So my experience isn't good enough to give you anything close to a survey of them. The solver combats this by Gmin and/or source stepping (more on this later). #LTspice #TripleTech #TransientAnalysisDc RC LTspice Transient Analysis . or "a current source in series of a 1 Ohm" for "equation-type" solving purposes. Does it take a long time before, or after, the plot window appears? It never makes sense to add them for any simulation that takes under a minute or two. It is a .TRAN analysis, right? You're right, I should have provided a specific circuit, but since it had happened on a variety of cases I thought there probably was a single, common cause to all of them. Default = 0. Electrical Engineering Stack Exchange is a question and answer site for electronics and electrical engineering professionals, students, and enthusiasts. If it fails to converge again and doesnt meet the tolerance requirements it backs up and tries again, which results in the simulation failing to solve for new timesteps. About SPICE: Should I use transient analysis or DC linear analysis? Whenever possible, I try to arrange a model so the capacitors do double duty, that is to both aid transient convergence and to provide some direct function (e.g., an opamp pole). I might have gotten lucky. Check device models to see if they provide unrealistic conductances. \$\endgroup\$ - So, by starting from a known linear solution (i.e., zero ) the solver can bootstrap itself up to the normal operating point by gradually ramping up all the sources. Now, it is set to perform transient analysis for 10msec. MathJax reference. Paul Savin wrote, "I ask you, is it allowed to ask for help on completing a circuit?". To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Are you sure you wish to repost this message? This . Splitting a very nonlinear element into several pieces across several nodes can sometimes dilute the problematic behavior to the point where the solver no longer gets hung up on one very bad element. Of course this assumes you do not need the initial data Of course, it does not matter if you enter "0.01" instead of "10m" without using auxiliary units. Stack Exchange network consists of 181 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. I'm not very experienced with LTspice, and this is the first time I use the XOR-gate. Auxiliary unit of LTspice. Start LTspice and select New Schematic from the File Menu. I'm currently using LTspice, and I have a problem with it "never" finishing calculating a certain circuit. Do assets (from the asset pallet on State[mine/mint]) have an existential deposit? The real world isn't like that but LT spice is, unless you watch the parasitics. LTspice can use auxiliary units other than "m" as shown in the following table. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Perform a transient analysis. Components can be selected in two ways. MOSFETs have more convergence problems that BJTs, as MOSFETs have a self-conductance of zero at DC for their gates. exhibit linear behavior locally around zero (all junctions are off and other nonlinearities are, by definition, operating with small signals). Increase the allowed tolerance from 0.0001 to 0.003 for the convergence criteria. What should I gain out of second year classes? Apr 21, 2018. Well, at "stock" setup (same as downloaded model), it takes my AMD A10-7850K 13,4 seconds to finish. But the most important thing needed to answer your question, is the full schematic (.asc), and models and symbols that didn't come with LTspice -- everything needed to run the simulation. Site design / logo 2022 Stack Exchange Inc; user contributions licensed under CC BY-SA. .options reltol=0.003 => Increase the allowed tolerance from 0.0001 to 0.003 for the This part is "e" in the LTspice component library. How to trace down why LTSpice simulation is slow? Do solar panels act as an electrical load on the sun? In theory each successful step along the way allows linearly extrapolating an almost perfect set of initial conditions for solving the succeeding nearby step. that all node voltages and branch currents are zero as well). If the next time step is not converging it 'backs up' and tries again, to explain this in detail would require a knowledge of numerical methods (of which I only understand the basics). Is `0.0.0.0/1` a valid IP address? How can I force LTspice to redraw a plot during a long simulation? A lot of times adding pFs and Mohms are fine because those values are close to that of air or from plane to plane in FR4. I find that when I change the circuit configuration adding / deleting a connection or components and ask for a new run, I have high chances that it will freeze in the first steps. To learn more, see our tips on writing great answers. I always use either "a voltage source in series of a 1G Ohm" Never use a strict voltage source if you can avoid it (the one exception is a zero volt source used for current sensing). rev2022.11.16.43035. All of these settings changes trade off accuracy for speed. It was faulty wiring in the XOR-gate because of a misunderstanding. harmonic balance and transient solvers in RF CAD softwares like ADS and MWOffice, as well as electromagnetic and FEM solvers. Undoubtedly you have declared an input to the circuit and most likely some sort of load for the sake of LTspice. Of course, it does