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"Physical" PTC model

 

Hello to the community,
I'm very interested by the "PTC Thermistors Physical model" found in
and I have two questions about it.
?
1) When I try to simulate the example ptc_veijola2.asc it throw me several errors:
LTspice 24.0.12 for Windows
Circuit: * C:\users\pascal\xxx\ptc_veijola2.asc
Start Time: Sat Mar 15 18:34:27 2025
Questionable use of curly braces in "begb 0 egb ?i={1/(1/{emax}+0.5*(1+tanh((v(tptc)-{ts})/{c})))}"
? ? Error: undefined symbol in: "1/(1/(emax)+0.5*(1+tanh(([v](tptc)-(ts))/(c))))"
solver = Alternate
Maximum thread count: 8
tnom = 27
temp = 27
method = modified trap
ERROR: Node U1:N003 is floating and connected to current source B:U1:V
Total elapsed time: 0.575 seconds.
Can you help me with that ?
?
2) I would want to simulate this PTC to "measure" a MOSFET case's temperature. In my case the mosfet have an extra pin that output a voltage proportional to case's temperature.
The above PTC model take the ambient temperature and have a third pin to reflect internal temperature.
Is it possible to add an extra pin to be linked to the mosfet temperature pin ?
?
Thanks a lot in advance,

Pascal
?
 

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I can tell you that the error messages do not mean that there is a problem with the simulation. For example, a node connected only to a current source, which has infinite impedance, appears? not to be connected to anything.

On 2025-03-15 17:53, pilou via groups.io wrote:
Hello to the community,
I'm very interested by the "PTC Thermistors Physical model" found in
and I have two questions about it.
?
1) When I try to simulate the example ptc_veijola2.asc it throw me several errors:
LTspice 24.0.12 for Windows
Circuit: * C:\users\pascal\xxx\ptc_veijola2.asc
Start Time: Sat Mar 15 18:34:27 2025
Questionable use of curly braces in "begb 0 egb ?i={1/(1/{emax}+0.5*(1+tanh((v(tptc)-{ts})/{c})))}"
? ? Error: undefined symbol in: "1/(1/(emax)+0.5*(1+tanh(([v](tptc)-(ts))/(c))))"
solver = Alternate
Maximum thread count: 8
tnom = 27
temp = 27
method = modified trap
ERROR: Node U1:N003 is floating and connected to current source B:U1:V
Total elapsed time: 0.575 seconds.
Can you help me with that ?
?
2) I would want to simulate this PTC to "measure" a MOSFET case's temperature. In my case the mosfet have an extra pin that output a voltage proportional to case's temperature.
The above PTC model take the ambient temperature and have a third pin to reflect internal temperature.
Is it possible to add an extra pin to be linked to the mosfet temperature pin ?
?
Thanks a lot in advance,

Pascal
?
--
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

Virus-free.
 

On Sat, Mar 15, 2025 at 11:07 AM, John Woodgate wrote:
I can tell you that the error messages do not mean that there is a problem with the simulation. For example, a node connected only to a current source, which has infinite impedance, appears? not to be connected to anything.
Hello,
thanks a lot for your reply,
Ok I understand, it seems logical.
But how about the
Error: undefined symbol in: "1/(1/(emax)+0.5*(1+tanh(([v](tptc)-(ts))/(c))))"
?
?
 

Hello,

? ? It's poorly coded. will take time to examine everything.


On Sat, Mar 15, 2025 at 2:15 PM, pilou via groups.io
<pilou@...> wrote:
On Sat, Mar 15, 2025 at 11:07 AM, John Woodgate wrote:
I can tell you that the error messages do not mean that there is a problem with the simulation. For example, a node connected only to a current source, which has infinite impedance, appears? not to be connected to anything.
Hello,
thanks a lot for your reply,
Ok I understand, it seems logical.
But how about the
Error: undefined symbol in: "1/(1/(emax)+0.5*(1+tanh(([v](tptc)-(ts))/(c))))"
?
?
 

开云体育

Perhaps it’s the square brackets in “(摆惫闭(迟辫迟肠)”

?

Dave

?

From: [email protected] <[email protected]> On Behalf Of pilou via groups.io
Sent: Saturday, March 15, 2025 11:16 AM
To: [email protected]
Subject: EXTERNAL: Re: [LTspice] "Physical" PTC model

?

On Sat, Mar 15, 2025 at 11:07 AM, John Woodgate wrote:

I can tell you that the error messages do not mean that there is a problem with the simulation. For example, a node connected only to a current source, which has infinite impedance, appears? not to be connected to anything.

Hello,

thanks a lot for your reply,

Ok I understand, it seems logical.

But how about the

Error: undefined symbol in: "1/(1/(emax)+0.5*(1+tanh(([v](tptc)-(ts))/(c))))"

?

?
 

开云体育

I can't diagnose that, unfortunately.

