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UCC28700: what are the specifications of Transformer that can be used with UCC28700? Trouble getting the desired output while working with UCC28700 in TINA.

Ashokraj Pilli
Prodigy 210 points
Other Parts Discussed in Thread: UCC28700

Hi, 

     I am trying to design flyback SMPS for an input of 240V and output of 25V, 1.2A. I have used web bench power supply design to generate a circuit. I have created similar circuit in TINA. But I could not able to generate the desired output.

My doubts are the following: 
1. I have used non linear transformer with seperated secondary coils in the circuit. I have kept N primary as 63, N secondary as 11, N aux/ third winding as 9. What are the specifications of transformer I will have to use to simulate a circuit with UCC28700 in TINA ? If in case you have any existing transformer with the configuration mentioned in web bench power supply design please do send me in reply to this. If you do not have, please give me the necessary guidelines for creating a transformer mentioned in the web bench power supply design. 

2.In the reference design of UCC28700 I have noticed a custom made transformer. How can i edit the settings of that transformer to suit my requirements. In the reference design the ouput is 5V. My desired output is 25V, 1.2A.   

3. While I am perfoming transient analysis I am getting various graphs even though I have not mentioned them i.e., Graphs of V_V1, V_U_PM_27, V_MaskGEN. What are these graphs. why are they coming ?  

I have attached my design and Hyper link of web bench power supply design too. 

Thanks,

Ashok. web bench power supply design.pdf

BLDC_SMPS.TSC

  • 0
    TI__Prodigy 590 points

    Hello Ashokraj,

    Your thread has been assigned. You should receive a response within a week.

  • 0 in reply to Pye Naing
    TI__Guru 65885 points

    Hello,

    1. Most of the tools that are available for designing the flyback are 1 to 1.  Both Webench and excel. 
      1. Webench: 
      2. Excel: 
      3. These tools will give you the Np/Na/Ns turns ratio your design requires Ns1 and Ns2.
        1. It is possible to use this tool in your design do one output first with the full power level of both outputs.  This will give you the proper Lpm, Np/Ns/Na primary and peak RMS currents.
        2. To calculate Ns1 and Ns2 adjust your output voltages.  To calculated the winding peak and RMS currents on the secondary outputs adjust the output power for each condition.
        3. Once you have the Np/Ns1/Ns2/Na and RMS currents work with a magnetic manufacture design the transformer.
          1. Keep the leakage inductance to less than 3% and keep the inner winding capacitance as small as possible.
          2. Wurth and Renco have worked design PSR flyback transformers and should be able to help you with the transformer design.
    2. There is an application note for the UCC28700 that you can find at the following link that explains how to select the primary magnetizing inductance and transformer turns ratios. 
    3. I reviewed the graphs that Webench generated and they are calculating estimated power dissipation and currents for various components in the design.  The graphs have titles to what components they are referring too.
    4. In the tina model you need to edit the macro of the transformer to adjust the turns ratio.

    Regards,