LTspice — The Complete Guide: Free Simulation of Analog Circuits and Power Supplies
LTspice is a free SPICE simulator from Analog Devices, and probably the most widely used simulator among electronics engineers. It is especially fast on switching circuits, has no limit on component count and may be used for professional work. It is free but not open source.
LTspice
Analog Devices
Fast SPICE simulator with no component limit, unusually strong on switching converters and power circuits.
Get it from the vendorWhat it is used for
- Power supplies — buck, boost and flyback converters, with models of real controllers from the Analog Devices library.
- Amplifiers and filters — frequency response (AC), noise and stability.
- Transient analysis — inrush currents, switching events and component stress checks.
- Sensitivity analysis — Monte Carlo and component tolerances.
Getting started
Draw a schematic, pick components from the library, set the analysis type (.tran, .ac, .dc) and run. Click on a node and the plot appears. You can import other manufacturers' models as SPICE files. Most Analog Devices examples come as ready-to-run LTspice files.
What to know
The interface is old-fashioned and takes some getting used to, and the built-in library is mostly Analog Devices parts. It runs on Windows and macOS; on Linux through Wine. If you want an open tool, choose ngspice with the Qucs-S interface, or the simulator inside KiCad.
Ngspice
Ngspice Project
Open-source SPICE simulator — DC, AC, transient and noise. The engine behind KiCad simulation.
Get it from the vendor
Qucs-S
Qucs-S Project
Circuit simulation with a graphical schematic front end over SPICE engines.
Get it from the vendor
KiCad
KiCad Development Team
Open-source PCB design suite, from schematic to fabrication files, with no limit on layers or board area.
Get it from the vendorSimulIDE
SimulIDE (open-source project)
Real-time circuit simulator with PIC, AVR and Arduino microcontrollers, an oscilloscope and a serial monitor.
Get it from the vendorThe bottom line
For power supplies and analog circuits, LTspice is an excellent, fast choice and free for commercial use too. For circuits with microcontrollers and code, SimulIDE is more convenient.