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TINA/Spice/UC1823: UC1823 Ramp Generation

Jeremy Chambon
Prodigy 140 points
Part Number: UC1823
Other Parts Discussed in Thread: TINA-TI, , UC1825

Tool/software: TINA-TI or Spice Models

Hello,

I'm actually using PSPICE with the encrypted model UC1823. I have a problem with the pin RAMP that generates a sawtooth of 0V to 2.8V instead of 0.8-1V to 2.8V. It seems the Vvalley is not considered in this model and the sawtooth doesn't change at all with a high duty cycle ( > 50%). It's impossible to analyze the impact of the sub-harmonics by using slope compensation because the saw tooth doesn't change at all. Do you know if a UC1823 model has been developed for PSPICE?

Thank you very much,

Jeremy

  • 0
    TI__Genius 9775 points
    Hi Jeremy,

    Did you get the model from certain group inside TI or from FAE representative perhaps?

    I could not locate this model from any of our system especially under the "Tools & Software" section of the product as shown here www.ti.com/.../UC1823

    Due to this, I am having difficulties to comment on your question. It's best if you contact the person that provides you with the model. If you receive the model through email, perhaps reply back to the email by which you have received the model to begin with sot that those folks can retrace back the creator of the model.

    Herman
  • 0 in reply to Herman Theodorus
    Prodigy 140 points
    Hello Herman,

    Thank you for your quick reply. The model comes from PSPICE Library. I'm actually contacting them to discuss about the model.

    Hovewer, I have installed TINA to use the UC1825 model. Could i use this model to have the same behavior of the UC1823 or UC1823-SP?

    I would like to know if the RT and CT pins of the UC1825 define the same frequency as the UC1823 and the UC1823-SP? For example, if I choose RT = 1.5k and CT = 470pf (www.ti.com/.../uc1825.pdf), i have around 1.5MHz. Should I get the same frequency for UC1823, UC1823(A)-SP or UC1823-SP?

    Thank you very much,
    Jeremy
  • 0 in reply to Jeremy Chambon
    TI__Genius 9775 points
    Hi Jeremy,

    Since we don't create the model, it is difficult for us to answer some of your questions. You can give it a try and see if let's say using UC1823 in TINA-TI will give the right response. My guess is that it will given that there is no special component used in OrCad that cannot be executed in TINA-TI.

    If you want further questions, it needs to be directed to OrCad (the model creator) and/or TINA vendor which is DesignSoft. You can inquiry it directly through https://www.tina.com/ support section.

    Herman