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    Spice model for TL494

    Hi All,

    I'm working on a design for a SMPS and I wish to use a TL494, mainly because I have a few of them lying around and most designs I have seen seem to use them. I am trying to simulate my design in SIMetrix but I am yet to be able to find a spice model for the TL494. I do have a copy of pspice 9.2 but that seems to only contain the schematic symbol and not the spice model.

    My question/request, Does anybody have or know where I can download a spice model for the TL494.

    Thank you for any help.
    Kenneth

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    Re: Spice model for TL494

    This is a very simple chip. I don't know what you are after to simulate, just the pwm generation stage, the full control loop.

    What I should do is simulating the power stage with some constant duty cysles, to see the ripple in the output, the inductor currents, ...

    If this simulation works like expected, build it with the real components, and force the TL494 to provide also constant duty cycles (potentiometer instead of control circuit). From there move on to some calculated guesses for the control loop components, and look at some step responses to see if it behaves ok. The documentation of the old Unitrode seminars is excellent for this task (http://www.smps.us/Unitrode.html)



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  3. #3
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    Re: Spice model for TL494

    Thanks for your reply,

    Quote Originally Posted by svhb
    This is a very simple chip. I don't know what you are after to simulate, just the pwm generation stage, the full control loop.
    Idealy I would like to simulate the entire circuit, failing that doing it in stages could still work.

    Part of the reason that I wish to simulate the circuit is because I have most if not all of the componants from old PC power supplies that I have lying around. I am looking to redesign the circuit to better suit the project I'm working on. Currently I use an old PC power supply with modified connectors to do the job, but this is messy and will not fit the case I wish to use for the finished project either. The output power is also more than I need although that is not a mayor problem, it does however contain several voltages of which I don't require and this is a waste.

    This is where the simulation comes in handy as I can imput the entire exisiting circuit and confirm the output wave forms with the real thing, I can then remove/modify sections of the circuit and see the effect, with out blowing anything up or causing any harm to myself other than my pride.

    Thanks again
    Kenneth



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