Questions tagged [ltspice]

Anything related to LTSpice. LTspice is a SPICE simulation, schematic capture and waveform viewer program from Linear Technology. LTspice is freeware with very liberal license, it is lightweight and isn't crippled in any way.

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2answers
927 views

Export error log values from LTspice

I have used .meas expressions to calculate harmonic values in LTSpice. The problem is that these are now in the error log and I cannot export them. Is there a way to export error log values in a .csv ...
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1answer
47 views

Back-to-Back PMOS high power dissipation

I have created a circuit in LTspice to switch between two power sources (10s Li-Ion batteries). V1 and V3 resemble the power sources which vary from 30-42V. V2 and V3 are output pins of an µC. R3 is ...
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1answer
802 views

LTSpice simulation stalls after 100ms transient with 'Heightened Def Con'

I simulate a system of two mutually delay-coupled electronic clocks (DPLLs - digital phase-locked loops). This worked well and also in reasonable time so far. However, moving into a particular regime ...
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3answers
3k views

Why does LTSpice sometimes stop printing midway through a simulation?

Sometimes I run a simulation and LTSpice stops plotting way before the end of it. There seems to be no common cause for this behaviour, it just happens every now and then. What could be causing it?
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32 views

Create a nested for loop to sweep two parameters (x,y) to calculate a function E(x,y)

So I would like to plot a 3D space of a function while sweeping two other parameters. I am sure this is not possible to plot in LTspice but is there any way to sweep two parameters while measuring a ...
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1answer
87 views

What is the cause for a 180 phase shift between current and voltage in LT-spice simulation

Just by clicking on the resistor, I got a display of the plot of current passing through it, marked with I(R3). In my opinion it must be in phase with the voltage across the resistor, but on the ...
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1answer
36 views

AC Simulation in Power supply simulators

I would like to design a boost converter using LM3481 from texas instruments. To de the job, I have selected TINA TI circuit simulator, where the average model of LM3481 is given. So I have used this ...
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1answer
298 views

Efficiency question of # of LEDs for 6 volt 4 cell Joule Thief Flashlight circuit

This is a high voltage Joule Thief circuit simulation I developed in LTSpice. I am sure that it qualifies as a true Joule Thief because, in the picture below, we are zoomed into the "dead" voltage ...
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0answers
59 views

Capacitor Storage Circuit Having Lower Voltage Than the Simulation

I designed a circuit to store a pulse of 8 volts and duration of 40 micro seconds. When I simulated the circuit it reached 3.5 volts and discharged.The circuit and the simulation is given below; In ...
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0answers
29 views

MCP1630 Spice model

Does anyone knows where I can find MCP1630 spice model ? I realy need it to complete my project and microchip does not provide the spice model of this device. On my behalf, I do not master SPICE to ...
3
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1answer
51 views

LtSpice antisymmetric sine pulse

I am trying to create a pulse voltage source in ltspice. The pulse should look like a half cycle of a sine wave however the rise and fall times should be different. I can create such pulse with the ...
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0answers
95 views

Can't run mosfets in one leg configuration with ACPL 337J optocoupler

I am working with a four pin MOSFET(C3M0030090K). You can find the datasheet here. The gate driver which I am using is ACPL 337J (datasheet here). The mosfets are in one leg configuration like this: ....
3
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2answers
121 views

Minimoog oscillator LTSpice simulation problem

I am running a simulation on the Moog Minimoog Model D oscillator in LTSpice. The circuit with the models needed is attached below. The square wave and triangular wave generation work as expected. ...
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2answers
65 views

LTSpice PWL issue with Trigger

Perhaps someone can help me. I have a problem with the trigger function in LTSpice. I load a PWL file and add the following Syntax behind it: PWL (File.xx) Trigger V(n001)>1 LTSpice gave me an ...
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1answer
63 views

What is the expression for collector current (Ic) in function of CTR for optocoupler?

I'm just asking about expression for collector current (Ic) of optocoupler in function of CTR because my simulation results doesn't fit with the CTR=Ic/If equation. Simulating the part CNY17-3 with ...
2
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1answer
439 views

Behavioral inductor (current dependent) in LTspice

I am trying to make current dependent inductor in LTspice according my mesurements. LTspice includes feature flux where "x" is referred to inductor's current but when I used it in combination with my ...
2
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1answer
1k views

LTSpice capacitance dependend on voltage source

I am looking for a way to change the value of a capacitance dependent on the voltage source of the circuit. How do I create a voltage dependent capacitor in LT spice? Edit: Two capacitances in a row ...
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0answers
26 views

How to estimate NMOS Cds+Cdb capacitance from VDMOS Pspice/LTSpice model?

