On Wed, 13 May 2015 06:13:26 -0700 (PDT), George Herold
<gherold@teachspin.com> wrote:
>On Tuesday, May 12, 2015 at 8:12:16 PM UTC-4, Tim Williams wrote:
>> "Ralph Barone" <address_is@invalid.invalid> wrote in message
>> news:338871053453128354.323302address_is-invalid.invalid@shawnews...
>> > Perhaps not the right place in the thread to say this, but what problems
>> > would come up if you modelled a varistor as a behavioural current source
>> > with I = k* V^alpha in series with a bulk resistance? I've had pretty
>> > good
>> > luck with that model (just not in SPICE).
>>
>> I've seen that advertised before in appnotes, but it doesn't make sense.
>> There's no physical reason to have a power law in a semiconducting device,
>> and it suggests way more leakage current than there should be (the
>> breakdown region might be softer than an exponential, but there still has
>> to be an exponential leakage tail in there). Perhaps it's just a crude
>> fit to the random breakdown-ESR pattern. In much the same way as 1/f
>> noise (another odd order power law) can be modeled as a stacked chain of
>> noise sources of random bandwidth.
>
>Brownian motion and diffusion can have power laws.
>(I don't know how a varistor really works.)
>
>The "1/f" noise in some HV opamps went as the 2/3rd's power.
>(over several orders of magnitude in frequency...)
>I have no idea where the 2/3 comes from.
>
>George H.
>>
>> SPICE won't appreciate it, because a negative number to a random power is
>> likely to result in some random complex number. You'd at least need
>> abs(V) to start, then put the sign back on the current later. Most of the
>> derivatives all disappear at V=0, which doesn't help.
>>
>> A symmetrical exponential function, like tanh, would probably do a good
>> job, though being a bit too sharp. As John says, connecting some
>> resistors in series with that, then cleaning it up with a few more of
>> different threshold voltages and ESRs, would do; but some may balk at this
>> solution using "too many lines". :)
>>
>> A single-line rendering of that isn't actually possible, because a
>> "resistor in series with an exponential" is a transcendental equation, and
>> has to be solved iteratively by the SPICE engine. Your alternative would
>> be to build a "dulled" tanh function (say, toning down the exponential
>> asymptotes by taking the sqrt or something), but that is also impossible,
>> because the only thing that's "dull" enough to tame an exponential is a
>> log (any polynomial or power law just becomes a constant factor to the
>> exponent). But that simply undoes the exponent entirely, giving flat
>> asymptotes; and doesn't work for negative values (see
>> http://www.wolframalpha.com/input/?i=ln%28tanh%28x%29%29 ).
>>
>> Probably, best would be to sit down with a spreadsheet and plug in curves
>> until it works. There's always boring old polynomials, which are probably
>> quite a good idea in this case -- with the right combination of (complex)
>> poles and zeroes, the function can be odd (= gives opposite current for
>> negative argument) and the asymptotes can be linear or quadratic (linear
>> would make sense in that it's the minimum ESR when all semiconducting
>> grains are conducting). With some tweaking, perhaps a non-geometric
>> polynomial could be built that exhibits realistic leakage current, and
>> approximates the V^alpha asymptote.
>>
>> One can also make polynomials from other polynomials (Chebyshev and other
>> named orthogonal polynomial series are typically better for building
>> curve-fits than just throwing coefficients at a geometric series), or from
>> other functions (e.g., the periodic polynomials in cos^n(phi) and such,
>> useful for harmonic analysis).
>>
>> Tim
>>
>> --
>> Seven Transistor Labs, LLC
>> Electrical Engineering Consultation and Contract Design
>> Website: http://seventransistorlabs.com
The Varistor/MOV is nicely fitted with Hyperbolic functions... just
not my usual TANH... that's best for bounding.
...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: skypeanalog | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
Reply by George Herold●May 13, 20152015-05-13
On Tuesday, May 12, 2015 at 8:12:16 PM UTC-4, Tim Williams wrote:
> "Ralph Barone" <address_is@invalid.invalid> wrote in message
> news:338871053453128354.323302address_is-invalid.invalid@shawnews...
> > Perhaps not the right place in the thread to say this, but what problems
> > would come up if you modelled a varistor as a behavioural current source
> > with I = k* V^alpha in series with a bulk resistance? I've had pretty
> > good
> > luck with that model (just not in SPICE).