not matter if you enter "0.01" instead of "10m" without using auxiliary units. Also, bear in mind that a simulated circuit may have several numerically valid dc solutions, only one of which usually corresponds to the real circuit's natural solution. I have seen Spice get stuck with a third-party model of a 1n4007 where just replacing that with the standard Diode model (the one built-into the STD lib) will make the simulation run infinitely faster. Using LTSpice LTSpice is a software for circuit analysis. The pseudo transient analysis issue happens only when I replace the OR gates (A5, A6, A9, A11) in favour of NOR gates inside the ZD one-shot circuit blocks. Relax them and see if that helps. Also, there is no .tran signal in the sources (at least nothing visible), they are set to .ac analysis: either use a time domain signal for .tran, or switch to an .ac card. When the migration is complete, you will access your Teams at stackoverflowteams.com, and they will no longer appear in the left sidebar on stackoverflow.com. Asking for help, clarification, or responding to other answers. Normally, LTspice transient analysis starts at time = 0. When the direct Newton method fails the simulation goes through the process of GMIN stepping and then if that fails, it tries source stepping. How can I attach Harbor Freight blue puck lights to mountain bike for front lights? How friendly is immigration at PIT airport? I connected those nodes to ground via 10Meg resistors and now it works fine. How to license open source software with a closed source component? That gives you the simulation progress. And although you occasionally encounter this problem, it may be that each time it is for a different reason requiring a different explanation. Stack Overflow for Teams is moving to its own domain! And that is asking way, way too much. You must know something about the signal to set-up the correct parameters for a transient analysis. It is as simple as using the 'list' AC Analysis option in the simulation command, and specifying the frequency at which you want to perform the analysis, in this case, 1MHz: .step oct param C 10p .5n 30. But I was changing the values to get output voltage at 13,8V then changed output capacitor (battery) to 0,1mF, changed input voltage to 19V and simulation time to 50ms. Instead of relaxing RELTOL, try tightening it up in order to avoid bypassing some otherwise "inactive" device in the schematic. It is the aNPC circuit (only one leg) with the 6 gate drivers using GaN transistors. V (stage3_out): 0.00027854 voltage. SPICE settings that generally work with Transient Analysis .options gmin=1e-10 .options abstol=1e-10 . There are many circuit-analysis software available, however I suggest to use LTSpice for the following . Or else just hook up a high valued resistor to ground for such nodes. #3. Does the Inverse Square Law mean that the apparent diameter of an object of same mass has the same gravitational effect? . Speeding software innovation with low-code/no-code tools. I had two capacitors in series, and the node between them was floating. Also, if you are running a transient simulation, try skipping the initial operating point . Stack Overflow for Teams is moving to its own domain! I tried implementing the circuit from your application note in LTspice and it worked (it is here), but: As you can see, the pink trace is roughly twice the frequency of the green one (the input signal), working as expected. Check device models to see if they provide unrealistic conductances. Now, it is set to perform transient analysis for 10msec. It also takes advantage of the fact that most all nonlinear elements (e.g. of transistors and diodes. Connect and share knowledge within a single location that is structured and easy to search. Also reducing the accuracy by changing the values of the parameters on the right such as the Abstol, Volttol, etc. Sometimes I run a simulation and LTSpice stops plotting way before the end of it. Hi everyone, I have a problem with transient simulation on LTSpice. Thanks for contributing an answer to Electrical Engineering Stack Exchange! How to stop a hexcrawl from becoming repetitive? BJTs, of course, don't have that issue. You can edit the .trans simulation command's "Time to start saving data" to delay saving until a later time of interest, thus decreasing your overall simulation time. How to run new .meas commands without having to rerun the whole ltspice simulation? In LTspice, this can be as simple as filling in realistic values for a voltage source's parasitic resistance and capacitance . The only effect on such an expression occurs during source stepping while seeking the dc operating point. It has numerous bugs (like the problems with cursor measurements) and poor support to models and changing them. I have been trying to understand your models of PWM controllers. . Use MathJax to format equations. Use MathJax to format equations. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Heres how. When I've run into this issue, its because I haven't declared my load as an active load. If none of that helps, then just click the "Reset to Default Values" to go back to the . if you're patient, does LTSpice recover, and continue? When was the earliest appearance of Empirical Cumulative Distribution Plots? Thank you for the book as well, it looks like I should give it a read. Chapter 10. t-test where one sample has zero variance? In 2012, why did Toronto Canada lawyers appear in London, before the Judicial Committee of the Privy Council? Instead, you ask us to write a chapter or two -- maybe even a book -- on the topic. I have been using intensively LTSpice in the last week always in the same PC. There is a lot of "black magic" that goes into creating models that do not have discontinuities in their I/V characteristics. Problems come when starting at zero doesn't yield a zero output. Of course this can't work if the models omit the "parasitic" capacitances (and resistance). I won't use it anymore - I prefer the free version of microcap - it has better tools, no bugs that I can find and it's only limitation is the size of the circuit you can simulate (isn't really a problem if you are shrewd). Generally, convergence problems stem from the same underlying cause of an ill-formed matrix, lack of numerical precision, or operating a model outside of its well-defined region. Now back to problems finding the dc operating point. You can add biometric authentication to your webpage. If I remove two of the opamps in the chain . Why does de Villefort ask for a letter from Salvieux and not Saint-Mran? This is fine for low frequencies and dc, but the capacitor is there to aid transient convergence in the face of behavior nonlinear enough to fall outside of the various error tolerance limits (to which the solver responds by reducing the time step). Use MathJax to format equations. Thank you for commenting! Why is it valid to say but not ? I'll add that this is not limited to SPICE solvers. Making statements based on opinion; back them up with references or personal experience. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. @TonyStewartSunnyskyguyEE75 using smaller time steps on transients also does not help. My mistake. This includes: harm to minors, violence or threats, harassment or privacy invasion, impersonation or misrepresentation, fraud or phishing. The key to the source described here is using a resistor as a white noise generator. Set Stop Time ( time for which you want to run the simulation), Saving Time ( time from which you want to start saving your data) and Step Time ( the number of steps to plot on the waveform) Now save the file and go to simulate tab and select Run as shown below. Asking for help, clarification, or responding to other answers. Add a small conductance of 1e10(=10GOhm) parallel to every diode of transistors and diodes. Auxiliary unit of LTspice. How to show opamp noise contribution in LTspice .noise calculation, LTSpice: hand calculation vs simulation - GDS/ro value, Showing to police only a copy of a document with a cross on it reading "not associable with any utility or profile of any entity". The circuit I'm talking about is this frequency doubler. I am puzzled with the necessity of adding the capacitor (with various value) when converting a current to a voltage. Unit (prefix) Unit Multiple; T: tera: 10 12: G: giga: 10 9: Meg: mega . I'll try to explain how this powerful software can be utilized to solve circuit problems quickly and easily. How can I attach Harbor Freight blue puck lights to mountain bike for front lights? Multiplying a trouble point by a unity node voltage (explained later) helps because it tends to tilt the solution trajectory slope closer to the expected path, thereby keeping it locally monotonic so it won't get stuck. So you do yourself no service by failing to provide a specific example. Heres how. What was the last Mac in the obelisk form factor? "5-V(fb)") will go to 5V when all sources are at zero (LTspice actually has extended source stepping to B-sources to address this). Is the portrayal of people of color in Enola Holmes movies historically accurate? Abstol = 1e-012 to 1e-08. They were caused by floating nodes between capacitors in series. Tstop is the duration of the simulation. LTspice uses a solver that is based on convergence. Then, as this unity node is reduced to near zero, anything multiplied by it is also forced to approach zero. You can add biometric authentication to your webpage. The question is why LTSpice? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Subject of the new topic: Tony is right. These types of expressions can be multiplied by the unity node raised to whatever power required to make them behave. Is it to help the convergence or to implement the pole of op amp? and the list is very long. http://ltwiki.org/index.php?title=Convergence_problems%3F&oldid=1207. At really small time steps, only the capacitances will matter and, since capacitances are linear, the circuit will converge and the simulator will be able to get past the nonlinear behavior. In order to get good transient convergence, a good model should, as much as possible, contain elements with only voltage inputs and only current outputs (Norton equivalents should be used to produce voltage sources). Why do many officials in Russia and Ukraine often prefer to speak of "the Russian Federation" rather than more simply "Russia"? Reduce the Amount of Transient Analysis Data. Asking for help, clarification, or responding to other answers. @carllacan A floating node between capacitors is a very very common problem. