1. Skip to navigation
  2. Skip to content
  3. Skip to sidebar

Solutions Search - LTspice

LTspice IV is a high performance SPICE simulator, schematic capture and waveform viewer with enhancements and models for easing the simulation of switching regulators.  Our enhancements to SPICE have made simulating switching regulators extremely fast compared to normal SPICE simulators, allowing the user to view waveforms for most switching regulators in just a few minutes. Included in this download are LTspice IV, Macro Models for 80% of Linear Technology's switching regulators, over 200 op amp models, as well as resistors, transistors and MOSFET models.

Download LTspice IV

Please send questions or comments to ltspice@linear.com

Using LTspice to Characterize Capacitor Banks

Steve Knudtsen - Field Applications Engineer Jul 12th 2016
Capacitor banks are used to filter noise and provide energy storage for fast load transient response.  For modeling the stability of a DC/DC converter the ESR of the capacitor bank is needed.  This can be easily done if only one type of capacitor is used with multiple capacitors in parallel.  This is difficult ...

Blog Post LTspiceIV 

 

LTspice: AC Analysis Using The Step Command

Gabino Alonso - Strategic Marketing Engineer Jul 4th 2016
In LTspice, AC analysis involves computing the AC complex node voltages as a function of frequency using an independent voltage or current source as the driving signal. The small signal analysis results are plotted in the waveform viewer as magnitude and phase over frequency. AC analysis in LTspice has a number of settings: ...

Blog Post LTspiceIV 

 

High Speed Peak Detector

Hassan Kelley - Field Applications Engineer Jul 4th 2016
Introduction Peak detectors capture the extrema of the voltage signal at its input. A positive peak detector captures the most positive point of the input signal and a negative peak detector captures the most negative point of the input signal. Ideally the output of the peak detector circuit tracks or follows the input voltage ...

Blog Post Circuit LTspiceIV 

 

Baseband Design Example for a Low-Power IQ Modulator

Bruce Hemp - Applications Section Leader Jul 1st 2016
Introduction This basic low power modulator was described in the LT Journal Nov 2015 article. In this blog post, we will show how to: Use simulation to validate the filter design, and Reduce DC offsets by utilizing Differential Amplifiers for the baseband drive. Also shown are some miscellaneous tips to help complete ...

Blog Post Circuit LTspiceIV 

 

AC Line Overcurrent Indicator

Philip Lane - Field Applications Engineer
Scott Olson - Associate Engineer
Jun 4th 2016
Circuit Description This circuit design is to monitor the average current in an AC line-connected load and to illuminate an LED if it exceeds a specified level. µPower, Low Voltage Comparator with Reference The basis of this design is the LT6703-2 which combines a micropower, low voltage comparator with a 400mV reference ...

Blog Post Circuit LTspiceIV 

 

LTspice: Using Time-Dependent Exponential Sources to Model Transients

Mitchell Lee - Applications Engineer
Gabino Alonso - Strategic Marketing Engineer
May 15th 2016
When working with Surge Stoppers or Hot Swap Controllers, occasionally there is a need to simulate a circuit's behavior with a specified voltage or current transient. These transients are usually modeled using a double exponential waveform characterized by a peak voltage, a rise time (usually 10%–90%), a fall time to 50% ...

Blog Post LTspiceIV 

 

LTspice: Behavioral Voltage Sources

Simon Bramble - Field Applications Engineer Apr 4th 2016
Nearly all circuits that you simulate need a voltage source of some kind. In LTspice, the humble voltage source rarely gets to demonstrate its true capabilities. This video will help you learn some of the undiscovered talents of the LTspice voltage source. In this video we’ll explore the power of the behavioural voltage ...

Blog Post Video LTspiceIV 

 

LTSpice: Plotting a Parameter Against Something Other Than Time (e.g. Resistance)

Joseph Spencer - Field Applications Engineer Mar 25th 2016
A common use for LTSpice® is to run a time domain transient analysis where a parameter (e.g. voltage or current) can be plotted against time. Occasionally, you may wish to know the behavior of a circuit versus another parameter such as resistance. This can be done by using the “.measure” and “.step” ...

Blog Post LTspiceIV 

 

LTspice: Generating Triangular & Sawtooth Waveforms

Gabino Alonso - Strategic Marketing Engineer Mar 16th 2016
Some of the most common waveforms needed in simulating voltage and current sources are sine, square, triangular and sawtooth shapes. LTspice® simulation software has a built-in pulse, sine, exponential, single frequency FM and an arbitrary piece-wise linear functions available in the source component editor. Although ...