>
> I've seen that advertised before in appnotes, but it doesn't make sense.
> There's no physical reason to have a power law in a semiconducting device,
> and it suggests way more leakage current than there should be (the
> breakdown region might be softer than an exponential, but there still has
> to be an exponential leakage tail in there). Perhaps it's just a crude
> fit to the random breakdown-ESR pattern. In much the same way as 1/f
> noise (another odd order power law) can be modeled as a stacked chain of
> noise sources of random bandwidth.
Brownian motion and diffusion can have power laws.
(I don't know how a varistor really works.)
The "1/f" noise in some HV opamps went as the 2/3rd's power.
(over several orders of magnitude in frequency...)
I have no idea where the 2/3 comes from.
George H.
>
> SPICE won't appreciate it, because a negative number to a random power is
> likely to result in some random complex number. You'd at least need
> abs(V) to start, then put the sign back on the current later. Most of the
> derivatives all disappear at V=0, which doesn't help.
>
> A symmetrical exponential function, like tanh, would probably do a good
> job, though being a bit too sharp. As John says, connecting some
> resistors in series with that, then cleaning it up with a few more of
> different threshold voltages and ESRs, would do; but some may balk at this
> solution using "too many lines". :)
>
> A single-line rendering of that isn't actually possible, because a
> "resistor in series with an exponential" is a transcendental equation, and
> has to be solved iteratively by the SPICE engine. Your alternative would
> be to build a "dulled" tanh function (say, toning down the exponential
> asymptotes by taking the sqrt or something), but that is also impossible,
> because the only thing that's "dull" enough to tame an exponential is a
> log (any polynomial or power law just becomes a constant factor to the
> exponent). But that simply undoes the exponent entirely, giving flat
> asymptotes; and doesn't work for negative values (see
> http://www.wolframalpha.com/input/?i=ln%28tanh%28x%29%29 ).
>
> Probably, best would be to sit down with a spreadsheet and plug in curves
> until it works. There's always boring old polynomials, which are probably
> quite a good idea in this case -- with the right combination of (complex)
> poles and zeroes, the function can be odd (= gives opposite current for
> negative argument) and the asymptotes can be linear or quadratic (linear
> would make sense in that it's the minimum ESR when all semiconducting
> grains are conducting). With some tweaking, perhaps a non-geometric
> polynomial could be built that exhibits realistic leakage current, and
> approximates the V^alpha asymptote.
>
> One can also make polynomials from other polynomials (Chebyshev and other
> named orthogonal polynomial series are typically better for building
> curve-fits than just throwing coefficients at a geometric series), or from
> other functions (e.g., the periodic polynomials in cos^n(phi) and such,
> useful for harmonic analysis).
>
> Tim
>
> --
> Seven Transistor Labs, LLC
> Electrical Engineering Consultation and Contract Design
> Website: http://seventransistorlabs.com
> "Ralph Barone" <address_is@invalid.invalid> wrote in message
> news:338871053453128354.323302address_is-invalid.invalid@shawnews...
>> Perhaps not the right place in the thread to say this, but what problems
>> would come up if you modelled a varistor as a behavioural current source
>> with I = k* V^alpha in series with a bulk resistance? I've had pretty
>> good
>> luck with that model (just not in SPICE).
>
> I've seen that advertised before in appnotes, but it doesn't make sense.
> There's no physical reason to have a power law in a semiconducting device,
> and it suggests way more leakage current than there should be (the
> breakdown region might be softer than an exponential, but there still has
> to be an exponential leakage tail in there). Perhaps it's just a crude
> fit to the random breakdown-ESR pattern. In much the same way as 1/f
> noise (another odd order power law) can be modeled as a stacked chain of
> noise sources of random bandwidth.
I can't say whether it makes physical sense, but in the limited research
I've done into the characteristics of metal oxide varistors, the I = k*
V^alpha equation keeps popping up. In the curve matching that I have done
(in Excel, mind you), a bit of series resistance kept the curve from
flattening out too much at high applied voltages, and also made sense in
terms of the bulk resistance of the material (disregarding the grain
boundaries where all the non-linear magic occurs).