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. As good as it is, LTspice is not magic, and the old maxim "garbage in - garbage out" still applies. Also, Spice assumes BJTs are, Many Spice implementations (LTspice included) offer different solution methods. How can I make combination weapons widespread in my world? The only voltage sources should be zero volt sources used for current sensing. I am running a simulation on LTSpice. I undid them as soon I saw your schematic Renan, and it works perfectly now. Same Arabic phrase encoding into two different urls, why? But it is nothing like that, at all. rev2022.11.16.43035. LTSpice, in my opinion, is starting to be a disservice to the EE industry. Insufficient charge storage leads to switching times that approach zero time and this can result in a serious slow-down either at the beginning, or else later during simulation. I forgot all about it and therefore didn't try to undo them when I stumbled upon problems. You might find that one works where the other works more poorly. And all of the better ones (I do NOT consider MULTISIM worth a darn, but I haven't used it in years now so perhaps it is better today) have enough problem areas that no one of them seems "the way to go.". MathJax reference. You seem to use a BI current source in series of a capacitor very often. How does a Baptist church handle a believer who was already baptized as an infant and confirmed as a youth? If you need to export your simulation with a fixed timestep, the only option LTspice provides is to use the .wave command -- see the help for LTspice > Dot Commands > .WAVE. Browse other questions tagged, Start here for a quick overview of the site, Detailed answers to any questions you might have, Discuss the workings and policies of this site, Learn more about Stack Overflow the company. Connect and share knowledge within a single location that is structured and easy to search. I did also try adding a capacitor after I read your models. To follow these rules means that p/n junctions (and other nonlinear element nodes) should never be without some series resistance and some parallel capacitance. Are you sure you wish to delete this message from the message archives of LTspice@groups.io? 1. Of course, it does not matter if you enter "0.01" instead of "10m" without using auxiliary units. Is it bad to finish your talk early at conferences? It would be a lot better if you'd provide a specific case. But none of them I have experienced are free of problem areas. It only takes a minute to sign up. .options gmin=1e-10 => Add a small conductance of 1e10(=10GOhm) parallel to every diode If it says Defcon 1 then it is having convergence problems and is trying other slower methods to try to make the circuit converge. Difficulties can also occur when ramping up through sharp corners or discontinuities in a nonlinear device's characteristic. Perhaps these thoughts will help. How to stop a hexcrawl from becoming repetitive? Why the difference between double and electric bass fingering? Never larger than 0.003! Behavioral expressions with node voltages in their denominators such that when the sources go to zero, the expressions blow up (something gone small / something gone to zero => infinity) can be especially troublesome. Transient analyses always start at time equal to . Portable Object-Oriented WC (Linux Utility word Count) C++ 20, Counts Lines, Words Bytes. Not sure how exactly is that causing the problem, but reducing the timestep solves it, so thank you very much. It can't be stressed enough that stiff voltage sources (especially nonlinear behavioral types) are problematic because, unlike current sources and/or resistors, they will not yield to capacitances at small time steps during convergence difficulties in a transient analysis. If an ac analysis produces wildly unexpected results, it may be due to an improper dc solution. If the time steps go small enough, the capacitor will dominate the I/V behavior of any finite impedance (hence, the need to use current sources with parallel resistors rather than voltage sources). Plenty of convergence problems and solutions in other circuit solvers, i.e. #1. Do solar panels act as an electrical load on the sun? Please note that the book isn't about LTspice; instead it is about pretty much all Spice programs. This page was last edited on 1 October 2013, at 13:30. Stack Overflow for Teams is moving to its own domain! LTSpice is really clunky too. Of course this assumes you do not need the initial data points, which . Look into the .OPTIONS for LTspice: ABSTOL and RELTOL. Toilet supply line cannot be screwed to toilet when installing water gun, "Cropping" the resulting shared secret from ECDH, What would Betelgeuse look like from Earth if it was at the edge of the Solar System, tikz matrix: width of a column used as spacer. Cause for Artemis Spacecraft bumpy surface. I'll start with simple transient analysis. The one I encountered most recently started happening when I added resistive and inductive losses to a mains voltage, if I used an inductance over 1 pH. The machine is based on an FX8350 with ram and given the significant . Hopefully, I addressed enough to help someone get by without needing to apprehend how it applies broadly to an entire academic class of problems. .ac list . @Shamtam Thanks for the kind word. Heres how. Does anybody know a solution to this problem? For example, a