Blog Post LTspiceIV 

 

LTspice: Importing and Exporting WAV & PWL Text Files

Simon Bramble - Field Applications Engineer Jan 20th 2016
Sometimes you may want to apply a voltage source to your circuit whose characteristics have been derived from an external source whether it is a WAV file or a just a list of time and voltage instances. LTspice allows you to do this and this video will highlight how to import and export WAV audio files as well as how to read ...

Blog Post Video LTspiceIV 

 

LTspice: Combining Multiple Model Instances Into One Symbol

Gabino Alonso - Strategic Marketing Engineer Dec 21st 2015
When you need multiple instances of a model, it is easy to copy and paste a symbol, but sometimes you can tighten up your schematics by using a single symbol to define multiple instances of same device. For instance, instead of placing four identical capacitor symbols in parallel, use one symbol times four, “x4”. ...

Blog Post LTspiceIV 

 

LTspice User Privacy Statment

Mike Engelhardt - Mgr. of Simulation Development Nov 12th 2015
As the Author and maintainer of LTspice IV, please let me assure you that LTspice does not nor has ever collected data about the user or any aspect of the user's design work. From conception of the project to release and over all the years of supporting the program, myself and my management have been committed to not ...

Blog Post LTspiceIV 

 

Achieving Low On-Resistance with Guaranteed SOA in High Current Hot Swap Applications

Dan Eddleman - Senior Applications Engineer Jul 29th 2015
Introduction The requirement for live insertion and removal in high current backplane applications demands MOSFETs that exhibit both low on-resistance during steady state operation and high Safe Operating Area (SOA) for transient conditions. Often, modern MOSFETs optimized for low on-resistance are unsuitable for high SOA Hot ...

Blog Post Circuit LTspiceIV 

 

LTspice: Speed Up Your Simulations

Gabino Alonso - Strategic Marketing Engineer Jul 20th 2015
LTspice is designed from the ground up to produce fast circuit simulations, but there is margin in some simulations to increase the speed. Note, there may be trade-offs in accuracy using the methods described here. For further details on any of these approaches, please refer to the LTspice Help File (F1). To measure the effects ...

Blog Post LTspiceIV 

 

SPICE Differentiation

Mike Engelhardt - Mgr. of Simulation Development Jun 19th 2015
Analog design engineers lean heavily on simulation to predict circuit performance. The value of a simulator hangs on how well it can predict physical reality, and how quickly it can produce results. Discrepancy between simulated and real performance can send a product into costly iterative debugging cycles. SPICE is used for ...

Blog Post LTspiceIV 

 

LTspiceIV: Voltage Controlled Switches

Gabino Alonso - Strategic Marketing Engineer Apr 9th 2015
LTspice includes a large number of excellent FET models, but sometimes you need to simulate a simple switch that opens and closes at specific times or under certain conditions.To insert and configure a switch in LTspice… (example is available at \LTspiceIV\examples\Educational\Vswitch.asc) Insert the symbol for the ...

Blog Post LTspiceIV 

 

LTC4226 Parallel MOSFETs in Hot Swap Circuits

Dan Eddleman - Senior Applications Engineer Mar 13th 2015
The Good, the Bad, and the Ugly Introduction While it is often desirable, and sometimes absolutely critical, to use multiple parallel MOSFETs in Hot Swap™ circuits, careful analysis of Safe Operating Area (SOA) is essential. Each additional parallel MOSFET added to a circuit improves the voltage drop, power loss, and ...

Blog Post Circuit LTspiceIV 

 

Loop Gain and its Effect on Analog Control Systems

Simon Bramble - Field Applications Engineer Jan 26th 2015
Abstract This article brings together the ideas of open loop gain, closed loop gain, gain and phase margin, minimum gain stability and shows how these parameters are interrelated in a feedback system. It examines loop gain in terms of a theoretical control system as well as practical electronic circuits, including linear regulators. Introduction Bob ...

Blog Post LTspiceIV 

 

LTspice: Connecting the Dots

Gabino Alonso - Strategic Marketing Engineer Jan 20th 2015
Sometimes the simplest things elude us. Typically, after placing components in an LTspice schematic you select draw wires (F3), left click to start a wire, left click again to change direction or join, repeat until your circuit is complete and then right click to cancel. But did you know you can draw wires through components ...

Blog Post LTspiceIV 

 

LTspice: Copy and Paste Between Schematics

Gabino Alonso - Strategic Marketing Engineer Dec 11th 2014
Sometimes the simplest things elude us. One feature not commonly understood in LTspice is how to copy and paste between schematics using the duplicate command. To copy objects from one schematic to another, in the source schematic, invoke the duplicate command (F6 or Ctrl + C) — the crosshair pointer changes to the duplicate ...