> SPICE won't appreciate it, because a negative number to a random power is
> likely to result in some random complex number. You'd at least need
> abs(V) to start, then put the sign back on the current later. Most of the
> derivatives all disappear at V=0, which doesn't help.
Definitely, it would need a bit of a wrapper around it (sign() and abs()
functions) to make it symmetrical. I tend to post from my phone, so
tenseness is rewarded (at least while I'm typing).
> A symmetrical exponential function, like tanh, would probably do a good
> job, though being a bit too sharp. As John says, connecting some
> resistors in series with that, then cleaning it up with a few more of
> different threshold voltages and ESRs, would do; but some may balk at this
> solution using "too many lines". :)
>
> A single-line rendering of that isn't actually possible, because a
> "resistor in series with an exponential" is a transcendental equation, and
> has to be solved iteratively by the SPICE engine. Your alternative would
> be to build a "dulled" tanh function (say, toning down the exponential
> asymptotes by taking the sqrt or something), but that is also impossible,
> because the only thing that's "dull" enough to tame an exponential is a
> log (any polynomial or power law just becomes a constant factor to the
> exponent). But that simply undoes the exponent entirely, giving flat
> asymptotes; and doesn't work for negative values (see
> http://www.wolframalpha.com/input/?i=ln%28tanh%28x%29%29 ).
>
> Probably, best would be to sit down with a spreadsheet and plug in curves
> until it works. There's always boring old polynomials, which are probably
> quite a good idea in this case -- with the right combination of (complex)
> poles and zeroes, the function can be odd (= gives opposite current for
> negative argument) and the asymptotes can be linear or quadratic (linear
> would make sense in that it's the minimum ESR when all semiconducting
> grains are conducting). With some tweaking, perhaps a non-geometric
> polynomial could be built that exhibits realistic leakage current, and
> approximates the V^alpha asymptote.
>
> One can also make polynomials from other polynomials (Chebyshev and other
> named orthogonal polynomial series are typically better for building
> curve-fits than just throwing coefficients at a geometric series), or from
> other functions (e.g., the periodic polynomials in cos^n(phi) and such,
> useful for harmonic analysis).
>
> Tim
Reply by Tim Williams●May 12, 20152015-05-12
"Ralph Barone" <address_is@invalid.invalid> wrote in message
news:338871053453128354.323302address_is-invalid.invalid@shawnews...
> Perhaps not the right place in the thread to say this, but what problems
> would come up if you modelled a varistor as a behavioural current source
> with I = k* V^alpha in series with a bulk resistance? I've had pretty
> good
> luck with that model (just not in SPICE).
I've seen that advertised before in appnotes, but it doesn't make sense.
There's no physical reason to have a power law in a semiconducting device,
and it suggests way more leakage current than there should be (the
breakdown region might be softer than an exponential, but there still has
to be an exponential leakage tail in there). Perhaps it's just a crude
fit to the random breakdown-ESR pattern. In much the same way as 1/f
noise (another odd order power law) can be modeled as a stacked chain of
noise sources of random bandwidth.
SPICE won't appreciate it, because a negative number to a random power is
likely to result in some random complex number. You'd at least need
abs(V) to start, then put the sign back on the current later. Most of the
derivatives all disappear at V=0, which doesn't help.
A symmetrical exponential function, like tanh, would probably do a good
job, though being a bit too sharp. As John says, connecting some
resistors in series with that, then cleaning it up with a few more of
different threshold voltages and ESRs, would do; but some may balk at this
solution using "too many lines". :)
A single-line rendering of that isn't actually possible, because a
"resistor in series with an exponential" is a transcendental equation, and
has to be solved iteratively by the SPICE engine. Your alternative would
be to build a "dulled" tanh function (say, toning down the exponential
asymptotes by taking the sqrt or something), but that is also impossible,
because the only thing that's "dull" enough to tame an exponential is a
log (any polynomial or power law just becomes a constant factor to the
exponent). But that simply undoes the exponent entirely, giving flat
asymptotes; and doesn't work for negative values (see
http://www.wolframalpha.com/input/?i=ln%28tanh%28x%29%29 ).
Probably, best would be to sit down with a spreadsheet and plug in curves
until it works. There's always boring old polynomials, which are probably
quite a good idea in this case -- with the right combination of (complex)
poles and zeroes, the function can be odd (= gives opposite current for
negative argument) and the asymptotes can be linear or quadratic (linear
would make sense in that it's the minimum ESR when all semiconducting
grains are conducting). With some tweaking, perhaps a non-geometric
polynomial could be built that exhibits realistic leakage current, and
approximates the V^alpha asymptote.
