Re: Overriding a library diode's internal parameter(s)
On Thu, Apr 10, 2025 at 02:59 PM, Richard Andrews wrote:
Well defining it twice is no good.
Actually, defining something twice (or more) is usually OK in most SPICE programs.? I think it was designed to work that way.
?
In LTspice, sometimes you get a warning message, sometimes not.? And in newer versions, sometimes now it aborts, which could be considered either good or bad.
?
Andy
?
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Re: Overriding a library diode's internal parameter(s)
On Thu, Apr 10, 2025 at 01:59 PM, Bell, Dave wrote:
The diode¡¯s parameter string includes ¡°rs=0.0384¡±, and I want to vary that to adjust the curve to the panel I want to simulate.
FYI, another way you can do that, which might work reasonably well, is this:
- Edit the .MODEL command to make its Rs=0.
- Add a discrete resistor in series with the diode, with resistance = Rs.
There might be some advantage to doing it this way, e.g., if the value of Rs needs to vary.? If it is inside the .MODEL definition, it can't.? If it is an external resistor, it could.
?
Andy
?
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Re: Overriding a library diode's internal parameter(s)
On Thu, Apr 10, 2025 at 01:59 PM, Bell, Dave wrote:
I imagine I could use a default ¡°D¡± diode and modify all of the params, but I don¡¯t see any way to copy the LONG string listed in ¡°Pick new diode¡±.
When you use "Pick New Diode", you select from the diodes in your standard.dio (and/or user.dio).? Therefore, open standard.dio in Notepad/Wordpad or your editor of choice, or in LTspice itself.? Find the line, highlight it, and Ctrl-C (copy).? Be careful not to save the file standard.dio when you're done.
?
The diode¡¯s parameter string includes ¡°rs=0.0384¡±, and I want to vary that to adjust the curve to the panel I want to simulate.
The model adds a multiplier to the diode, ¡°N=15¡±, which I successfully changed to ¡°N={Ns}¡± so I could vary the number of cells.
I tried adding an override of rs by ¡°N={N} Rs={Rser}¡±, but the second term throws an ¡°unrecognized¡± fault.
Right-clicking the diode symbol doesn¡¯t offer any route to setting any terms.
Be careful here.? You are mixing up your parameters.
?
Rs is a .MODEL parameter.? It can be changed only by editing the .MODEL statement.? You can use AKO: or you can replicate the entire .MODEL statement, but it must be done only with the .MODEL statement.? Like all .MODEL parameters, the Rs parameter never comes up in an Attribute of a symbol.? You can't do it that way.
?
N, as you've used it here (as N sets of series-connected diodes) is an element parameter.? It can be changed only in the element line, the one that begins with a "D".? That can be done on an Attribute line of a symbol, because the symbol with its attributes create the D diode element statement.??Do not attempt to modify the N that is a .MODEL parameter because it is not the same thing; and anyway that would not be the right place to change element parameters.
?
Clearly, these two parameters must not be modified the same way as each other.? .MODEL parameters, and element parameters.? Two completely independent things.
?
Andy
?
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Re: Overriding a library diode's internal parameter(s)
I have to think on that, Andy!
?
Please see the file AD_PV_Sim 250410.zip I just uploaded.
?
Dave
?
toggle quoted message
Show quoted text
From: [email protected] <[email protected]>
On Behalf Of Andy I via groups.io
Sent: Thursday, April 10, 2025 12:10 PM
To: [email protected]
Subject: EXTERNAL: Re: [LTspice] Overriding a library diode's internal parameter(s)
?
Be careful with diode parameter 'N'.
'N' in the .model statement means Emission Coefficient.
'N' in the diode element line is the diode multiplier.
This is a SPICE thing that the UCal/Berkeley guys got wrong.
Now back to your regularly scheduled program.
|
Re: Overriding a library diode's internal parameter(s)
Ah, that would means that LTspice XVII doesn't
recognize rs as a parameter of a diode, which cannot be true.
Can you try another diode, just to see if you get the same
error? You could also upload your.ASC and associated files in a
.ZIP.
On 2025-04-10 19:44, Bell, Dave via
groups.io wrote:
OK, correcting my
confusings¡
?
N={Ns} was a typo;
I have N={N}, and that ¨C by itself ¨C works correctly.
It¡¯s the second
parameter, rs={Rs} that causes a fault:
Error on line 3
: d1 vpv 0 mur460 n= 14.9? rs= 0.0384
??????????????
