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LM3488 Spice model won't work on LTspice. Can't also generate in TINA-TI macro wizard

John Roemar Lacson
Prodigy 80 points
Other Parts Discussed in Thread: LM3488, TINA-TI

Hi,

I am trying to simulate a sepic converter using LM3488 controller and I am using LTspice. I added the unencrypted model of it in my LTspice library but when i try to simulate the circuit i create, an error message pops up saying "Syntax error--  Unknown Symbol:ss". I also tried simulating it in TINA-TI but i was not able to find its spice model in TINA-TI library so i tried to add it using the new macro wizard of TINA-TI. I first tried to add the unencrypted model of LM3488 but it shows an error message "Undefined parameter or possible use of a function before definition: SS.". I also tried the encrypted model but i also got an error message saying "Invalid device:$CDNENCSTART. Line: #61."

I'm not familiar with the codes used in spice model so i am out of ideas on how i will fix this error and simulate it on either LTspice or TINA-TI. Please help me in this matter and i want to know why this error occurs.

Thanks. 

  • 0
    TI__Mastermind 41310 points

    John,

    The SS parameter is missing from the .SUBCKT statement in the unencrypted file. Simply change the line:

    .SUBCKT LM3488_TRANS AGND COMP DR FA_SD FB ISEN PGND VIN

    to:

    .SUBCKT LM3488_TRANS AGND COMP DR FA_SD FB ISEN PGND VIN PARAMS: SS=0

    The parameter is used for startup/steady state simulation. Leaving it set at 0 provides the startup simulation. Setting it to 1 would allow you to use initial conditions on your circuit and simulate a steady state simulation.

    I would suggest leaving it at 0 to begin with...

  • 0 in reply to Britt Brooks - Online Design Tools
    Prodigy 80 points
    Hi Mr. Britt Brooks, thank you for answering my question. I followed your instruction and there were no further error in LTspice when i ran my simulation, my only problem now is that my sepic converter circuit does not give any output voltage although i only followed the schematic diagram i got from webench. I am now trying to construct the same circuit to TINA-TI to test if its working or if the problem comes from using LTspice. I will update as soon as i finish the simulation.