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Two phase interleaved BUCK topology IC

qingfeng
Prodigy 60 points
Other Parts Discussed in Thread: UCC28220, LM5145

Dear,

     I have one non-isolated DC/DC project which needs to choose the proper controller IC. The spec. is:Input:18~36V,Ouput:15V/45A. So the topology could be single BUCK or two phase interleaved BUCK. From the thermal consideration, two phase BUCK may be more suitable. I don't know whether two phase BUCK using two independent IC or one IC which has two phase function is better? Could you please recommend the proper IC or solutions from your side. Here the foot package of TSSOP is prefer.
    In additon, i have one question to the BUCK IC definiton of Iout(max). Is the value of Iout(max) determined by the external Mosfet driver loss? Can we choose the smaller Iout(max)  if we use external driver circuit?  Does it mean the output current must be smaller than the Iout(max) defined in the quick search website. Can we use two IC which Iout(max) is 20A or one IC which Iout(max) is 40A for the application of 45A of output current in our spec.?
Look forward to your reply. Thank you very muck.

 

  • 0
    TI__Mastermind 34465 points

    Hello Qingfeng,

    You should consider using the UCC28220 dual interleaved PWM controller.
    This can be used in a  dual buck topology and is available in a 16 pin TSSOP or SOIC package.

    Your total output power is 675W and so each of the buck stages needs to be designed to supply about 340W.
    The current rating for each output stage is 23A

    You should download the TI power stage designer and this will guide you with the design of each of the buck stages

    Regards

    John

  • 0 in reply to John Griffin1
    Prodigy 60 points
    Ok. I will study this IC, and feedback to you if I have any questions. Thanks a lot!
  • 0 in reply to John Griffin1
    Prodigy 60 points
    Dear，
    As seen from TI website, LM5145 may be suitable as the current capacity Iout(Max) is 30A and input/output voltage is OK too, here not considering the package . If we use two phase interleaved BUCK, then the output current of one phase is 25A (considering the ocp) as to our spec.(Input:18~36V,Ouput:15V/45A). Here, I have confused that the maximum Iout(Max) is 20A in WEBENCH Designer. Can we use it for 25A output current?
    Moreover, if we use external driver circuit for MOSFET, can the output current be larger than Iout(Max) defined in the IC spec?
    Thank you!

    BR/Qingfeng
  • 0 in reply to qingfeng
    TI__Mastermind 34465 points
    Hello Br,
    The LM5145 is a single stage synchronous buck controller
    Yes you can use the it in your application.
    You just need to ensure that the power components (Mosfets, inductor, capacitors) are rated properly.
    There is a calculator tool available for this part and it will guide you in your design
    Regards
    John
  • 0 in reply to John Griffin1
    Prodigy 60 points
    Dear John，
    LM5145 has two pins of syncout and syncin, which can be easily designed to
    operate two controllers at the same frequency with 180° interleaved. Also, the driver can use the IC driver pin, so the external circuit is very simple. Thank you for your reply.
    BR/qingfeng