?Unknown parameter "rs"
0.0384 is the
default value (from the Pick New displayed string), so the
value can¡¯t be a problem.
LTspice (XVII)
just rejects the ¡°rs¡±
?
?
Hello,
Richard. I'm not running the sim, that is Dave Bell. I think
N={N} is wrong because there is already N={Ns}; it can't be
defined twice.
On 2025-04-10 19:15, Richard Andrews via
groups.io wrote:
Not
that it matters, but N={N} Rs={Rser} looks right to
me. What version of LTspice are you running? What
exactly does the log file say?
On
Thursday, April 10, 2025 at 02:09:24 PM EDT, John
Woodgate
<jmw@...>
wrote:
I
don't understand this line:
I
tried adding an override of rs by ¡°N={N}
Rs={Rser}¡±,
What
is N={N} for? I don't think you need it: Rs is
in every instance of the diode already. Do you
have a line Rser= [a number], or perhaps a
.STEPped sequence?
On
2025-04-10 18:59, Bell, Dave via groups.io
wrote:
I
was working with the recently linked AD PV
Cell sim.
?
It
uses a MUR460 library diode, multiple in
series, to simulate the cell/string¡¯s
forward voltage.
The
default series resistance seems too high,
per plotted I/V curve.
?
The
diode¡¯s parameter string includes
¡°rs=0.0384¡±, and I want to vary that to
adjust the curve to the panel I want to
simulate.
The
model adds a multiplier to the diode,
¡°N=15¡±, which I successfully changed to
¡°N={Ns}¡± so I could vary the number of
cells.
I
tried adding an override of rs by ¡°N={N}
Rs={Rser}¡±, but the second term throws an
¡°unrecognized¡± fault.
Right-clicking
the diode symbol doesn¡¯t offer any route to
setting any terms.
?
I
imagine I could use a default ¡°D¡± diode and
modify
all of the params, but I don¡¯t see
any way to copy the LONG string listed in
¡°Pick new diode¡±.
?
Is
there a better (i.e. working) way to
override the internal params?
?
Thanks,
Dave
--
Best wishes John Woodgate RAYLEIGH Essex
OOO-Own Opinions Only If something is true:
* as far as we know - it's science *for
certain - it's mathematics *unquestionably -
it's religion
--
Best wishes John Woodgate RAYLEIGH Essex OOO-Own Opinions
Only If something is true: * as far as we
know - it's science *for certain - it's mathematics
*unquestionably - it's religion
--
Best wishes John Woodgate RAYLEIGH Essex OOO-Own Opinions Only
If something is true: * as far as we know - it's science *for
certain - it's mathematics *unquestionably - it's religion
|
Re: Overriding a library diode's internal parameter(s)
In case it matters, ...
?
Be careful with diode parameter 'N'.
?
'N' in the .model statement means Emission Coefficient.
?
'N' in the diode element line is the diode multiplier.
?
This is a SPICE thing that the UCal/Berkeley guys got wrong.
?
Now back to your regularly scheduled program.
?
Andy
|
Re: How to simulate the gate charge characteristic given in the datasheet of a mosfet?
On Wed, Apr 9, 2025 at 02:50 PM, <ankitk.ace@...> wrote:
Amidst all the discussion I overlooked some of the key concepts that are essential to these simulations and I can certainly use a second opinion from you.
Ankit,
?
I will try to address your questions.?
?
3) All measurements made by the .meas statements are done after the simulation has ended. They are done by a post processing step and have access to all signals throughout the simulation.
?
4) The simulation results will be good if the models are good. Actual hardware measurements always have variations due to component tolerances. Unless you repeat your hardware measurements with multiple devices from different production batches you will be measuring only a single part whose parameters could be anywhere within the tolerances shown on the parts datasheets.?
?
1 and 2) The double pulse test is a way to measure the turn on and turn off characteristics of a device with a known on-state load current and known off-state withstand voltage. In a double pulse test the inductor current is ramped up during the first pulse to a known value by controlling the first pulse width. The device under test is then turned off and the on to off behavior of the device can be measured at that current. During the off time the inductor current remains nearly constant because there is only the low voltage across the forward biased upper device body diode across the inductor to reduce the current. Then the device under test is turned on again during the second pulse and the off to on behavior of the device can be measured during this transition. During these tests the inductor is basically performing the function of the constant current limiter in my circuits. Because the device under test is used to set the inductor current, the turn off transition is measured first at the end of the first pulse. Then the turn on transition is measured second when the device under test is turned back on at the beginning of the second pulse. Using an identical device for the upper device in the double pulse test circuit allows you to measure the characteristics of the body diode of those devices. That body diode turns on at the transition at the end of the first pulse, and it turns off at the transition at the beginning of the second pulse.?
