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UCC256402: Can we use full bridge rectifier circuit at secondary side with UCC256402?

Part Number: UCC256402
Other Parts Discussed in Thread: UCD3138

Hi Team,

Good day.

We received a query from customer support asking for information regarding UCC256402 in full bridge rectifier. For me to not miss any
information, I will copy the quuery below.

The center tapped configuration and it was working fine but then we shifted to full bridge rectification configuration as we wanted to increase output voltage (output rectifier diode's PIV is restricting us to increase the output voltage in center tapped config.). We have not changed anything in the circuit apart from rectification method and ever since we shifted to full bridge method, we have damaged 2 nos of UCC256402 at no load condition (note : we have successfully achieved desired output voltage at no load condition for some time then IC stopped working and after troubleshooting we came to know that high side gate driver section got damaged, DMM is showing 390ohm between HS and HO, 237ohm between HS and HB. both time destruction is in the same section.

Is there any relation between the damage and Full bridge method ?
Do we have to change anything in the circuit if we change the rectification method ?
UCC256402 's design calculator (excel) and datasheet/ EVM guide all these documents consider center tapped configuration so I got confuse whether we can use Full Bridge or not.

Thank you and looking forward for your kind response.

Regards,
Maynard

  • Hello,

    This device was designed for a half bridge.  The C2000 and UCD3138 digital power controllers can do this.

    If you have interest in perusing an LLC H Bridge with these devices, please repost with C2000 and/or UCD3138 in the title so the appropriate applications engineering team can help answer your questions.

    Regards,

      

  • Hi Mike,

    Thank you for the fast response. I just received a reply from our customer and wants to confirm regarding a link from our e2e which mention that "If a full bridge rectification scheme is used, yes the conduction losses would double. ". Again, for me to not miss any information, ill be copying the statement below.

    "As per Mike O', UCC256402 is designed for half bridge but I think he is talking about primary side configuration where I am talking about secondary side rectification method, in primary side I am going to use half bridge LLC but at secondary side I want to use full bridge rectification method.
    If not then what is the meaning of this >>
    e2e.ti.com/.../852958

    Thank you and looking forward for your kind response.

    Regards,
    Maynard

  • Hello Maynard,

    Not sure why you would use full bridge rectification on the outputs.  However, Ben is correct if you use full bridge rectification the conduction losses on the secondary would double.

    Regards,

  • Hi Mike O'

    Thanks for your reply.

    Actually we want to generate 670V output and for that we need diode with at least 1500V PIV but currently we can not find diode with this much PIV at lower cost so for PoC purpose we are using diode with 1000V PIV and for that we need to use full bridge rectification method.

    In this post, once you said that we can not use full bridge rectifier at secondary side with UCC256402 but then in your second reply you are saying that only conduction loss would double , does it meant that we can use  full bridge rectifier at secondary side ??

    Regards,

    Jitendra

  • Hello,

    I thought the design was using a full bridge on the primary and not the secondary.

    You should be able to use a full bridge on the secondary.  However, you will have 2X the losses.

    Regards,

  • Thanks for your reply.

    Do I need to change anything in primary side if I switch to full bridge rectification (sec. Side) or  same circuit will work and only secondary side diode's condition loss would double ?

  • Hello,

    I don't believe that you have to make adjustments on the primary.

    Regards,

    Mike