I'm designing a fly-back converter and in order to calculate the switching frequency I want to know a method or formula of how estimate the Cds+Cdb capacitance of NMOS switch using the Pspice ...
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4answers
869 views

How to improve my curve fitting for an LED in spice

I have an LED that I'm working with, actually it's not a discrete part but on silicon. Anyway all I have is a curve for it and I was trying to work up a spice model in LT-spice. I followed this ...
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2answers
154 views

LTspice: Simulating a Van Der Pol Oscillator

I am trying to simulate the oscillator with an RLC circuit with the initial condition V(V1) = 0 and D(V(V1)) = 0. Since LTspice does not allow initial condition with time derivatives, I set the ...
2
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2answers
86 views

Non-linear Inductor LTSpice

I am trying to implement a non-linear inductor in LTSpice and to get it to saturate. I am using the following directive between N1 and N2 as advised in the help files: L1 N1 N2 Hc=12 Br=0.2 Bs=0.4 A=...
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1answer
72 views

LTSpice - envelope detector LPF behaving like buffer

I have an issue with an LTSpice simulation and I'm not sure if the issue lies in the simulation setup or somewhere more basic. The simulation is as follows: The system is as follows: on the left, ...
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2answers
4k views

Add a trace from a directive in LTSpice

I have a circuit in LTSpice in which I want to measure some differential voltages, currently I'm manually adding the traces using the "Add Trace" menu in the plot view and writing its expressions. I ...
3
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1answer
6k views

Use variable in SPICE parameter list

I'm using LTSpice XVII to try and simulate a circuit. I've created a schematic which uses a Pulse voltage source to simulate a rotary encoder as follows: As you can see in the PULSE component, I'm ...
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1answer
58 views

My calculation for an RC circuit are not agreeing with the LTSpice simulation

I am doing calculations for an RC circuit to create a first order low pass filter. The input is a 5V peak periodic square wave with a 10kHz frequency. The resistor is 220 Ohms and the Capacitor is ...
2
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1answer
1k views

Using a single phase induction motor equivalent circuit in LTspice

I was planning to simulate a circuit which will control a single phase induction motor in LTspice where mains is 230VAC 50Hz. In my previous question, I failed to find an example: Modelling a "...
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1answer
908 views

Modelling a “single-phase permanent split-capacitor motor” in LTspice

I'm planning to use an AC fan in an LTspice simulation. The AC fan is made up of a single-phase permanent split-capacitor (PSC) motor. Here is the actual fan: http://uk.rs-online.com/web/p/axial-fans/...
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0answers
58 views

Why does the frequency of an oscillator changes with the time duration of .TRAN command?

I have simulated an oscillator circuit using OTA in SPICE. It is a self starting oscillator. However, the frequency of oscillation does not change with the bias current but changes with the duration ...
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0answers
51 views

LTSpice .MEAS Command: Measuring Mag and Phase Data

I got a real stumper of a LTSpice question for y'all. I'm do an AC analysis to calculate input impedance by setting the input to AC 1V and then adding the trace "1 / I(v1)" (where V1 is the source). ...
2
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3answers
169 views

Does the LT Spice monte carlo simulation definitely output the max and min voltage for any number of simulation runs?

I have the following circuit, in which i need to calculate max and min voltages possible (considering resistor tolerance). Does running a monte carlo simulation consider the absolute max and min ...
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0answers
119 views

Problem driving MOSFET with ACPL 337J optocoupler

I want to drive a mosfet. I am using an ACPL 337J optocoupler to drive it. Here is the schematic:- But I am facing problem while driving the mosfet. The signal at gate of mosfet should be a PWM but ...
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2answers
219 views

Why is LTSpice Bode plot disagreeing with a linear plot?

Here is a picture of an amplifier that I'm simulating using LTSpice. When I insert a sine wave of 0.01 volts and 314Hz as an input, I get this: The output is taken from the collector and is ...
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4answers
141 views

Why does LT spice limits frequency domain output to 65535 data points?