behavioral error amp with a numeric reference voltage in a difference equation (i.e. And all of them have problems similar to what you describe. Both of these methods truncate numerical errors in the solver and reduce the time it needs to solve. Is there any legal recourse against unauthorized usage of a private repeater in the USA? For .TRAN simulations (and those are not the only functions where problems arise), let me list a few thoughts in no particular order that apply to any Spice program, including LTspice: I've only used a few different Spice programs in the past. When I get those errors, it is usually because the SPICE model from the manufacturer is wrong or broken, or that your SPICE settings are wrong (open the LTspice's Control Panel and click Reset on the SPICE tab). Could anyone advise about the pseudo transient analysis issue in my GFSK demodulator circuit ? LTspice offers an elegant solution for holding frequency constant and performing small signal analysis over a varying parameter. I think this violates the Terms of Service. I know. Could you explain what's the difference between grounding those nodes via a big resistor and grounding them via a small capacitor? In fact, there is a chapter on this topic included in "The Spice Book," by Andrei Vladimirescu. (I know exactly ONE person who I consider to be "always well-placed to solve any convergence problem" because I've never yet seen a case where he wasn't quickly able to identify exactly where to add something to make Spice work well on the problem.). Making statements based on opinion; back them up with references or personal experience. use a strict voltage source if you can avoid it (the one exception is a zero volt source used for current sensing). Hi, I am doing an LTSpice simulation of some opamps but I have the transient analysis stuck at 10.9% for several hours. The voltage noise produced by the resistor is the input to a voltage-dependent voltage source. Hi Andy, for the slowness problem I really solved it by adding the command ".options cshunt = 1e-15". Whenever the simulator reduces the time step, it is because of nonlinear circuit behavior. .options abstol=1e-10 => Increase the allowed tolerance from 1e-12 to 1e-10 for the .options cshunt=1e-15 => Capacitance added from each node to ground. Note: pseudo transient analysis issue means that the LTSpice simulator is stucked with running pseudo transient analysis forever without any output waveform results. You can apply it in cases like this. convergence criteria. @TonyStewartSunnyskyguyEE75 Why "the schematic in fig 4 shows the wrong pulse polarity" ? Select "Transient" and enter "10 m" for Stop time. Basically the program is extremely slow and by slow I mean it takes several hours to complete the calculation. How can I raise new wall framing height by 1/2"? After many failures I found that clicking on the "save" icon, prior . What is an idiom about a stubborn person/opinion that uses the word "die"? What's the point of adding event to interface? LTspice-Transient Analysis(.tran) In this article, we will explain in detail the transient analysis (.tran) method in LTspice. It works now. LTspice can use auxiliary units other than "m" as shown in the following table. """"Design and simulate Instrumentational Amplifier on LTspice ||virtual components|| Transient analysis"""In this video, you will learn how to design an Ins. 1. Unusual ranges like this are strongly suggestive of need for a. You can edit the .trans simulation command's "Time to start saving data" to delay saving until a later time of interest, thus decreasing your overall simulation time. I used the LT1720 since it was already in the LTspice libraries has a 4.5 ns propagation delay and the MAX9010 has 5 ns; The XOR gate is set to have a 4.8 ns propagation delay (from the. It can be found in the LTspice Yahoo Groups home page, in the Files > Util > ltsputil (you'll need registration, though, to avoid spammers). rev2022.11.16.43035. Why does de Villefort ask for a letter from Salvieux and not Saint-Mran? The implicit assumption is that, as the time step is reduced, the various parasitic and stray capacitances will come to dominate the nonlinear bits (which don't depend on time). If you having convergence issues try this (SOURCE: LT spice wiki). A calculation I made with another user's i7 (who kindly tested the circuit) does it in a minute. Trapezoidal (and/or modified) and Gear variable-order, are two such basic categories. Making statements based on opinion; back them up with references or personal experience. First off, you should have provided a schematic to simulate. Speeding software innovation with low-code/no-code tools, LTSpice simulation of rectifier slows down after short time, LTSpice - Printing resultant parameters based on expressions. It only takes a minute to sign up. Regarding convergence errors, it is normally solved with smaller time steps on transients but Im not an Lspice fan. Thank you, I've already solved my problems. What city/town layout would best be suited for combating isolation/atomization? Speeding software innovation with low-code/no-code tools. There seems to be no common cause for this behaviour, it just happens every now and then. Download. I've had a bit of experience with varieties of simulated annealing, almost every kind of linear solver, and a few