LTSpice: Questions from Newbie

[mrfunkyjay]

Hallo! First of all, let me introduce myself, my name is Kelvin. I came from Indonesia and now I am in Germany. I'm here to do my practical training in a light and electronic design company in Munich. For more than two weeks I spent my time here to learn PSPICE and LTSPICE from the basics. I have also read several tuts in pdf, e-books, or help topics but it seems like I will struggle more in learning this. Without forum, active discussion forum, I might get lost in my training period. Well, it is 6 months time and I have spent my first month learning this.

To be very precise, I am having several difficulties in learning this because my supervisor is very busy and I am here doing what I have done my own. So, from this forum I hope I can finish the tasks given by my colleague by asking and receiving answers from you guys.

Questions:

1. Is there any good books about LTSpice or SPICE modelling? I am really curious how people could know the SPICE model parameter, what does it mean, how do you convert the information from data sheet to SPICE model, etc. At first I wasn't that curious but since I am deep in this topic, I get excited myself.

2. Is there any good tutorials beside the getting started, etc. tuts from LINEAR TECHNOLOGY?

3. I have done a project with PSPICE and it comes into an error when I want to do transient analysis with temperature parameter in it. So several guys told me to change and upgrade to LTSpice, that is what I am exactly doing, am I in a right path?

4. Last but not least, why this is very difficult T_T

 

[Rami00972]

Hallo! First of all, let me introduce myself, my name is Kelvin. I came from Indonesia and now I am in Germany. I'm here to do my practical training in a light and electronic design company in Munich. For more than two weeks I spent my time here to learn PSPICE and LTSPICE from the basics. I have also read several tuts in pdf, e-books, or help topics but it seems like I will struggle more in learning this. Without forum, active discussion forum, I might get lost in my training period. Well, it is 6 months time and I have spent my first month learning this.

To be very precise, I am having several difficulties in learning this because my supervisor is very busy and I am here doing what I have done my own. So, from this forum I hope I can finish the tasks given by my colleague by asking and receiving answers from you guys.

Questions:



1. Is there any good books about LTSpice or SPICE modelling? I am really curious how people could know the SPICE model parameter, what does it mean, how do you convert the information from data sheet to SPICE model, etc. At first I wasn't that curious but since I am deep in this topic, I get excited myself.

2. Is there any good tutorials beside the getting started, etc. tuts from LINEAR TECHNOLOGY?

3. I have done a project with PSPICE and it comes into an error when I want to do transient analysis with temperature parameter in it. So several guys told me to change and upgrade to LTSpice, that is what I am exactly doing, am I in a right path?

4. Last but not least, why this is very difficult T_T

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[crutschow]

Hallo!
Questions:

1. Is there any good books about LTSpice or SPICE modelling? I am really curious how people could know the SPICE model parameter, what does it mean, how do you convert the information from data sheet to SPICE model, etc. At first I wasn't that curious but since I am deep in this topic, I get excited myself.

2. Is there any good tutorials beside the getting started, etc. tuts from LINEAR TECHNOLOGY?

3. I have done a project with PSPICE and it comes into an error when I want to do transient analysis with temperature parameter in it. So several guys told me to change and upgrade to LTSpice, that is what I am exactly doing, am I in a right path?

4. Last but not least, why this is very difficult T_T

1. A Google search for "Spice Modeling Books" turned up several but I haven't read any of them so have no particular recommendations for that. In general, unfortunately there's no direct conversion from data sheet parameters to SPICE models.

2. There are numerous books on PSpice since it's widely used. Have no particular recommendations though.

3. SPICE is rather notorious for having convergence problems. Sometimes changing some of the analysis options such as reducing the tolerance on the current, relative error, charge, or voltage will help. Also changing the Transient Analysis Method from Trapezoidal to Gear sometimes helps. If all else fails I will only simulate part of the circuit and then slowly add parts until I find where the problem is occurring.

LTSpice is designed for use with Linear Technology parts and is not a general purpose SPICE program. I don't believe that it's an upgrade from PSpice.

4. SPICE is difficult to use at times. Sometimes a simple appearing circuit will give convergence problems for no apparent reason. It's a great tool for designing and understanding circuits before you build them, but also can be frustrating.

