circuit Elements DatabaseCircuit Elements Database Some components have an available database of manufacturers’ attributes Resistors, capacitors, inductors, diodes, Bipolar transistors, MOSFET transistors, JFET transistors Independent voltage and current sources To configure a component to a manufacture’s attributes Right click on the component symbol Left click on Select… or Pick New… Left click on a selected deviceLeft click on a selected device Left click on OK © 2011 Linear Technology
- 25. 25 Editing Voltage Sources and LoadsEditing Voltage Sources and Loads Voltage Source Right click the voltageg g symbol Enter DC voltage value and (optional) Series Resistance Left click on OK Load (current) Right click on the loadRight click on the load symbol Enter DC current value Left click on OKLeft click on OK © 2011 Linear Technology
- 26. 26 Summary of Schematic Editor ToolbarSummary of Schematic Editor Toolbar Place Circuit Element Place Diode Place InductorPlace Inductor Place Capacitor Place Resistor Label Node Place Ground Draw Wire Move DragDrag Undo Redo Rotate Mirror Delete Duplicate © 2011 Linear Technology Mirror Place Comment Place SPICE directive p Paste b/t Schematics Find
- 27. Run and Probe a Circuit Copyright © 2011 Linear Technology. All rights reserved.
- 28. 28 Simulation CommandsSimulation Commands To run a simulation, specify the type of analysis to be performedp There are six different types of analyses: Transient analysis Small signal AC DC sweep Noise More information on simulation and dot commands are available in LTspice IV User Guide Noise DC transfer function DC operating point Simulation commands are placed on the schematic as text Called dot commands © 2011 Linear Technology
- 29. 29 Editing Simulation CommandsEditing Simulation Commands Left click on Simulation menu Left click on Edit Simulation Cmd Demo Circuits and Test Fixtures have predefined Simulations C dLeft click on Edit Simulation Cmd As a starting point in a simulation Left click on Transient tab Commands Enter a Stop Time You may need to adjust this again lateragain later Select OK © 2011 Linear Technology
- 30. 30 Running a CircuitRunning a Circuit Run If model is not found please Sync Release © 2011 Linear Technology p y under Help menu to update LTspice
- 31. 31 Probing a Circuit & Waveform ViewerProbing a Circuit & Waveform Viewer Left click on any wire to plot the voltage on the waveform viewer Voltage probe cursor Left click on the body of the component to plot the current on the waveform g p to plot the current on the waveform viewer Convention of positive current is inp the direction into the pin © 2011 Linear Technology Current probe cursor
- 32. 32 Probing a Demo Circuit and Test FixtureProbing a Demo Circuit and Test Fixture Demo Circuits and Test Fixtures have INs and OUTs clearly labeled to help you quickly select themp y q y To view the waveform left click on IN and OUT L ft Cli kLeft Click Left Click Here for Output Waveform Left Click Here for Input Waveform WaveformWaveform © 2011 Linear Technology
- 33. 33 Voltage Differences Across NodesVoltage Differences Across Nodes Left click and hold on one node and drag the mouseg to another node Red voltage probe at the first nodenode Black probe on the second Differential voltages are displayed in the waveform viewerviewer © 2011 Linear Technology
- 34. 34 Plot PlanesPlot Planes Multiple plot panes can be displayed on one window to allow better separation between traces permitting different traces to be i d d tl t l dindependently autoscaled Right click in the waveform pane Select Add Plot Pane Left click and hold to drag a label to a new plot pane © 2011 Linear Technology
- 35. 35 Zooming In and Out in the Waveform ViewerZooming In and Out in the Waveform Viewer To zoom in Left click and hold as youLeft click and hold as you drag a box about the region you wish to zoom in then releaserelease To zoom out Right click and select Zoom to Fit or Zoom Back Zoom In Pan © 2011 Linear Technology Pan Zoom Out Autoscale
- 36. 36 Measuring VRi l IRi l and Time (Frequency)Measuring VRipple, IRipple and Time (Frequency) Drag a box about the region you wish to measure (peak to peak over a period) Left click and hold to drag a box over the portion of interest View the lower left hand side of the screen To avoid resizing shrink your box before you let go of the left mouseTo avoid resizing, shrink your box before you let go of the left mouse click or use the Undo command in the Edit menu T i SMPS lt i l illTo view SMPS voltage ripple you will need to zoom into a narrow section since waveform is initially compressed to full rangeco p essed to u a ge © 2011 Linear Technology
- 37. 37 Average/RMS Current or Voltage CalculationsAverage/RMS Current or Voltage Calculations Hold down Ctrl and left click on the I or V trace label in the waveform viewer © 2011 Linear Technology
- 38. 38 Instantaneous & Average Power DissipationInstantaneous & Average Power Dissipation Instantaneous Power Dissipation Hold down the ALT key andy left click on the symbol of the component Pointer will change to a thermometer Plotted in units of Watts Average Power Dissipation Hold down the Ctrl key and left click on the trace labelleft click on the trace label power dissipation waveform © 2011 Linear Technology
- 39. Generating a BOM and Efficiency Report Copyright © 2011 Linear Technology. All rights reserved.
