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TINA/Spice/UCC28700: PSpice simulation has three initial pulses and some pulses bevor it stops

sterie
Intellectual 340 points
Part Number: UCC28700
Other Parts Discussed in Thread: TINA-TI,

Tool/software: TINA-TI or Spice Models

Hi,

i try to get the Pspice modle UCC28700 running, but i have a problem with the simulation.

After VDD has reached the 22V limit, the DRV pin has 3 initial impulses and after these there are some (mostly 5) pulses again during them i can see the primary side current on the CS pin and also the ringing on the VS pin. Both voltages the CS and VS are inside their limits, but after the 5th pulse no more impulses are generated on the DRV pin. VDD has also a level over 22V.

What can i do wrong, has someone a good idea to get the model running or may be a simple Psice simulation with the UCC28700 already running?

Thank you

Regards

Stefan

  • 0
    TI__Expert 7395 points
    Stefan,
    Thank you for your interest in TI here. I'm sorry to hear that you're having some trouble.
    Can you answer a few questions to help us better understand?:

    1) Can you share your simulation file and details of the type of simulation you are running? (I'm assuming
    a transient sim of some sort but details can help.)
    2) Can you provide waveforms of Vout, Vdd, DRV, CS, and the aux winding of the transformer?
    3) How did you pick the values around the UCC28700? Did you use the excel design calculator from here:
    www.ti.com/.../toolssoftware
    4) In general for any debug on PSR controllers this document can be helpful:
    www.ti.com/.../slua783.pdf

    Regards,
    John