Blog Post LTspiceIV 

 

LTspice: SOAtherm Tutorial

Dan Eddleman - Senior Applications Engineer Oct 8th 2014
Verifying that a Hot Swap design does not exceed the capabilities of a MOSFET is a challenge at high power levels. Fortunately, thermal behavior and SOA may be modeled in circuit simulators such as LTspice IV® . The SOAtherm-NMOS symbol included in LTspice contains a collection of MOSFET thermal models developed by Linear ...

Blog Post Video LTspiceIV 

 

LTspice: Using an Intrinsic Symbol for a Third-Party Model

Gabino Alonso - Strategic Marketing Engineer Sep 9th 2014
LTspice IV can automatically create a symbol for a third-party model, or you can associate a third-party subcircuit with an LTspice intrinsic symbol, as long as the third-party .SUBCKT model and the intrinsic symbol share an identical pin/port netlist order. For example, to add an N-channel MOSFET transistor symbol to a schematic ...

Blog Post LTspiceIV 

 

LTspice: Modeling Safe Operating Area Behavior of N-channel MOSFETs

Dan Eddleman - Senior Applications Engineer Aug 22nd 2014
Introduction Often the most challenging aspect of Hot Swap™ circuit design is verifying that a MOSFET’s Safe Operating Area (SOA) is not exceeded. The SOAtherm tool distributed with LTspice IV® simplifies this task, allowing a circuit designer to immediately evaluate the SOA requirements of an application and ...

Blog Post LTspiceIV 

 

LTspice: Simple Steps for Simulating Transformers

Gabino Alonso - Strategic Marketing Engineer Jul 1st 2014
Here is the simple approach to simulate a transformer in LTspice IV: Draft an inductor for each transformer winding Couple them using a single mutual inductance (K) statement via a SPICE directive: K1 L1 L2 L3 1 The last entry in the K statement is the coupling coefficient, which can vary between 0 and 1, where 1 represents ...

Blog Post LTspiceIV 

 

LTspice: Basic Steps in Generating a Bode Plot of SMPS

Gabino Alonso - Strategic Marketing Engineer Jun 3rd 2014
Determining the open loop gain from a closed loop switch mode power supply (SMPS) is best solved using Middlebrook’s method, which appears in the International Journal of Electronics, Volume 38, Number 4, 1975. This method injects test signals into the closed loop system to independently solve for the voltage and current ...

Blog Post LTspiceIV 

 

LTspice: Simple Steps to Import Third-Party Models

Gabino Alonso - Strategic Marketing Engineer May 3rd 2014
It is possible in LTspice IV to create a new symbol from scratch for a third-party model but who has the time. Follow theses easy steps to generate a new symbol for a third-party model defined in a subcircuit (.SUBCKT statement). Open the netlist file that contains the subcircuit definitions in LTspice (File > Open or ...

Blog Post LTspiceIV 

 

LTspice: SAR ADC Driver Interface

Kris Lokere - Strategic Applications Manager - Signal Apr 3rd 2014
  High-performance SAR ADCs can offer amazing dynamic range and linearity at faster and faster sample rates. But how do you design the amplifier and interface at the analog inputs? LTspice IV can help. This video shows how to use LTspice to simulate the analog input interface of high-performance SAR ADCs. We will look ...

Blog Post Video LTspiceIV 

 

LTspice IV: Extracting Switch Mode Power Supply Loop Gain in Simulation and Why You Usually Don't Need To

Mike Engelhardt - Mgr. of Simulation Development Mar 3rd 2014
The gain of a negative feedback loop needs to fall with frequency below unity before too much phase shift occurs unless your aim actually is to make an oscillator[1]. This idea can be applied to the stability analysis of a Switch Mode Power Supply(SMPS). Even though a SMPS is an intrinsically non-linear circuit with no small- ...

Blog Post LTspiceIV 

 

LTspice IV: AC Analysis

Simon Bramble - Field Applications Engineer Feb 13th 2014
  Sometimes the frequency response of a circuit is more important than looking at the individual voltages or currents at a specific part of the schematic. LTspice IV can help you achieve this with its AC analysis function. This video shows you how to perform a basic AC analysis in LTspice as well as point out some capabilities ...

Blog Post Video LTspiceIV 

 

LTspice IV: Integrating Noise Over a Bandwidth

Gabino Alonso - Strategic Marketing Engineer Dec 19th 2013
LTspice IV can perform .noise analysis of a circuit, where the noise voltage density (V/√Hz) for 1Hz bandwidth) can easily be plotted for the output noise, input noise or for any noisy component like a resistor, diode or transistor. However, you can also easily integrate noise over a selected bandwidth in a .noise analysis. To ...