One can also make polynomials from other polynomials (Chebyshev and other
named orthogonal polynomial series are typically better for building
curve-fits than just throwing coefficients at a geometric series), or from
other functions (e.g., the periodic polynomials in cos^n(phi) and such,
useful for harmonic analysis).
Tim
--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Contract Design
Website: http://seventransistorlabs.com
Reply by Jim Thompson●May 12, 20152015-05-12
On Tue, 12 May 2015 18:54:48 -0500, "Tim Williams"
<tiwill@seventransistorlabs.com> wrote:
>"Jim Thompson" <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote
>in message news:pg24lati560f9obr5rqcfji0ce8c02h23u@4ax.com...
>>>and if he sees some
>>>examples, maybe he'd even admit what it is, too ;-)
>>>
>>>Tim
>>
>> How about an NCP1072? That was requested on the LTspice List >:-}
>
>http://www.onsemi.com/PowerSolutions/supportDoc.do?type=models&rpn=NCP1072
>
>"Document ID" says it's an "ISpice Model", but extension says it's a
>.DWG.... WTF?
That link is certainly an AutoCAD Drawing (.DWG)
>
>Of course, an IC is something quite a bit more involved than a passive
>two-terminal. It would take time, especially if no good resources are
>available. I wouldn't do that for free (nor would I guess you, either!).
A typical I/C (or hybrid, as I've been doing lately) usually takes me
3-6 weeks.
>
>Tim
There _is_ an ISpice model of the NCP1072 rummaging around, but it
apparently won't run on anything but ISpice. I haven't tried to
decipher its syntax into Berkeley-compliant... yet.
...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: skypeanalog | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
Reply by Tim Williams●May 12, 20152015-05-12
"Jim Thompson" <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote
in message news:pg24lati560f9obr5rqcfji0ce8c02h23u@4ax.com...
>>and if he sees some
>>examples, maybe he'd even admit what it is, too ;-)
>>
>>Tim
>
> How about an NCP1072? That was requested on the LTspice List >:-}
http://www.onsemi.com/PowerSolutions/supportDoc.do?type=models&rpn=NCP1072
"Document ID" says it's an "ISpice Model", but extension says it's a
.DWG.... WTF?
Of course, an IC is something quite a bit more involved than a passive
two-terminal. It would take time, especially if no good resources are
available. I wouldn't do that for free (nor would I guess you, either!).
Tim
--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Contract Design
Website: http://seventransistorlabs.com
Reply by Jim Thompson●May 12, 20152015-05-12
On Tue, 12 May 2015 14:09:16 -0700, John Larkin
<jlarkin@highlandtechnology.com> wrote:
>On Tue, 12 May 2015 13:44:46 -0700, Jim Thompson
><To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:
>
>>On Tue, 12 May 2015 13:40:48 -0700, John Larkin
>><jlarkin@highlandtechnology.com> wrote:
>>
>>>On Tue, 12 May 2015 13:03:03 -0700, Jim Thompson
>>><To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:
>>>
>>>>On Tue, 12 May 2015 12:55:37 -0700, John Larkin
>>>><jlarkin@highlandtechnology.com> wrote:
>>>>
>>>>>On Tue, 12 May 2015 13:03:16 GMT, Ralph Barone
>>>>><address_is@invalid.invalid> wrote:
>>>>>
>>>>>>"Tim Williams" <tiwill@seventransistorlabs.com> wrote:
>>>>>>> "Phil Hobbs" <pcdhSpamMeSenseless@electrooptical.net> wrote in message
>>>>>>> news:55515040.8030806@electrooptical.net...
>>>>>>>> Seems pretty pointless at your age, Jim. Are you ever going to pass on
>>>>>>>> all those pearls of wisdom, or are you going to take them to the grave
>>>>>>>> like King Tut?
>>>>>>>
>>>>>>> On a related note then, if anyone has something they'd like to model, I
>>>>>>> could take a crack at it.
