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Help understanding the Spice and LTSpice macro model of opamps.

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Alan0354

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I am using LTSpice for simulation. I downloaded the model for dual opamp MAX44263 from Maxim. That's the only model of that opamp. I tried to include into the simulation program but it will not accept it.

I need to understand the terms in the .txt file so I can get rid of the second opamp and the shut down signal. Can anyone give me a link that explain and create LTSpice model so I can modify the file?

Attached is the original .txt file from MAXIM.

Thanks

Alan
 

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  • MAX44263.txt
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KlausST

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Hi,

but it will not accept it.
I'm sure there is a more helpful error description.

get rid of the second opamp and the shut down signal.
In simulation and in real world you should connect unused inputs to a valid input signal.

Klaus
 

FvM

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The *.txt file is a valid SPICE subcircuit with LTSPICE compatible behavioral souce syntax, it should be accepted by LTSPICE.

You need to connect it to a subcircuit or OP symbol. There's no shutdown signal used in the model as far as I see. If you don't want a dual OP model, yu can connect the OPAMP subcircuit below it.
 

Alan0354

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The *.txt file is a valid SPICE subcircuit with LTSPICE compatible behavioral souce syntax, it should be accepted by LTSPICE.

You need to connect it to a subcircuit or OP symbol. There's no shutdown signal used in the model as far as I see. If you don't want a dual OP model, yu can connect the OPAMP subcircuit below it.

Thanks, I am still very new with LTSpice. All I know is to .include MAX44263, then using opamp2 and change the name to MAX44263. Can you give me some guidance what to do in this case?

Thanks

Alan
 

orbanp

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Hi Alan,

There is some brief help in the LTspice help menu, help topics, under FAQ, and then third party models.

There is also a very active LTspice Yahoo group, you should join up there.
That is the primary support venue for LTspice.

Good luck, Peter
 
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Alan0354

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Hi Alan,

There is some brief help in the LTspice help menu, help topics, under FAQ, and then third party models.

There is also a very active LTspice Yahoo group, you should join up there.
That is the primary support venue for LTspice.

Good luck, Peter

Thanks

I join and posted my question. Now I cannot even find my own post!! That forum is so different.

But anyway, I spent this afternoon reading the netlist file of my schematic to familiarize with the file, I think I know enough to write in netlist file ( stumbling though). Do you know how to open a .sub file in the LTSpice lib/sub? I try to open one and look at the format. I want to see what is the difference.

I want to learn how to write subcircuit files, I did some search in the help, I did not find anything. Do you have any article on creating a subcircuit file?

Thanks
 

orbanp

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Hi Alan,

If you include a .sub file into your circuit with the .lib or .inc directive, LTspice lets you open the file from within. If you right-click on the directive it will have an option to open it. Try it!
But any external text editor would work, as mentioned before.

As for making subcircuits, keep exploring the "Files" section in the yahoo group, there are lots of help, tutorials, and examples in there.
Especially read in the "Files" section, in the "FAQ" folder, the "Symbols_and_models.txt" entry.

As you have noticed, Yahoo has a "new and improved" user interface for some time to the satisfaction of everyone ;-)

Good luck, Peter
 
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Alan0354

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Hi Alan,

If you include a .sub file into your circuit with the .lib or .inc directive, LTspice lets you open the file from within. If you right-click on the directive it will have an option to open it. Try it!
But any external text editor would work, as mentioned before.

As for making subcircuits, keep exploring the "Files" section in the yahoo group, there are lots of help, tutorials, and examples in there.
Especially read in the "Files" section, in the "FAQ" folder, the "Symbols_and_models.txt" entry.

As you have noticed, Yahoo has a "new and improved" user interface for some time to the satisfaction of everyone ;-)

Good luck, Peter

I still have no luck. I open a new file in LTSpice, use op to type .include LT1026.sub, then I go to files/LTC.../lib/sub and clicked LT1026.sub. It said it cannot open binary files.

I tried dragging the LT1024.sub into the schematic, it said the same thing.

I tried changing the .sub to .txt and this is what I got:

<Binary File>

Code:
Z@åÊ|þ1¨à'ï]¦ ðâOˆ¾Ä‡å‹éŽÛÿ^^ªJSùùR—“Ø™ŽñƒÖž¨¨kýý¶èÔبﷶôãf¿æ‚`æ²ðæ›m…ŒUG¯Á†˜Èû+õâ	š²ìsi®ÅTV=Ô°ƒõÇÂ:
i	Ðü>(Öç2u%õS|IDMûø
‘’BjU²a(È
àK¬q2žAŠ]0]
GTFË,ÌT ³TÁµ(pn[je¸Ô)RŸ%×’bo^6 Qζ+
tt=p*7ÊþZæêQ±³T+*SLÅõ4ök;GS™t‚ç¿/ '¯]³‹rCÙ‰ ½ê¿züÃv†%È]ýÕ±÷ÇñÉ¡â²nz£`Óì¿þu*ó¾-Ÿš—K0â4¿òeõØÙgÇrÛQò¦©Ø¡¿Ž)֐‡&HÃ7ˆ^«ÙzgäáÞô4i8±BìÊG€ùbî›ûÇ9ŠfɍŸÝÕ>™É ¾ÖŽ©å`]õÜðŒœa 	àÌ	«¹f½²ïA}Xë¶/–µÌ`HÕ@{À0rìâÍV%¸¢G<ʵw¿SE Òå3žÄEaó˜ã&Ôv¤
vN¶ARÛYªÂ
…4]</¾5\&/WNævhû<uZ¸±~QcV&^OÄ°$ÆÆše=¢‹zZ±#Ì?Ú8»Øº!ê£Ï[²–€ÇíDDÀÕFæ³°ƒÈÇ,’ÀªÙ6/®È]þŒ!£–‚‡OҍÊ'ÝÉ`)Å‹vRÚ”º´ÝƒRWíÑjƆx/ÂLÅ~Þ•ãà_¡€×xYfþßG¶”mƒìÚ@1Ð9ÌïìQÓíRn"©®QŒ†Oá(r‚¼(¡ÒýÁé:]Ý\ìx͍q®@½A4÷n×eHÌZujoÇD"·Eb§tüÑ[äÅ}Fàhbº¼ä…V<
Y@ÆóBnÃkVtO¢Üê

ç¢ZÓõF›J'+a¾SºJ¤ÏsHh^KMR¹nÜÔ}ÿ~\BÁÔ4ü¢ÝSÝØ;&0FV[†£j`ú]š4Ô'•ŽÇ¬¿š«½îµî
6áéžÛžÀþiÿòaO¢ô’Žþ®*"¹,ÙÙÍ…ˆ}g³¼ÀµŸ¯p9° =ß.·RÇÜ‚-¢*ÔYâÚX‡×qAv⻍ið$-’ú)‰œlL‰¡p&“©naÍÑ|‘áá}BÒ‡ñ.:xÒQ ÕápQÙ”`dé¿a–Ë1<âo!›» $çëËV§³’6(kuìÚçFKÎk€Ð}ѯ|zÅvÞ&§í{ÉÊm]’PÊ0`~3	EÏàXF…%R)Ãt~}"X§¨Qe@úmc{þõî!Áÿp÷¢¹dõß‹¤ºq*Qå2ÛÄåª6c9YU¾ ÇŽ¦Y©F¾‰¹}H
þ'ei”ßMåμ罡«‚ÛÖ'ûN’ò‹ä¬8âWÛ2ÌLÞËØyØ<ß{žYÕä®bÂËVá}‡”oíñfº;€sH_¯2.0Ž@‡UÁ,üBÐhã‘ïJˆÚ÷Ý›¡*4}µšz‡³Pýß!ùÞ—ñ0üZ<Vƒ6‹öîüüŽê<µ«5Ú?ÊÏ> 5Bdf )l U1`¿R,bm’tïbtt/
Ђˆ ÉvAKî$^z©‰¿WÎr_ƒŠU:EsW¿ÊA3ÉùV6èNÚ9TP¨šZY."K
³÷è"ÅDb{“&ȱ«ŠŽqMÐ`âÖ'
ºOœBèY‡¬ØESìÑÒªÞ³zëêÒPö‰;¤›åBÎ)³Ò#ýï«ã¢0ü

So I am stuck!!!

Thanks for the info, I'll try with the yahoo group.

Thanks
 

orbanp

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Now you are asking a different question!

The LT1026 is built into LTspice, it is in the PoweProducts directory.
You do not need to include anything!

Press "F2", then go to the "PowerProducts" entry there and you will find it among them.

The reason you got that binary file for the LT1026 subcircuit is because that macromodel is encrypted, it is not in clear text format, so Linear Inc. would protect their intellectual property.

Peter
 

Alan0354

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Now you are asking a different question!

The LT1026 is built into LTspice, it is in the PoweProducts directory.
You do not need to include anything!

Press "F2", then go to the "PowerProducts" entry there and you will find it among them.

The reason you got that binary file for the LT1026 subcircuit is because that macromodel is encrypted, it is not in clear text format, so Linear Inc. would protect their intellectual property.

Peter
Ha ha, my computer don't have F2!!! I tried pushing the top roll key after your suggestion yesterday, it did not work!!!

Bottom line, I want to learn the syntax of the opamp subcircuit. I read the file Maxim sent me, it's not as simple as the netlist file of .asc. I am searching the yahoo group now, still no luck so far.

Thanks
 

orbanp

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Hi Alan,

In schematic capture, if you pull down the "Edit" menu, somewhere in the middle there is a menu item called "Component", the shortcut is F2, the icon is a logic and gate, it gives the library selection. On the top, in the tool bar, there is also the logic and gate icon for selecting the library.
Also look around for LTspice tutorials on the net, there are a few of them around, and those have all these details in them.

Peter
 

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