Both methods can be used in simulation, but the classic double pulse test circuit is more applicable to real hardware measurements because it does not need ideal diodes or current sources. A charged inductor is a very good approximation of an ideal current source, which is why it is used for the double pulse test. The known drain voltage is applied to the inductor for a fixed time (the width of the first pulse) to charge the inductor up to a known current level. For the remained of the test that current remains nearly constant at that value.
?
HTH
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Re: Overriding a library diode's internal parameter(s)
Well defining it twice is no good.
|
Re: How can I create a continuously (kind of) varying duty cycle in one simulation
I absolutely LOVE the TimerBlox line!
SO many components rolled into one ddevice¡
?
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Show quoted text
From: [email protected] <[email protected]>
On Behalf Of PK
Sent: Thursday, April 10, 2025 11:41 AM
To: [email protected]
Subject: EXTERNAL: Re: [LTspice] How can I create a continuously (kind of) varying duty cycle in one simulation
?
Answer: Use LTC6992 Voltage Controlled PWM
--
PKa?
|
Re: Overriding a library diode's internal parameter(s)
OK, correcting my confusings¡
?
N={Ns} was a typo; I have N={N}, and that ¨C by itself ¨C works correctly.
It¡¯s the second parameter, rs={Rs} that causes a fault:
Error on line 3 : d1 vpv 0 mur460 n= 14.9? rs= 0.0384
?????????????? ?Unknown parameter "rs"
0.0384 is the default value (from the Pick New displayed string), so the
value can¡¯t be a problem.
LTspice (XVII) just rejects the ¡°rs¡±
?
toggle quoted message
Show quoted text
From: [email protected] <[email protected]>
On Behalf Of John Woodgate
Sent: Thursday, April 10, 2025 11:20 AM
To: [email protected]
Subject: EXTERNAL: Re: [LTspice] Overriding a library diode's internal parameter(s)
?
Hello, Richard. I'm not running the sim, that is Dave Bell. I think N={N} is wrong because there is already N={Ns}; it can't be defined twice.
On 2025-04-10 19:15, Richard Andrews via groups.io wrote:
Not that it matters, but N={N} Rs={Rser} looks right to me. What version of LTspice are you running? What exactly does the log file say?
On Thursday, April 10, 2025 at 02:09:24 PM EDT, John Woodgate
<jmw@...> wrote:
I don't understand this line:
I tried adding an override of rs by ¡°N={N} Rs={Rser}¡±,
What is N={N} for? I don't think you need it: Rs is in every instance of the diode already. Do you have a line Rser= [a number], or perhaps a .STEPped sequence?
On 2025-04-10 18:59, Bell, Dave via groups.io wrote:
I was working with the recently linked AD PV Cell sim.
?
It uses a MUR460 library diode, multiple in series, to simulate the cell/string¡¯s forward voltage.
The default series resistance seems too high, per plotted I/V curve.
?
The diode¡¯s parameter string includes ¡°rs=0.0384¡±, and I want to vary that to adjust the curve to the panel I want to simulate.
The model adds a multiplier to the diode, ¡°N=15¡±, which I successfully changed to ¡°N={Ns}¡± so I could vary the number of cells.
I tried adding an override of rs by ¡°N={N} Rs={Rser}¡±, but the second term throws an ¡°unrecognized¡± fault.
Right-clicking the diode symbol doesn¡¯t offer any route to setting any terms.
?
I imagine I could use a default ¡°D¡± diode and modify
all of the params, but I don¡¯t see any way to copy the LONG string listed in ¡°Pick new diode¡±.
?
Is there a better (i.e. working) way to override the internal params?
?
Thanks,
Dave
--
Best wishes John Woodgate RAYLEIGH Essex OOO-Own Opinions Only If something is true: * as far as we know - it's science *for certain - it's mathematics *unquestionably - it's religion
--
Best wishes John Woodgate RAYLEIGH Essex OOO-Own Opinions Only If something is true: * as far as we know - it's science *for certain - it's mathematics *unquestionably - it's religion
|
Re: How can I create a continuously (kind of) varying duty cycle in one simulation
Answer: Use LTC6992 Voltage Controlled PWM
-- PKa?
|
Re: Overriding a library diode's internal parameter(s)
Hello, Richard. I'm not running the sim, that
is Dave Bell. I think N={N} is wrong because there is already
N={Ns}; it can't be defined twice.
