LTspice XVII is a schematic-driven circuit simulation program. The LTspice simulator was originally based years ago on Berkeley SPICE 3F4/5. The simulator has gone through a complete re-write in order to improve the performance of the simulator, fix bugs, and extend the simulator so that it can run industry standard semiconductor and behavioral models. A digital simulation capability, including co-simulation, has been added. Extensive enhancements have been made to the analog SPICE simulator, such as parallel processing and dynamic assembly and object code generation in the SPARSE matrix solver to make LTspice XVII the industry superlative analog simulator.
Many Linear Technology products are modeled with proprietary building blocks and/or proprietary hardware description languages that accurately encapsulate realistic behavior with custom macromodels. This allows a SMPS to be prototyped rapidly via simulation.
LTspice is intended to be used as your general-purpose SPICE simulator. New circuits can be drafted with the built-in schematic capture. Simulation commands and parameters are placed as text on the schematic using established SPICE syntax. Waveforms of circuit nodes and device currents can be plotted by clicking the mouse on the nodes in the schematic during or after simulation.
An invaluable reference that complements this documentation is the 2nd Edition of Semiconductor Device Modeling with SPICE by Giuseppe Massobrio and Paolo Antognetti, McGraw Hill, 1993 and later reprints. That book documents the semiconductor device equations and extensions that have been used in various commercial SPICE programs including those used in this one. For BSIM 3 and 4 devices, see the relevant documentation available from the UC Berkeley CAD group.
LTspice is a registered trademark of Linear Technology Corporation.