And always see if the simulation results make sense. Most of the time SPICE gives a fairly accurate simulation of the actual circuit operation but occasionally it can give strange results. Make sure that the results seem reasonable for the circuit being simulated.

 

[Torben]

Hello Kelvin! Welcome to the forum.

Probably the single best place for information, models, and examples on LTSpice is the LTSpice Yahoo! group: **broken link removed** Join that group.

I found that I learned a lot about how to use LTSpice by looking through the models in the Files section of that group and using the examples.

Also, this forum is a good place to ask questions if you get stuck; lots of us use LTSpice ourselves.


Good luck!

Torben

 

[mrfunkyjay]

thanks all, yes I have learned those convergence you mentioned and yesterday I went home from my office with smile because I made it working. cool.

another task today was given by my colleague and I really need to ask you guys. This is kinda weird, I never experienced this kind of error before.

This is copied from the error log:

Direct Newton iteration for .op point succeeded.
Singular matrix: Check node q:u1:1#collector
Iteration No. 5
Fatal Error: Singular matrix: check node q:u1:1#collector
Iteration No. 5

It seems that I wanna blow my head, frustrating yes!

I am dealing with two major components here, the other one which is BAT54C settled because it used in previous schematics.

I have these:

1. BCR583
2. BSS138W

At first, I am really confused, there are errors like unknown subcircuit, u might ask, do I type the correct letter and number according the .subckt. Yes I did it.

You might again ask, whether the symbol with X prefix showed correct Value, the same like in .subckt. Yes I did.

Then it comes out again with another error, like missing model value, and spice gave me specific location at u1 that is this:

V1 N001 0 PULSE(0 5 0 1u 1u 996m 1000m)
R1 N005 N004 1k
R2 N007 N005 100k
R3 N008 N007 100k
R4 N009 N008 100k
R5 0 N009 100k
C1 Vcc N005 2.2µ V=16
V2 Vcc 0 5
XU1 N001 Vcc N004 BCR583
R6 Vcc N003 100k
C2 0 N002 1n
C3 0 N006 1n
R7 Vcc N002 10k
R8 Vcc N006 10k
XD1 N002 N006 N003 BAT54C
XU2 N003 N005 0 BSS138W
.include BAT54C.sub
.tran 2
.include BSS138W.sub
.include BCR583.sub
.backanno
.end

as u can see, the u1 is BCR583. from this, I am stucked. because of that singular matrix bla bla bla. arghh, I can't think of any answers, Ok now let me put the model and subcircuit statements.

********************************************
* BCR583 SUBCIRCUIT *
********************************************
.subckt BCR583 3 1 2
LBO 1 11 0.56n
LBI 11 12 0.77n
R1 12 111 10.0k RPLMOD1
LEO 2 22 0.56n
LEI 22 222 0.77n
R2 111 222 10.0k RPLMOD1
LCO 3 33 0.49n
CEB 11 22 0.07p
CCB 11 33 0.12p
CCE 33 22 0.12p
Q1 33 111 222 T0220
.ends BCR583

*****************************************
* T0220 SPICE MODEL (SIMILAR TO BC807) *
*****************************************
.MODEL T0220 PNP (IS=0.230P NF=1.000
+ BF=504.327 VAF=26.000 IKF=0.780
+ ISE=39.284F NE=1.944 NR=1.002
+ BR=23.000 VAR=4.500 IKR=0.195
+ ISC=0.118F NC=3.025 RB=0.800
+ IRB=0.100M RBM=0.400 RE=0.203
+ RC=0.262 CJE=57.177P VJE=1.000
+ MJE=0.470 FC=0.750 CJC=28.600P
+ VJC=1.000 MJC=0.520 XCJC=0.650
+ TF=0.664N TR=2.600N PTF=1.000
+ XTF=6.350 VTF=2.000 ITF=0.250
+ XTB=1.700 EG=1.110 XTI=4.800
+ KF=5.000F AF=1.000)

***** RPLMOD1 SPICE MODEL*****
.MODEL RPLMOD1 R (TC1=-2.1E-3 TC2=6.0E-6)

With this, I got two errors again, the RPLMOD1 seems undefined. How to make the errors vanished?

I will appreciate helps from u guys, the LTSpice group in yahoo seems dead for today, no one replies. So I tried to put my problem up here.

Thanks for your attention.

Best regards,

Kelvin Susanto