On 2025-04-10 19:15, Richard Andrews
via groups.io wrote:
Hello John,
Not that it matters, but N={N}
Rs={Rser} looks right to me. What version of LTspice
are you running? What exactly does the log file say?
On Thursday, April 10, 2025 at 02:09:24 PM EDT, John
Woodgate <jmw@...> wrote:
I don't understand this line:
I tried adding an override of rs by ¡°N={N}
Rs={Rser}¡±,
What is N={N} for? I don't think you need it: Rs is
in every instance of the diode already. Do you have
a line Rser= [a number], or perhaps a .STEPped
sequence?
On
2025-04-10 18:59, Bell, Dave via groups.io wrote:
I was
working with the recently linked AD PV Cell sim.
?
It uses
a MUR460 library diode, multiple in series, to
simulate the cell/string¡¯s forward voltage.
The
default series resistance seems too high, per
plotted I/V curve.
?
The
diode¡¯s parameter string includes ¡°rs=0.0384¡±, and
I want to vary that to adjust the curve to the
panel I want to simulate.
The
model adds a multiplier to the diode, ¡°N=15¡±,
which I successfully changed to ¡°N={Ns}¡± so I
could vary the number of cells.
I tried
adding an override of rs by ¡°N={N} Rs={Rser}¡±, but
the second term throws an ¡°unrecognized¡± fault.
Right-clicking
the diode symbol doesn¡¯t offer any route to
setting any terms.
?
I
imagine I could use a default ¡°D¡± diode and modify
all of the params, but I don¡¯t see any way
to copy the LONG string listed in ¡°Pick new
diode¡±.
?
Is
there a better (i.e. working) way to override the
internal params?
?
Thanks,
Dave
--
Best wishes John Woodgate RAYLEIGH Essex OOO-Own
Opinions Only
If something is true: * as far as we know - it's
science *for certain - it's mathematics
*unquestionably - it's religion
--
Best wishes John Woodgate RAYLEIGH Essex OOO-Own Opinions Only
If something is true: * as far as we know - it's science *for
certain - it's mathematics *unquestionably - it's religion
|
Re: Overriding a library diode's internal parameter(s)
Hello John,
Not that it matters, but N={N}
Rs={Rser} looks right to me. What version of LTspice are you running? What exactly does the log file say?
On Thursday, April 10, 2025 at 02:09:24 PM EDT, John Woodgate <jmw@...> wrote:
I don't understand this line:
I tried adding an override of rs by ¡°N={N} Rs={Rser}¡±,
What is N={N} for? I don't think you need it: Rs is in every
instance of the diode already. Do you have a line Rser= [a
number], or perhaps a .STEPped sequence?
On 2025-04-10 18:59, Bell, Dave via
groups.io wrote:
I was working with the recently linked AD
PV Cell sim.
?
It uses a MUR460 library diode, multiple in
series, to simulate the cell/string¡¯s forward voltage.
The default series resistance seems too
high, per plotted I/V curve.
?
The diode¡¯s parameter string includes
¡°rs=0.0384¡±, and I want to vary that to adjust the curve to
the panel I want to simulate.
The model adds a multiplier to the diode,
¡°N=15¡±, which I successfully changed to ¡°N={Ns}¡± so I could
vary the number of cells.
I tried adding an override of rs by ¡°N={N}
Rs={Rser}¡±, but the second term throws an ¡°unrecognized¡±
fault.
Right-clicking the diode symbol doesn¡¯t
offer any route to setting any terms.
?
I imagine I could use a default ¡°D¡± diode
and modify all of the params, but I don¡¯t see any way
to copy the LONG string listed in ¡°Pick new diode¡±.
?
Is there a better (i.e. working) way to
override the internal params?
?
Thanks,
Dave
--
Best wishes John Woodgate RAYLEIGH Essex OOO-Own Opinions Only
If something is true: * as far as we know - it's science *for
certain - it's mathematics *unquestionably - it's religion
|
Re: Overriding a library diode's internal parameter(s)
I don't understand this line:
I tried adding an override of rs by ¡°N={N} Rs={Rser}¡±,
What is N={N} for? I don't think you need it: Rs is in every
instance of the diode already. Do you have a line Rser= [a
number], or perhaps a .STEPped sequence?