>>>>>>>
>>>>>>> I suspect Jim isn't doing anything I don't know, and if he sees some
>>>>>>> examples, maybe he'd even admit what it is, too ;-)
>>>>>>>
>>>>>>> Tim
>>>>>>
>>>>>>Perhaps not the right place in the thread to say this, but what problems
>>>>>>would come up if you modelled a varistor as a behavioural current source
>>>>>>with I = k* V^alpha in series with a bulk resistance? I've had pretty good
>>>>>>luck with that model (just not in SPICE).
>>>>>
>>>>>The LT Spice "g" componant is a voltage dependant current source. The
>>>>>relationship could be your equation, or a polynomial, or anything.
>>>>>That would be *one* line of text. Add capacitance or ESL as needed.
>>>>
>>>>Yep. The MOV equation is one line of GVALUE... with coefficients set
>>>>by VTEST, ITEST, VCLAMP, ICLAMP, Rseries, Lseries and Cpar, right from
>>>>the data sheet.
>>>
>>>One line? What line? This one maybe?
>>>
>>>1e0b22458c9e013c316e1a17d2fb21f94017955ce88f51ef5c03aab498e88eb5e71f71e1875841719b8947fe3d6f920cb7af1fedfab169c9c17d1a3c4a3fa116
>>
>>You will NEVER see the equation, as simple as it is, NEVER >:-}
>>
>> ...Jim Thompson
>
>Oh no, no, I'm heartbroken.
Good >:-}
...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: skypeanalog | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
Reply by John Larkin●May 12, 20152015-05-12
On Tue, 12 May 2015 13:44:46 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:
>On Tue, 12 May 2015 13:40:48 -0700, John Larkin
><jlarkin@highlandtechnology.com> wrote:
>
>>On Tue, 12 May 2015 13:03:03 -0700, Jim Thompson
>><To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:
>>
>>>On Tue, 12 May 2015 12:55:37 -0700, John Larkin
>>><jlarkin@highlandtechnology.com> wrote:
>>>
>>>>On Tue, 12 May 2015 13:03:16 GMT, Ralph Barone
>>>><address_is@invalid.invalid> wrote:
>>>>
>>>>>"Tim Williams" <tiwill@seventransistorlabs.com> wrote:
>>>>>> "Phil Hobbs" <pcdhSpamMeSenseless@electrooptical.net> wrote in message
>>>>>> news:55515040.8030806@electrooptical.net...
>>>>>>> Seems pretty pointless at your age, Jim. Are you ever going to pass on
>>>>>>> all those pearls of wisdom, or are you going to take them to the grave
>>>>>>> like King Tut?
>>>>>>
>>>>>> On a related note then, if anyone has something they'd like to model, I
>>>>>> could take a crack at it.
>>>>>>
>>>>>> I suspect Jim isn't doing anything I don't know, and if he sees some
>>>>>> examples, maybe he'd even admit what it is, too ;-)
>>>>>>
>>>>>> Tim
>>>>>
>>>>>Perhaps not the right place in the thread to say this, but what problems
>>>>>would come up if you modelled a varistor as a behavioural current source
>>>>>with I = k* V^alpha in series with a bulk resistance? I've had pretty good
>>>>>luck with that model (just not in SPICE).
>>>>
>>>>The LT Spice "g" componant is a voltage dependant current source. The
>>>>relationship could be your equation, or a polynomial, or anything.
>>>>That would be *one* line of text. Add capacitance or ESL as needed.
>>>
>>>Yep. The MOV equation is one line of GVALUE... with coefficients set
>>>by VTEST, ITEST, VCLAMP, ICLAMP, Rseries, Lseries and Cpar, right from
>>>the data sheet.
>>
>>One line? What line? This one maybe?
>>
>>1e0b22458c9e013c316e1a17d2fb21f94017955ce88f51ef5c03aab498e88eb5e71f71e1875841719b8947fe3d6f920cb7af1fedfab169c9c17d1a3c4a3fa116
>
>You will NEVER see the equation, as simple as it is, NEVER >:-}
>
> ...Jim Thompson
Oh no, no, I'm heartbroken.
