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UCC28704: transformer design

HARINI KRISHNA
Expert 1905 points
Part Number: UCC28704

Hi,

We are using UCC28704 as an auxilary supply. We used the webench design tool for the design

12V_AUX_SUPPLY.pdf

Can you tell the part number for the transformer used in the design?

Thank-you

Warm Regards

Harini Krishna

  • 0
    TI__Guru* 85846 points

    Hello Harini,

    Webench gives you the information for core selecting, wire, turns ratio, peak and RMS currents so you can have a custom transformer built.  If you have experience in magnetic design you can do the design your self.  The other option is to send the speciation's to a magnetic design house and have them do the design for you.  You could go to GCI or Wurth and they will design the magnetic for you.

    The other option you have is to search existing transformer manufactures to see if they have a design that meets or exceeds what Webench suggested for the transformer.

    Regards,

  • 0 in reply to Mike O'
    Expert 1905 points

    Hi Mike,

    Thank-you for the reply.

    We are trying to simulate the webench design on Tina TI. 

    along the spice model file we found a spice model for transformer and used the same.

    Is this the correct way to connect the transformer?

    are p1,p2 primary side of the transformer

         s1,s2 secondary side and 

    Rs2 and Rs2 the auxiliary winding at primary?

    after making connections we are observing that for a 325V DC input( we are simulating from the DC stage after the rectifier and filter)

    and observing that that output of the converter is almost zero.

    Vout is the output of the converter and VF1 is the vdd to ucc28704 IC

    Thank-you

    Warm Regards

    Harini Krishna

  • 0 in reply to HARINI KRISHNA
    Expert 1905 points

    Hi,

    How can i simulate the required transformer in the design?

    I see that there is no option for 2 primary windings and 1 secondary winding in tina ti.

    Thank-you

    Warm Regards

    harini krishna

  • 0 in reply to HARINI KRISHNA
    TI__Guru* 85846 points

    Hello Harini,

    I am not sure what the issue is that you are having with using a Spice model in Tina for the UCC28704 in Tina.

    I have heard others have had the same issue.

    There is a transient Pspice model for the UCC28704 that should be a good starting point for your design; as well as, a free version of PSPICE that you can download from TI to evaluate it.  You can find the software at the following web link. www.ti.com/.../PSPICE-FOR-TI FOR TI&tisearch=Search-EN-everything

    I would suggest that you down load the free version of PSpice and start your evaluation with the UCC28704 PSpice Transient model.  The PSpice software also has 1 to 2 transformers that you can you use for evaluatoin.

    Regards,

  • 0 in reply to Mike O'
    Expert 1905 points

    Hi Mike,

    Thank-you for the reply. 

    in the webench design  document transformer windings  are as follows

    Naux= 13

    Naux= 9 

    which one is the main winding and which one is the auxiliary winding at the secondary?

    and where do i find the awg of the wire selected? 

    Thank-you 

    Warm Regards

    harini krishna

  • 0 in reply to HARINI KRISHNA
    TI__Guru* 85846 points

    Hello,

    Naps = Primary to secondary turs ratio = Np/Ns = 104/9

    The second Naux is the secondary winding (9)  and not the aux winding.

    The first Naux is the bias winding.

    Regards,