This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

PMP20588: Problem with trying to simulate PMP20588

Part Number: PMP20588
Other Parts Discussed in Thread: LM5022,

Good morning,

I'm developing some isolated flyback supplies and I'm using the PMP20588 as a reference.  I actually designed and built up a small board with the reference design (with all of the components under the transformer) for evaluating the LM5022 and it works great, my problem is with the simulation I'm trying to create to use in parallel so that before I design an actual supply I can make some estimates of component power consumption at various loads.  In my simulation, the CS signal goes too high during switching and the duty cycle of the output is cut down as a result.  The output on my board looks great at full load (54V, 600mA), I just can't seem to get the simulation to function as well.  I'm not sure where my problem is, it seems like the current through the FET isn't realistically modeled?  I'm just not sure, I've attached the simulation below.  Thanks for your time!

Kind regards, 

-Steve

30W LM5022 Supply.TSC

  • Hi all,

    Has anyone had any luck with this?  I was really hoping to be able to get this working, but if I can't simulate power supplies with TINA I can always go back to using LTSpice and Linear Tech parts.  We've always simulated our power supplies with LTSpice before building them, TINA and TI would be a nice alternate.  I would have thought someone at TI has a simulation saved somewhere for this reference design.  It's unfortunate because the actual test board I built works really well, the output from the transformer looks as good as it can get.

    Kind regards,

    -Steve

  • Hi Steve,

    Thank you for considering TI product.  We just noticed your post because the LM5022 was not apparent in the thread subject line.  

    We will take a look into this, and get  back to you later.

    Thanks,

    Youhao Xi, Applications Engineering

  • Hi Steve,

    I studied your model for sometime and the problem seems to be the model of the transformer.  You should not use the transformer model but the coupled inductor model.  Your transformer model does not have any inductance, this is why the switch current is so high tripping the peak current limit.  Please change it to the coupled inductor, and specify the primary and secondary inductances instead of the turns ratio.  I just see Tina has two winding coupled inductor.  Use it and remove your third winding circuit for VCC, and just keep the VCC capacitor, and it will simulate.

    Thanks,

    Youhao Xi