--
John Larkin Highland Technology, Inc
picosecond timing precision measurement
jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
Reply by Jim Thompson●May 12, 20152015-05-12
On Tue, 12 May 2015 13:40:48 -0700, John Larkin
<jlarkin@highlandtechnology.com> wrote:
>On Tue, 12 May 2015 13:03:03 -0700, Jim Thompson
><To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:
>
>>On Tue, 12 May 2015 12:55:37 -0700, John Larkin
>><jlarkin@highlandtechnology.com> wrote:
>>
>>>On Tue, 12 May 2015 13:03:16 GMT, Ralph Barone
>>><address_is@invalid.invalid> wrote:
>>>
>>>>"Tim Williams" <tiwill@seventransistorlabs.com> wrote:
>>>>> "Phil Hobbs" <pcdhSpamMeSenseless@electrooptical.net> wrote in message
>>>>> news:55515040.8030806@electrooptical.net...
>>>>>> Seems pretty pointless at your age, Jim. Are you ever going to pass on
>>>>>> all those pearls of wisdom, or are you going to take them to the grave
>>>>>> like King Tut?
>>>>>
>>>>> On a related note then, if anyone has something they'd like to model, I
>>>>> could take a crack at it.
>>>>>
>>>>> I suspect Jim isn't doing anything I don't know, and if he sees some
>>>>> examples, maybe he'd even admit what it is, too ;-)
>>>>>
>>>>> Tim
>>>>
>>>>Perhaps not the right place in the thread to say this, but what problems
>>>>would come up if you modelled a varistor as a behavioural current source
>>>>with I = k* V^alpha in series with a bulk resistance? I've had pretty good
>>>>luck with that model (just not in SPICE).
>>>
>>>The LT Spice "g" componant is a voltage dependant current source. The
>>>relationship could be your equation, or a polynomial, or anything.
>>>That would be *one* line of text. Add capacitance or ESL as needed.
>>
>>Yep. The MOV equation is one line of GVALUE... with coefficients set
>>by VTEST, ITEST, VCLAMP, ICLAMP, Rseries, Lseries and Cpar, right from
>>the data sheet.
>
>One line? What line? This one maybe?
>
>1e0b22458c9e013c316e1a17d2fb21f94017955ce88f51ef5c03aab498e88eb5e71f71e1875841719b8947fe3d6f920cb7af1fedfab169c9c17d1a3c4a3fa116
You will NEVER see the equation, as simple as it is, NEVER >:-}
...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: skypeanalog | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
Reply by John Larkin●May 12, 20152015-05-12
On Tue, 12 May 2015 13:03:03 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:
>On Tue, 12 May 2015 12:55:37 -0700, John Larkin
><jlarkin@highlandtechnology.com> wrote:
>
>>On Tue, 12 May 2015 13:03:16 GMT, Ralph Barone
>><address_is@invalid.invalid> wrote:
>>
>>>"Tim Williams" <tiwill@seventransistorlabs.com> wrote:
>>>> "Phil Hobbs" <pcdhSpamMeSenseless@electrooptical.net> wrote in message
>>>> news:55515040.8030806@electrooptical.net...
>>>>> Seems pretty pointless at your age, Jim. Are you ever going to pass on
>>>>> all those pearls of wisdom, or are you going to take them to the grave
>>>>> like King Tut?
>>>>
>>>> On a related note then, if anyone has something they'd like to model, I
>>>> could take a crack at it.
>>>>
>>>> I suspect Jim isn't doing anything I don't know, and if he sees some
>>>> examples, maybe he'd even admit what it is, too ;-)
>>>>
>>>> Tim
>>>
>>>Perhaps not the right place in the thread to say this, but what problems
>>>would come up if you modelled a varistor as a behavioural current source
>>>with I = k* V^alpha in series with a bulk resistance? I've had pretty good
>>>luck with that model (just not in SPICE).
>>
>>The LT Spice "g" componant is a voltage dependant current source. The
>>relationship could be your equation, or a polynomial, or anything.
>>That would be *one* line of text. Add capacitance or ESL as needed.
>
>Yep. The MOV equation is one line of GVALUE... with coefficients set
>by VTEST, ITEST, VCLAMP, ICLAMP, Rseries, Lseries and Cpar, right from
>the data sheet.
One line? What line? This one maybe?
1e0b22458c9e013c316e1a17d2fb21f94017955ce88f51ef5c03aab498e88eb5e71f71e1875841719b8947fe3d6f920cb7af1fedfab169c9c17d1a3c4a3fa116
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John Larkin Highland Technology, Inc
picosecond timing precision measurement
jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com