Background: I ran a simulation and I am generating the S21 gain of a circuit I am working with dembedding and wanted a 100% accurate and wanted a ridiculous amount of data points and when checking my ...
2
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2answers
2k views

start a LTSpice simulation using code in MacOS

Help me please, I'm looking for the solution how to automate spice simulation with python on MacOS, currently, I'm thinking to use LTspice. However, I'm open to any proposal. I want to make ...
2
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2answers
575 views

Confusion with “skip initial operating point solution” in LTspice

I'm trying to simulate the following boost converter to see Vout versus Vin: In LTspice if I run the simulation for the first 250ms I obtain this plot where Vout < Vin: But if I chose "skip ...
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1answer
39 views

Values of components in ACPL 337J

I was going through datasheet of mosfet gate driver. I wonder why is the value of component the specified one only. On page no. 13 fig 23, why the value of resistor between pin 3 and pin 6 is 10k ohm ...
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0answers
53 views

Clapp Oscillator Oscillating Frequency Strongly Dependent on the Transistor

For temperature sensing purposes, I have been challenging myself to design a dual mode crystal oscillator operating at the frequencies 30MHz and 90MHz (fundamental tone and the third overtone, ...
3
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1answer
877 views

How to add a multi-emitter BJT to LTSpice?

I want to simulate the standard TTL NAND gate which contains a multi-emitter BJT transistor in LTSpice. I've searched the components available in LTSpice but didn't found this component. How can I add ...
2
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2answers
1k views

LT-Spice RL circuit simulation ill behaved current

I am trying to simulate a RL circuit in DC with LT-spice as follows: NOTE that the inductance is 0.0229 H although in the picture you see 229 Now, according to my calculation, what I would expect is ...
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1answer
109 views

LTSpice: simulate transient voltage and current in RL-circuit

My goal is to calculate transient current and voltage in a following circuit: Also, immediately after the switch is closed, initial current is 0 and then it exponentially increases until the value ...
2
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1answer
90 views

What's wrong with this circuit built on opamps?

I have built this circuit in the LTSpice, but it refuses to simulate the operation using normal solver, but shows great results using alternate. This source says Be suspicious of circuits that need ...
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1answer
43 views

LTspice: Including Time Derivative of a Node Voltage in Initial Condition

I am trying to simulate an RLC circuit with the initial condition that V1(0)=2 and V1'(0)=0. I used D(V(V1))=0 in my spice directive, but I don't think the condition on time derivative has actually ...
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1answer
403 views

Problem driving IPB065N15N3G MOSFET with HCPL-316J driver

I want to drive an IPB065N15N3G MOSFET. I am making a boost converter. The driver I am using is the HCPL-316J (a combined optocoupler and driver). Below is a picture of my schematic. Please tell me ...
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1answer
2k views

LTSpice component attribute editor problem

I have a problem in LTSpice with calling "component attribute" on both versions IV and XVII. Normally you should be able to call the component attribute window by pressing Ctrl+RightClick on the ...
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1answer
37 views

Fatal Error Audio equalization simulation LTSpice

I'm doing a 3s audio.wav simulation on LTSpice with the following circuit (3 band pass filters and amplifiers): In this example it's boosting the bass and attenuating the highs. It loads the first ...
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3answers
336 views

LC Circuit LTSpice Simulation With Time Switch

I'm sorry if this topic isn't adequate for the forum. Does anyone know how can I make this LC circuit simulation for \$v_{c}(t)\$? The original circuit is the one shown in the figure. \$v_{C}(t)=\...
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2answers
3k views

LTSpice Error: timestep too small

This is the error I see: This is my Simulation Command. What is the issue here?
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1answer
31 views

Gain with inversing Op Amp on Equalizer

I know I posted a question about this circuit before, but I'm running into a problem. I know this is a terrible equalizer design but I'm trying to learn to put in use what I learnt with Op Amps and ...
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1answer
69 views

Ltspice Full-wave rectified signal issue

I have done a simple simulation with Ltspice with a bridge diode rectifier as shown with the picture below. However I have observed an issue in the shape of the output voltage and not the current ...
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0answers
29 views

How can I simulate “definitions” (DEF/ENDDEF) and to draw (DRAW/ENDDRAW) on LTspice, is it possible?

I have the circuit XR2211 described on "definition" with the commands DEF and ENDDEF, and drawn with the command DRAW and ENDDRAW. Working simulations in LTspice there are many information, but this ...