- 40. 40 Bill of Materials (BOM)Bill of Materials (BOM) Left click on View menu Left click on Bill of MaterialsLeft click on Bill of Materials © 2011 Linear Technology
- 41. 41 Computing Efficiency of SMPS CircuitsComputing Efficiency of SMPS Circuits Left click on Simulate menu Left click on Edit Simulation CmdLeft click on Edit Simulation Cmd Left click on Stop simulating if steady state is detected Automatically detect the steady state by checking the internaly y y g state of the macromodels Rerun simulation Automatic detection of steady state may not work – steady state detection may be too strict or lenient © 2011 Linear Technology
- 42. 42 Viewing Efficiency ReportViewing Efficiency Report Left click on Simulate menu Left click on Efficiency ReportLeft click on Efficiency Report © 2011 Linear Technology
- 43. Simulate a Transient Response in a SMPS Advanced Topic Copyright © 2011 Linear Technology. All rights reserved.
- 44. 44 Use a Pulsed Function as a Transient Response LoadUse a Pulsed Function as a Transient Response Load Insert a current source load Left click on the Component symbol in the Schematic Editor Toolbarp y Select load (or load2) circuit element and configure as pulsed Left click on OK Configure load as a pulsed function (covered next)Configure load as a pulsed function (covered next) Steps current from initial to pulsed value and back Run and review results © 2011 Linear Technology
- 45. 45 Configuring Load as a Pulse FunctionConfiguring Load as a Pulse Function Right click on the load (or load2) component Select Pulse Modify the Attributes I1 = Initial value I2 = Pulsed ValueI2 = Pulsed Value Tdelay = Delay Tr = Rise time Tf = Fall time Ton = On time Tperiod = Period Tdelay needs to be adequate so that the device is in steady state and out Ncycles = Number of cycles Omit for free running the device is in steady state and out of startup before the load step occurs You may need to un click Stop simulating if steady state is detected © 2011 Linear Technology You may need to un-click Stop simulating if steady state is detected and specify an end time in Edit Simulation Cmd under the Simulate menu
- 46. Simulate a Transformer Advanced Topic Copyright © 2011 Linear Technology. All rights reserved.
- 47. 47 Simulating a TransformerSimulating a Transformer Draw each winding of the transformer as an individual inductor Couple inductors with a mutual inductance statement Add a SPICE directive of the form K1 L1 L2 L3 ... 1 to the schematic Left Click on Edit then SPICE Directive Inductors in a mutual inductance will be drawn with a phasing dotInductors in a mutual inductance will be drawn with a phasing dot Start initially with a mutual coupling coefficient equal to 1 K statement couplingp g the windings For more information check out LTC1871 d i it d 23 24 f S t b 1:3 turns ration gives Note: winding inductance ratio is demo circuit and page 23-24 of September 2006 LT Magazine at www.linear.com © 2011 Linear Technology g a 1:9 inductance ratio g the square of the turns ratio
- 48. Additional Information and Support Copyright © 2011 Linear Technology. All rights reserved.
- 49. 49 Reminder to Periodically Sync ReleaseReminder to Periodically Sync Release Update your release of LTspice to get the latest Software updatesSoftware updates Models and examples Sign up for Linear Insider via MyLinear (www.linear.com) for email news and updatesemail news and updates List of changes are available in the changelog.txt that is located in © 2011 Linear Technology List of changes are available in the changelog.txt that is located in your LTspice root directory (C:Program FilesLTCSwCADIII)
- 50. 50 Built-in Help SystemBuilt in Help System Left Click on Help menu and then Help Topics To print out a hardcopy download user guide at © 2011 Linear Technology To print out a hardcopy, download user guide at http://LTspice.linear.com/software/scad3.pdfhttp://LTspice.linear.com/software/scad3.pdf
- 51. 51 Emailing Comments and Signing up for Linear InsiderEmailing Comments and Signing up for Linear Insider © 2011 Linear Technology
- 52. 52 Customer SupportCustomer Support Linear Technology customers can obtain support by Calling your local field applications engineerCalling your local field applications engineer http://www.linear.com/contact/ Calling +1 (408) 432 – 1900 for factory application support Additional support (not related to Linear Technology circuits or models support) Built-in help topics & User ManualBuilt in help topics & User Manual Independent LTspice users’ group (search messages) Simulation with the supplied models is fully supported All bug reports are appreciated and will be resolved © 2011 Linear Technology g p pp
- 53. 53 Independent LTspice Users’ GroupIndependent LTspice Users Group The group has a section of files and messages with additional tutorials, libraries, and examples, , p http://groups.yahoo.com/group/LTspice/ Join LTspice Users’ Group Email LTspice-subscribe@yahoogroups.com Subject=Subscribe © 2011 Linear Technology