Blog Post LTspiceIV 

 

LTspice IV: Stability of Op Amp Circuits

Kris Lokere - Strategic Applications Manager - Signal Nov 6th 2013
  We all know that feedback circuits can oscillate. We may even know some tricks of how to fix it. But wouldn’t it be nice if our simulation tool could show us exactly what is happening, and why? This video illustrates how to use the .AC analysis to look at open loop gain and phase of operational amplifier ...

Blog Post Video LTspiceIV 

 

LTspice IV: Computing the Average or RMS Value of a Trace

Gabino Alonso - Strategic Marketing Engineer Nov 6th 2013
The LTspice IV waveform viewer can integrate a trace to produce the average or RMS value over a given region. To integrate a trace in the waveform viewer: Zoom in to the region of interest. Hold down the control key and click the label of the trace you want to integrate. Based on the physical units of the data trace, ...

Blog Post LTspiceIV 

 

LTspice IV: Using the .STEP Command to Perform Repeated Analysis

Gabino Alonso - Strategic Marketing Engineer Oct 7th 2013
There are two ways to examine a circuit in LTspice IV by changing the value for a particular parameter: you can either manually enter each value and then resimulate the circuit to view the response, or use the .step command to sweep across a range of values in a single simulation run.The .step command causes an analysis to be ...

Blog Post LTspiceIV 

 

What Is The LTpowerCAD Design Tool and How Is It Different From LTspice?

Henry Zhang - Applications Engineering Manager Sep 27th 2013
Today’s electronics systems require an increasing number of power rails and supply solutions, with the load range from a few mA for standby supply to over 100A for ASIC or FPGA core voltage regulators. It is important to have the appropriate solutions for the targeted applications and meet specified performance requirements, ...

Blog Post LTpowerCAD LTspiceIV 

 

LTspice IV: Annotating Schematic & Waverform Plots

Gabino Alonso - Strategic Marketing Engineer Sep 4th 2013
Adding informative comments to a schematic using text is very useful. However, there are times when adding a line, rectangle, circle or arc to a schematic can better illustrate a circuit. A classic example is highlighting a transformer core using two lines. In LTspice IV these graphical annotations are available under Draw in ...

Blog Post LTspiceIV 

 

LTspice IV: Parametric Plots

Gabino Alonso - Strategic Marketing Engineer Aug 6th 2013
Plotting results in LTspice IV is as easy as clicking on a node to show voltage, or a component to show current—the trace is then displayed in the waveform viewer. In transient analysis, the horizontal axis defaults to showing time, but you can always change the horizontal axis to show other quantities (such as current) ...

Blog Post LTspiceIV 

 

LTspice IV: Importing & Exporting PWL Data

Gabino Alonso - Strategic Marketing Engineer Jul 18th 2013
The LTspice IV waveform viewer is a handy way to perform basic measurements, but there are times when you need to export data from, or import data into LTspice to further evaluate a circuit. To export waveform data to an ACSII text file: Click to select the waveform viewer Choose Export from the File menu. Select the traces ...

Blog Post LTspiceIV 

 

LTspice IV: Piecewise Linear (PWL) Functions for Voltage & Current Sources

Gabino Alonso - Strategic Marketing Engineer Jun 10th 2013
Piecewise linear (PWL) functions are used to construct a waveform from a series of straight line segments connecting points defined by the user in LTspice IV. Since PWL functions are useful in creating custom waveforms, they are typically used in defining voltage or current sources. To add a PWL function to a voltage or current ...

Blog Post LTspiceIV 

 

LTspice IV: Noise Simulations

Tyler Hutchison - Signal Conditioning Design Engineer May 7th 2013
  LTspice IV can perform frequency domain noise analysis which takes into account shot, thermal and flicker (1/f) noise. The resulting noise density (in units of volts per square root hertz) can then be plotted to aid in circuit analysis and understanding. This video covers how to setup a .noise simulation in LTspice ...

Blog Post Video LTspiceIV 

 

LTspice IV: Undocumented Shortcuts

Gabino Alonso - Strategic Marketing Engineer May 1st 2013
There are several undocumented shortcuts in LTspice IV that you might find useful: Alt + left-click on a label, V(n008), in the waveform viewer to highlight that particular net in the schematic editor. To route wires at an angle, hold down Ctrl key as you draw them. Text with a preceding underscore character, e.g., “_FAULT”, ...

Blog Post LTspiceIV 

 

Too many results please adjust your filters