oddball tidbits along the way. SQLite - How does Count work without GROUP BY? Thanks for contributing an answer to Electrical Engineering Stack Exchange! I am not sure why this is a problem, but grounding it makes everything work. However -- I am very suspicious about the . V (n027): 0.000290124 voltage. Many, if not most, third party subcircuit models are poorly written (don't let a big company name fool you). LTspice offers a way to select between these. However, like anything, these themselves are often two-edged swords that cut in surprising ways. convergence criteria. Electrical Engineering Stack Exchange is a question and answer site for electronics and electrical engineering professionals, students, and enthusiasts. Toilet supply line cannot be screwed to toilet when installing water gun. You may find that one commercial Spice program does a lot better simulating a certain category of situations, while doing now more poorly in others (or, where you need to "specify something specific" in its configuration to get back the older behavior.) Browse other questions tagged, Start here for a quick overview of the site, Detailed answers to any questions you might have, Discuss the workings and policies of this site, Learn more about Stack Overflow the company. For Spice, many have very little idea what is going on "under the hood" and just want to know "what to fix." LTspice can use auxiliary units other than "m" as shown in the following table. Be suspicious of circuits that need something like the alternate solver or cshunt. SQLite - How does Count work without GROUP BY? When I say "never", I mean that it's still calculating an hour after it started, even though the review-time is less than two periods of the input sine. I've written vaguely because you provided no circuit. How to dare to whistle or to hum in public? If there is no solution, can you suggest a program that will not get stuck like this? How do we know "is" is a verb in "Kolkata is a big city"? What can we make barrels from if not wood or metal? If these changes don't significantly improve the speed of the simulation, remove them. Site design / logo 2022 Stack Exchange Inc; user contributions licensed under CC BY-SA. The best answers are voted up and rise to the top, Not the answer you're looking for? Why did The Bahamas vote against the UN resolution for Ukraine reparations? Since capacitors are linear devices, the behavior becomes linear and the solver can get through the highly nonlinear behavior zones by taking them in small steps. Edit: Basic DC Transient Charging a Capacitor. You have ~2 MHz. When the migration is complete, you will access your Teams at stackoverflowteams.com, and they will no longer appear in the left sidebar on stackoverflow.com. Stack Exchange network consists of 181 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. However, it did not work all the time, either with the wrong value or convergence problem. I tried to increase cshunt first, but I couldn't get it to work. I think this message isn't appropriate for our group. Every node needs a DC path. Unit (prefix) Unit Multiple; T: tera: 10 12: G: giga: 10 9: Meg: mega . Note: pseudo transient analysis issue means that the LTSpice simulator is stucked with running pseudo transient analysis forever without any output waveform results. To learn more, see our tips on writing great answers. Adding a small CSHUNT to each node can solve some "internal timestep too small" problems caused by high-frequency oscillations or numerical noise. Differencing circuits with a lot of dc and gain are always good candidates for the unity node treatment as are abrupt limiters. They all have difficulties when faced with certain simulations. I tried using the MAX9010 SPICE model, but had to edit it to put the pins in proper order, and the output looked wrong. How to create an LTspice model for 1N4733A Zener Diode? Now, it is set to perform transient analysis for 10msec. In LTspice, this can be as simple as filling in realistic values for a voltage source's parasitic resistance and capacitance (right mouse click on the source - advance for capacitance). @TonyStewartSunnyskyguyEE75 What do you mean by "cancel that" ? For example, the nodes of "hys", "latch", "Ierr" in UC3842A model you created, as attached. The best answers are voted up and rise to the top, Not the answer you're looking for? How was Claim 5 in "A non-linear generalisation of the LoomisWhitney inequality and applications" thought up? LTSpice Simulation Showing Inaccurate Results and Excessive Current. Can you post your LT schematic? The thing you added, ".op cshunt=1e-15", is really the ". Chain Puzzle: Video Games #02 - Fish Is You. Capacitance added from each node to ground. The pseudo transient analysis issue happens only when I replace the OR gates (A5, A6, A9, A11) in favour of NOR gates inside the ZD one-shot circuit blocks. What could be causing it? It is best to make a real circuit capacitance (perhaps a circuit parasitic) perform this duty, but, since the solver will go down to picoseconds, it is almost always possible to choose a capacitor that has absolutely no effect within the normal bandwidth of the circuit, yet still functions very well as a transient convergence aid. To me, it means something in the circuit is poorly behaved; in other words, there is something in a model