A set of tools I use to manage my ltspice and schematics. Barely usable for others now, but as soon as it is I will add some documentation.

ltmc.py - A montecarlo/minmax simulation generator

Take your existing simulation and transform it into a monte carlo like, or min/max tolerance simulation.

Monte Carlo

You should also specify the number of runs for this as it will use (pseudo)random numbers to have them deviate per run, so you can chose how often you want to run it.

Min/Max

By counting up a number and interpreting its bits as negative or positive tolerance indicators, this will test all combinations of far extreme tolerances. Be aware of that this will end up in 2**N runs for N components, and since ltspice itself only supports up to 100001, more than 16 components will not run. Given that usually a simulation runs longer than a second, this will most likely run days anyways so isn't feasible.

Specifying components and their tolerances

Single components

You can specify components like

ltmc.py -C R1 ltmc.asc

Without anything else, this will just select R1 and checks its tol SpiceLine value. If thats not present, its an error, unless you specify something else.

• -C R1:4 will set the component value (likely R since it seems to be a resistor) tolerance to 4%
• -C R1:R=4 alternative syntax explicitly chosing to set the resistance tolerance
• -C C1:Rser=4 selects for component C1 the Rser (serial resistance) component and a tolerance of 4%.
• -C C1:Rser=4,Rpar=10/20 selects C1 and sets Rser to 4% tolerance but RPar to 10/20 which means 10% lower and 20% higher tolerance

You can use multiple -C arguments or a list of them seperated by ; but be careful that the shell does not interpret it.

By component type

You can specify something for whole types

• -r Selects all resistors that have a tolerance value built into the schematic
• -r 4.5 Sets a tolerance of 4.5% for all resistors, regardless of the value in the schematic

Same goes for -c for capacitors, -i for inductors and -a for all three of them.

ltmanage.py Manage your 3rd party components

This is an upcoming tool. It will be possible to

• Update from URLs
• Store and mark components that are obsolete
• Unify the standard.* files from multiple sources
• Automatically check for each .asy if the .lib file is there
• For .lib files that do not seem to have a .asy try to automatically create or chose one
• Automatically assemble .lib files from multiple sources and assign a proper .asy file for it

ltgoogle.py Make it easier to get components from the web

Another upcoming tool. Will try to google component definitions. It can download and compare multiple hits and collect collateral information. Will be able to output configuration data for ltmanage.py to keep things updated.