On 2025-04-10 18:59, Bell, Dave via
groups.io wrote:
I was working with the recently linked AD
PV Cell sim.
?
It uses a MUR460 library diode, multiple in
series, to simulate the cell/string¡¯s forward voltage.
The default series resistance seems too
high, per plotted I/V curve.
?
The diode¡¯s parameter string includes
¡°rs=0.0384¡±, and I want to vary that to adjust the curve to
the panel I want to simulate.
The model adds a multiplier to the diode,
¡°N=15¡±, which I successfully changed to ¡°N={Ns}¡± so I could
vary the number of cells.
I tried adding an override of rs by ¡°N={N}
Rs={Rser}¡±, but the second term throws an ¡°unrecognized¡±
fault.
Right-clicking the diode symbol doesn¡¯t
offer any route to setting any terms.
?
I imagine I could use a default ¡°D¡± diode
and modify all of the params, but I don¡¯t see any way
to copy the LONG string listed in ¡°Pick new diode¡±.
?
Is there a better (i.e. working) way to
override the internal params?
?
Thanks,
Dave
--
Best wishes John Woodgate RAYLEIGH Essex OOO-Own Opinions Only
If something is true: * as far as we know - it's science *for
certain - it's mathematics *unquestionably - it's religion
|
Overriding a library diode's internal parameter(s)
I was working with the recently linked AD PV Cell sim.
?
It uses a MUR460 library diode, multiple in series, to simulate the cell/string¡¯s forward voltage.
The default series resistance seems too high, per plotted I/V curve.
?
The diode¡¯s parameter string includes ¡°rs=0.0384¡±, and I want to vary that to adjust the curve to the panel I want to simulate.
The model adds a multiplier to the diode, ¡°N=15¡±, which I successfully changed to ¡°N={Ns}¡± so I could vary the number of cells.
I tried adding an override of rs by ¡°N={N} Rs={Rser}¡±, but the second term throws an ¡°unrecognized¡± fault.
Right-clicking the diode symbol doesn¡¯t offer any route to setting any terms.
?
I imagine I could use a default ¡°D¡± diode and modify all of the params, but I don¡¯t see any way to copy the LONG string listed in ¡°Pick new diode¡±.
?
Is there a better (i.e. working) way to override the internal params?
?
Thanks,
Dave
|
Re: Classic Menu vs Keyboard shortcuts
See this post on ADI's EZone: https://ez.analog.com/design-tools-and-calculators/ltspice/f/q-a/577705/i-would-like-to-use-the-legacy-pre-ltspice-24-ltspice-gui
|
I get "timestep too small".
?
Is that NOT the error you see?
Andy
?
|
Re: Lateral PNP In Model of 741 Internal Architecture
Hi Andy,
?
Thanks for the suggestion - I'll take a look at that example and the built-in LPNP model.
Your point about the antiquity of the device is well-taken. I'm working on learning some more in-depth analog design and the 741 seemed like a good foundational block given how widely documented it is, and then able to use that to move into more advanced/modern circuits.
|
Trying to get this opamp model to work. I keep getting errors. I know it has to do with the "TABLE" lines, but not sure how to fix. Model was pulled from OnSemi's website.
?
File is posted in the temp section as NCS2001_test.zip
|
Re: How can I create a continuously (kind of) varying duty cycle in one simulation
On Wed, Apr 9, 2025 at 04:47 PM, <kmesne@...> wrote:
I am trying to create a duty cycle that kind of continuously varying like in a 200ms simulation I want a duty cycle start from 0.01 to 0.99 ?(approximately 0.01 Duty increase per 2 ms). How can I do this I am really struggling with it .?
If I were to do this, I would use something like the one suggested by Donald.? I prefer it because I think it is easy to visualize how it gives you the? varying duty cycle, and it might be close to how you would build it in hardware.? But I have two differences from Donald's example:
?
(1)? Donald's example (DutyCycleModulator.zip) needs a Maximum Timestep.? Without it, it works but LTspice uses far too few timepoints to get good signal edges.
.tran 0 200m 0 10u
.options plotwinsize=0? ?; <-- Disables waveform compression
?
(2)? Instead of Donald's voltage-controlled switch S1, I would use a comparator, to compare the voltage ramp with the triangle or sawtooth wave.? LTspice's "diffschmitt" element works well for this, even if you omit the hysteresis of the Schmitt function.
?
I uploaded an example, VaryingDutyCycle.asc, in the Temp folder.
?
Andy
?
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Bell, Dave
John Woodgate
DerekK