What is LTspice?

LTspice is a SPICE simulator provided free of charge by Analog Devices.
LTspice excels in calculation speed and convergence, has no node limit, and includes circuit/symbol editors and a waveform viewer.
It also incorporates a vast number of macro models for Analog Devices products and allows for DC, AC, transient analysis, etc.
An update occurred in November 2023, releasing LTspice 24.

• 1999: LTspice
• 2008: LTspice IV
• 2016: LTspice X VII
• 2023: LTspice24

• Download LTspice here

Main Changes (LTspice 17 → LTspice 24)

LTspice is a SPICE simulator provided free of charge by Analog Devices.
LTspice excels in calculation speed and convergence, has no node limit, and includes circuit/symbol editors and a waveform viewer.
It also incorporates a vast number of macro models for Analog Devices products and allows for DC, AC, transient analysis, etc.
LTspice 24 was launched with a version update in November 2023.

・Performance Improvements
Improved simulation speed
Changed the default RTOL value

・Waveform Viewer Improvements
Zooming and panning of waveforms are now possible while the simulation is running
Easier vertical movement of plot panes
Added a right-click menu

・Addition of FRA (Frequency Response Analyzer) Functionality
Added 4-terminal FRA probe
Phase margin (Phase + 180) plotting

How to Change Toolbar Icons and Keyboard Shortcuts

How to Change Toolbar Icons

If you want to use the old version's toolbar icons, you can revert to them using the steps below.

Steps

Click "Settings" → "Schematic" → "Keyboard Shortcuts" on the toolbar.

• This option was called "Control Panel" before LTspice 17.1 but was changed to "Settings" starting with LTspice 24.

How to Change Keyboard Shortcuts

Steps

Click "Settings" → "Schematic" → "Keyboard Shortcuts" on the toolbar.
Or select "Help" → "Keyboard Shortcuts" from the toolbar.

Click "Restore LTspice Classic Values" to change to the shortcuts of the previous version.
You can also select individual items and assign custom shortcuts.

FRA（Frequency Response Analyzer）

FRA (Frequency Response Analyzer)

Feedback circuits like DCDC converters require stability evaluation, including loop gain and phase margin.
For operational amplifiers, simulation is performed using AC analysis. However, AC analysis cannot be used for DCDC converters because they are discontinuous circuits with switching behavior.

Until LTspice 17, loop gain was calculated by repeating .measure command descriptions and transient analysis.
In LTspice 17.1, the FRA command (Transient Frequency Response) was added, making loop gain verification easier.
LTspice 24 added a 4-terminal FRA probe, simplifying the analysis of arbitrary points, inverting outputs, current feedback, and enabling FRA analysis of μModule products with internal top-side feedback resistors.

LTspice17

FRA command (Transient Frequency Response) added in LTspice 17.1

4-terminal FRA probe added in LTspice 24

LTpowerCAD

LTpowerCAD is a power supply design tool from Analog Devices.
LTpowerCAD makes it possible to design circuit parameters for DC-DC converters and verify loop gain characteristics and phase margin, similar to the FRA mentioned above.
Circuits designed in LTpowerCAD can also be exported to LTspice.

• Download LTpowerCAD

Setting of Circuit Constants

Enter parameters into the light blue cells.
Can be exported to LTspice from the icon in the red box.

Loop Gain, Phase Margin (Bode diagram)