Wow!
Thanks for the new version including TVS Diodes.
I think I saw a problem with one of the models. I have given some information to see if you duplicate my test. Maybe I am doing something wrong.
The SMCJ33A Model seems to have issues with low clamp currents.
Set up the following scenario:
Test Circuit
Circuit is Voltage Source
Series Current Limiting Resistor
Parallel TVS after the Series Current Limit Resistor
Ground
Make a pulse source
Starting voltage = 28V
Vmax = 80V
Delay =10ms
Rise & fall times = 1us
Time on = 50ms
Period = 100ms
Series Resistor Initial Value = 100m
TVS = SMCJ33A
Simulation set-up
Stop time = 200m
Time Step = 0.1us
Don¡¯t open the simulation with DC at 0V.
Run the simulation with the 100m Ohm Series Resistor
Probe the source voltage on the left side of the series limiting resistor.
Probe the TVS Voltage at the right side of the series limiting resistor.
Clamped Waveform looks marginally correct.
Observation of source waveform:
The waveform starts at 28V, rises to 80V Pulse, returns to 28V, starts identical cycle. Correct
Observation of TVS waveform:
The waveform starts at 28V, rises to 64V Pulse, returns to 28V, starts identical cycle. The waveform fall below 24V (the <24V is not correct).
Change the 100m resistor to 100 Ohms.
Run the simulation again with the 100 Ohm Resistor
Clamped Waveform looks is wrong
Observation of source waveform:
The waveform starts at 0V, rises to 80V Pulse, returns to 28V, starts identical cycle. Correct
Observation of TVS waveform:
The waveform starts at 0.93V, rises to 1.064V Pulse, returns to 0.93V, starts identical cycle. The waveform should loosely follow the previous TVS Waveform above. It doesn¡¯t and appears to be a representation of the clamped current within the TVS device (which is also incorrect ¨C there should be no current flowing through the device). If a 10k Load is placed across the TVS is still does the same thing.
The SMBJ24CA doesn¡¯t have the same behavior. It seems to be much better behaved. Change the Starting Voltage to 15V for that simulation.
Can you check it out ¨C it looks like there is a problem with the SMCJ33A TVS Model.
Thanks,
Ross
From: LTspice@... [mailto:LTspice@...]
Sent: Thursday, July 28, 2016 6:09 PM
To: [LTspice] group
Subject: Re: [LTspice] Re: LTspiceXVII released
"are they gonna call this LTSPICE 17 or LTSPICE 5?"
It seems that they (LTC) or he (Mike) have given it the name LTspice XVII. This program is released. The name is what it is.
By the way, you might want to pay closer attention to the capitalization. Some people get upset when it is done wrong. Neither Mike nor LTC uses "LTSPICE". Also, only two I's in XVII.
"Oh and by the way Helmut, tell mr Mike...I noticed something weird ..."
You should tell him yourself; don't make Helmut do the work for you. Mike shows how to report bugs and other problems. See Help -> About LTspice XVII. (But I am not sure if this one is an LTspice issue or a Wine issue.)
"...just a homeboy here in Fort Worth Texas"
Very much O.T. now -- but I wonder why you posted that link earlier today to a UML (Massachusetts) webpage which didn't have any obvious links to the T.I. patent issue you were describing. Fort Worth and Lowell are very much not local to one another. It just had my curiosity. No big deal.
Andy
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