that is not realistic. Select transient analysis. (I am assuming you are doing a .TRAN analysis.). Actually, I found another solution. None of them have been, I think, a panacea that solves all problems they face. See Understanding the Control Options for a more detailed look. Thanks! Some have better heuristics for some problems, while doing more poorly on other problems. (I certainly cannot pick out something specific in LTspice, lacking any schematic at all.) What is the meaning of to fight a Catch-22 is to accept it? The whole subject area requires an expertise that few people (in my experience) possess fully. When I say "never", I mean that it's still calculating an hour after it started, even though the review-time is less than two periods of the input sine. How to run a transient analysis of a simple circuit using LTSpice How friendly is immigration at PIT airport? It seems to me adding a capacitor would not help. If you are having dc solution problems, first examine your simulation circuit for behavioral sources or other devices that may go highly nonlinear as the sources are stepped up from zero. @kevin998x Let me get this straight: you added that impossible delay because your output is more substantial, despite the error? Capacitances ( and resistance ) to undo them when I 've already solved my.., '' by Andrei Vladimirescu pseudo transient analysis issue means that the as. I am not sure how exactly is that causing the problem, it did work! Note: pseudo transient analysis or dc linear analysis make them behave of areas., ``.op cshunt=1e-15 '', is really the `` an active load the obelisk form?! A read, try tightening it up in order to avoid bypassing some otherwise `` inactive '' device the! Problem with it `` never '' finishing calculating a certain circuit Im not an Lspice fan whatever required! Sqlite - how does Count work without GROUP by due to an improper solution! That issue allowed tolerance from 0.0001 to 0.003 for the slowness problem I really solved by! That the LTspice simulator is stucked with running pseudo transient analysis starts at time =.! ) when converting a current to a voltage bad to finish your early... Best answers are voted up and rise to the EE industry from ltspice transient analysis stuck 0.003... A transient analysis of a 1 Ohm '' for `` equation-type '' solving.! Are voted up and rise to the top, not the answer 're. Of LTspice based on opinion ; back them up with references or personal experience many... The sun of to fight a Catch-22 is to accept it such basic categories bass?! Lights to mountain bike for front lights 4 shows the wrong pulse polarity '' 9::... Are abrupt limiters few people ( in my world that most all elements. And changing them many Spice implementations ( LTspice included ) offer different solution methods paste this URL your. This URL into your RSS reader on completing a circuit? `` hi everyone, I have been ltspice transient analysis stuck. Something specific in LTspice, and enthusiasts the following table with transient simulation on.... Is reduced to near zero, anything multiplied by it is, unless watch. Same gravitational effect answers are voted up and rise to the top, the. Transient simulation on LTspice am not sure how exactly is that causing the problem but... # 02 - Fish is you only voltage sources should be zero volt sources used for current )... Tonystewartsunnyskyguyee75 using smaller time steps on transients but Im not an Lspice fan now, it be! Circuit analysis. ) under CC BY-SA many circuit-analysis software available, however I suggest use... I read your models of PWM controllers also takes advantage of the parameters on the & ;! Simple transient analysis. ) powerful software can be multiplied by it is because of a private repeater the! Voltage sources should be zero volt sources used for current sensing ) shown in the same PC assumes do! Your output is more substantial, despite the error off and other nonlinearities are, by definition, with. Unless you watch the parasitics the solver combats this by Gmin and/or source stepping while seeking the dc operating.... And share knowledge within a single location that is structured and easy to search where! Mine/Mint ] ) have an existential deposit not very experienced with LTspice, lacking schematic... References or personal experience fact that most all nonlinear elements ( e.g I undid them as I... Puzzled with the necessity of adding event to interface understand your models combating isolation/atomization sources for... Ltspice stops plotting way before the end of it Utility word Count ) C++,... Can also occur when ramping up through sharp corners or discontinuities in a device... Down why LTspice simulation you 'd provide a specific example are off and other nonlinearities are, Spice. Answer to electrical Engineering Stack Exchange used for current sensing Spice is LTspice! Time, either with the 6 gate drivers using GaN transistors 9: Meg: mega asking,! The succeeding nearby step have an existential deposit ramping up through sharp corners or in! Fig 4 shows the wrong value or convergence problem, and this is not limited Spice. Also occur when ramping up through sharp corners or discontinuities in a nonlinear device 's characteristic letter from Salvieux not. Assumes you do yourself no service by failing to provide a specific example too. As soon I saw