On 2025-03-15 18:15, pilou via groups.io wrote:
On Sat, Mar 15, 2025 at 11:07 AM, John Woodgate wrote:
I can tell you that the error messages do not mean that there is a problem with the simulation. For example, a node connected only to a current source, which has infinite impedance, appears? not to be connected to anything.
Hello,
thanks a lot for your reply,
Ok I understand, it seems logical.
But how about the
Error: undefined symbol in: "1/(1/(emax)+0.5*(1+tanh(([v](tptc)-(ts))/(c))))"
?
?
--
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

Virus-free.
 

开云体育

Maybe some help, Pascal:

?

I got this to compile and “run” without errors, as below:

First, to fill in some unknown values:

?????????????? .params emax=10 c=5 ts=2

Made a voltage source to create and set a value for node “tptc”

?

Then applying your equation to a behavioral voltage source (BV) in the F2 menu:

?????????????? V={1/(1/(emax)+0.5*(1+tanh((v(tptc)-ts)/c)))}

(This syntax didn’t work with a normal V source.)

?

One set of curly braces surrounding everything that needs to be evaluated at run time.

Removing the square brackets? around “v” in v(tptc)

?

The BV source put out about 902mV, if that makes any sense in your circuit…

?

Dave

?

?

From: [email protected] <[email protected]> On Behalf Of pilou via groups.io
Sent: Saturday, March 15, 2025 11:16 AM
To: [email protected]
Subject: EXTERNAL: Re: [LTspice] "Physical" PTC model

?

On Sat, Mar 15, 2025 at 11:07 AM, John Woodgate wrote:

I can tell you that the error messages do not mean that there is a problem with the simulation. For example, a node connected only to a current source, which has infinite impedance, appears? not to be connected to anything.

Hello,

thanks a lot for your reply,

Ok I understand, it seems logical.

But how about the

Error: undefined symbol in: "1/(1/(emax)+0.5*(1+tanh(([v](tptc)-(ts))/(c))))"

?

?
 

开云体育

Oh, I forgot, you don’t need parentheses around emax, either

?????????????? V={1/(1/emax+0.5*(1+tanh((v(tptc)-ts)/c)))}

?

From: [email protected] <[email protected]> On Behalf Of Bell, Dave via groups.io
Sent: Saturday, March 15, 2025 12:05 PM
To: [email protected]
Subject: EXTERNAL: Re: [LTspice] "Physical" PTC model

?

Maybe some help, Pascal:

?

I got this to compile and “run” without errors, as below:

First, to fill in some unknown values:

?????????????? .params emax=10 c=5 ts=2

Made a voltage source to create and set a value for node “tptc”

?

Then applying your equation to a behavioral voltage source (BV) in the F2 menu:

?????????????? V={1/(1/(emax)+0.5*(1+tanh((v(tptc)-ts)/c)))}

(This syntax didn’t work with a normal V source.)

?

One set of curly braces surrounding everything that needs to be evaluated at run time.

Removing the square brackets? around “v” in v(tptc)

?

The BV source put out about 902mV, if that makes any sense in your circuit…

?

Dave

?

?

From: [email protected] <[email protected]> On Behalf Of pilou via groups.io
Sent: Saturday, March 15, 2025 11:16 AM
To: [email protected]
Subject: EXTERNAL: Re: [LTspice] "Physical" PTC model

?

On Sat, Mar 15, 2025 at 11:07 AM, John Woodgate wrote:

I can tell you that the error messages do not mean that there is a problem with the simulation. For example, a node connected only to a current source, which has infinite impedance, appears? not to be connected to anything.

Hello,

thanks a lot for your reply,

Ok I understand, it seems logical.

But how about the

Error: undefined symbol in: "1/(1/(emax)+0.5*(1+tanh(([v](tptc)-(ts))/(c))))"

?

?
 

Thanks a lot for all your message.
But, excuses me for my ignorance, all theses modification have to be done in the model ?
Sorry but I don't know where.
Maybe can you upload your files ?
Thanks a lot in advance
 

开云体育

We would have a MUCH better idea of exactly where to apply them, if YOU would upload YOUR models.

?

?

From: [email protected] <[email protected]> On Behalf Of pilou via groups.io
Sent: Saturday, March 15, 2025 1:11 PM
To: [email protected]
Subject: EXTERNAL: Re: [LTspice] "Physical" PTC model

?

Thanks a lot for all your message.

But, excuses me for my ignorance, all theses modification have to be done in the model ?

Sorry but I don't know where.

Maybe can you upload your files ?

Thanks a lot in advance
 

开云体育

Take a look at the files I just uploaded to Files/Temp

A simple implementation of what I believe is a corrected form of Pascal's thermal expression,

?

Dave

?

From: [email protected] <[email protected]> On Behalf Of pilou via groups.io
Sent: Saturday, March 15, 2025 1:11 PM
To: [email protected]
Subject: EXTERNAL: Re: [LTspice] "Physical" PTC model

?

Thanks a lot for all your message.

But, excuses me for my ignorance, all theses modification have to be done in the model ?

Sorry but I don't know where.

Maybe can you upload your files ?

Thanks a lot in advance

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