LTspice - Temperature and parametric sweep at the same time (NTC problem) - Page 1
Forum section: electronics / beginners

author: Warhawk
author_rank: Frequent Contributor
timestamp: February 13, 2018, 03:24:29 pm
content: Guys,I use LTspice quite a lot but today I ran in a trouble which I am not able to solve.I have a simple resistor divider with an NTC. I'd like to see how my output changes with temperature (I am able to do this) and also how the bias resistor affects the curve.I am able to run these two simulations independently, but I don't know how to make a plot, which puts the data together (Y-V(out), X(temp)). I tried to fiddle with .meas but with no luck.Any tips for the magical trick?Thanks in advance!PS: Yes, I used google and spent significant time on this ;-) -> Wasn't lucky yet.

author: mikerj
author_rank: Super Contributor
timestamp: February 14, 2018, 10:09:34 am
content: It doesn't make much sense to do something like this in Spice. If you have the thermistor characteristic then it would be trivial to do what you want in Excel/Mathcad or equivalent.EDIT: Check theoriginal spice modelsfrom Vishay, they come with an example circuit that does what you want.

author: Ian.M
author_rank: Super Contributor
timestamp: February 14, 2018, 11:12:45 am
content: Your X axis is plotting Rbias. Click it (where the cursor changes to a ruler) and entertemperatureas the quantity to be plotted.When asking about LTspice sims, please post your .asc file, and link to any extra component libraries required. When asking about ploting problems, save the plot settings and zip up the .plt file with the .asc file. You can also include libraries and symbols in the zip, but please don't include the generated .raw, .net or .log files, as .raw files especially can get very big.I've recreated your sim using the Vishay LTspice models mikerj linked.

author: orbanp
author_rank: Regular Contributor
timestamp: February 15, 2018, 03:15:10 pm
content: For Ian's simulation to run in LTspice IV copy "NTCS0603E3103_MT.asy" and "VISHAY_LTSPICE_Therm_MC.lib" files from the Vishay zip file into the folder where you put your simulation files from Ians's zip file.Also add the line ".lib VISHAY_LTSPICE_Therm_MC.lib" to the schematics.Peter

author: Ian.M
author_rank: Super Contributor
timestamp: February 15, 2018, 04:53:57 pm
content: Quote from: orbanp on February 15, 2018, 03:15:10 pmThe explicit .lib statement isn't needed as the sim's thermistor U1 symbol NTCS0603E3103_MT.asy contains the attribute lineModelFile VISHAY_LTSPICE_Therm_MC.libThe easiest way to get it running quickly is to unzip my files and all the Vishay model files to the same folder, though if you want to be picky, only the .lib and .asy mentioned above are actually required from the Vishay zip.

author: orbanp
author_rank: Regular Contributor
timestamp: February 17, 2018, 12:49:49 pm
content: Quote from: Ian.M onYesterdayat 03:53:57 AMHi Ian,Thanks for pointing this out!I never realized LTspice had this feature.I guess you learn all the time...Peter

author: Warhawk
author_rank: Frequent Contributor
timestamp: February 17, 2018, 03:06:58 pm
content: Quote from: Ian.M on February 14, 2018, 11:12:45 amIan.M - thanks for going to the effort and reproducing my design. I really appropriate it. Also, note taken when it comes to *asc files. This makes perfect sense. I am going to open your file right now. I was trying to change quantity to temperature/temp before I asked but I must have done something wrong. It did not work for me.

author: Warhawk
author_rank: Frequent Contributor
timestamp: February 17, 2018, 03:08:32 pm
content: mikejr - I get your point but this is just a part of more complex simulation.