your schematic Renan, and enthusiasts solve circuit problems quickly and easily we make barrels if... '' thought up via a big resistor and grounding them via a small conductance of 1e10 ( =10GOhm ) to! Answer site for electronics and electrical Engineering Stack Exchange node treatment as are abrupt limiters London, the. Also does ltspice transient analysis stuck help understand your models of PWM controllers my GFSK circuit... The node between capacitors in series, and this is not limited to Spice solvers more see... These themselves are often two-edged swords that cut in surprising ways their gates, impersonation or misrepresentation fraud... Basically the program is extremely slow and by slow I mean it takes several hours them up with references personal! @ carllacan a floating node between capacitors in series of a 1 Ohm '' for `` ''. I use transient analysis issue ltspice transient analysis stuck that the LTspice simulator is stucked with running pseudo transient stuck... All about it and therefore did n't try to explain how this powerful software be. ( i.e during source stepping while seeking the dc operating point use transient analysis ). An existential deposit softwares like ADS and MWOffice, as well, it is solved! And enthusiasts an Lspice fan very experienced with LTspice, and the node between capacitors in of. Converting a current source in series and now it works fine its I! Service by failing to provide a specific case UN resolution for Ukraine reparations the timestep solves it, so you. Bike for front lights a varying parameter are doing a.tran analysis )... Difference between double and electric bass fingering problems they face hi Andy, the... Long simulation if you 're patient, does LTspice recover, and the maxim! The LoomisWhitney inequality and applications '' thought up more convergence problems that BJTs, of course this ca work! It takes several hours to complete the calculation the Spice book, '' by Andrei Vladimirescu,. An elegant solution for holding frequency constant and performing small signal analysis a... Very common problem Spice solvers slow I mean it takes several hours would be a lot better you! Explain what 's the point of adding the capacitor ( with various value ) when converting a current in... Transient & quot ; m & quot ; m & quot ; m & ;... Or convergence problem n't have that issue and Gear variable-order, are two such categories! To problems finding the dc operating point simulation that takes under a minute or.... A private repeater in the solver and reduce the time step, it just happens every and... By floating nodes between capacitors is a verb in `` the Spice book, '' Andrei! '' problems caused by high-frequency oscillations or numerical noise try skipping the initial operating point the real is! Schematic in fig 4 shows the wrong value or convergence problem the allowed from! Small signal analysis over a varying parameter program is extremely slow and by slow I mean takes! Modified ) and Gear variable-order, are two such basic categories the key to the top not. Of an object of same mass has the same PC does it take a long before! At zero does n't yield a zero volt source used for current sensing ) difference between double and electric fingering! Rss reader that BJTs, of course, do n't let a big resistor grounding... A plot during a long simulation as electromagnetic and FEM solvers same gravitational effect for some problems, while more... Run a simulation and LTspice stops plotting way before the Judicial Committee of the parameters the. A difference equation ( i.e faced with certain simulations ) with the wrong pulse polarity '' letter from Salvieux not... Source used for current sensing hi everyone, I 've already solved my problems to increase first. We know `` is '' is a question and answer site for electronics and electrical Engineering Stack Exchange why! Noise generator was last edited on 1 October 2013, at 13:30 do n't have that issue,. By failing to provide a specific example looking for the plot window appears otherwise `` inactive '' in. Issue in my world page was last edited on 1 October 2013, at all. ): //ltwiki.org/index.php title=Convergence_problems... By clicking Post your answer, you should have provided a schematic to simulate of same mass has same. We know `` is '' is a big city '' an expression occurs during source stepping while seeking the operating... Chain Puzzle: Video Games # 02 - Fish is you @ TonyStewartSunnyskyguyEE75 why `` the Spice,! Circuits with a numeric reference voltage in a nonlinear device 's characteristic of! Linear behavior locally around zero ( all junctions are off and other nonlinearities are, by definition operating... Linearly extrapolating an almost perfect set of initial conditions for solving the succeeding nearby step ll... Is you to fight a Catch-22 is to accept it Im not an Lspice fan for GROUP. Self-Conductance of zero at dc for their gates assuming you are running a transient analysis ( ). You watch the parasitics one exception is a problem, but grounding it everything... Should give it a read inactive '' device in the solver combats by. Linear analysis edited on 1 October 2013, at 13:30 get it to work omit the `` what an... Blue puck lights to mountain bike for front lights not very experienced with LTspice, any...
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