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Multiphase converter using UCD9224 and UCD 7242

Ashokn
Intellectual 410 points
Other Parts Discussed in Thread: UCD7242, PTD08D210W, UCD9224, UCD74111, UCD74120, UCD7230, PTD08A020W, UCD7411, UCD9246

Hi,

Is it possible to make a 4 phase converter usingthe controller UCD 9224 and UCD 7242 fet? When I try selecting UCD7242 in fusion designer , the power stage shows that both the PWM input as tied together.

1. If not, is there an integrated driver +Fet like UCD7242 tha will support a multiphase configuration.

2. Does any of the Modules (like PTD08D210W ) support a multi phase configuration?

My requirement is

12V to 1V at 40 A , preferrably muliphase

Thanks

Ashok

 

 

  • 0
    TI__Prodigy 180 points

    Hi Ashok,

    UCD9224+UCD7242 can be designed to support 1V/40A application. UCD92xx controller has current sharing function embedded.

    If your design will operate 40A continuously, I suggest you using UCD74111 to replace UCD7242. UCD74111 is rated at 15A and can give you buffer for 40A operation. And UCD72111 has higher efficiency.

    You may also take a look at UCD74120 which is rated at 25A. 2-phase design with UCD74120 may save some board space and external components for you, but the efficiency will not as good as 4-phase design with UCD74111.

    Thank you.

  • 0
    TI__Genius 13700 points

    UCD7242 is not recommended for multiphase application, it is shown in a dual parallel application in the datasheet where both phases are driven from the same DPWM signal.

    UCD74111/UCD74120 are 15A/25A drivers with integrated mosfets which can be used in a multi-phase application.

    PTD08D210W module is based on UCD7242 Driver/Mosfet device and is thus constrained by the same recommendations as the UCD7242.

    PTD08A020W Modules have been used in multiphase applications but maximum switching frequency will be limited to <500KHz due to the minimum on time limitation of the UCD7230 driver used on the module and the 12 to 1 voltage stepdown requirement in your design.

  • 0 in reply to Brad
    Intellectual 410 points

    Thankyou Brad and Carl

    So if UCD7411 supports 15 A, I can meet my requirements using  3 phases. 

    I tried using Phase 1A, 1B and 2 A for rail 1 , and  Fusion designer did not report any error. Do you think its a valid configuration for the UCD9224 controller

    But I did not see any option to specify the phase relation between the 3 channels. Or does the software automatically figures out that its a 3 phase converter?

    I am planning to set a switching frequency to 750KHz, Is there a minmum controllable ON time specification for UCD9224/UCD7411 that I should be aware of? 


    Thanks

    Ashok


  • 0 in reply to Ashokn
    TI__Genius 13700 points

    Yes, 1A, 1B and 2A is valid configuration.  The Phase/Rail configuration section of the Fusion Digital Power Designer SW would warn you if you had selected an invalid rail configuration.  The two main rules for phase/rail selection are that you cannot skip a rail (not possible with the UCD9224 but for the UCD9246 or 9248 which is capable of 4 rails then they must be used in order) and the second rule is that the A and B phases with the same numbered phase cannot be split between two configured rails.

    So in your application with the UCD9224, using 1A, 1B and 2A is valid for a three phase rail and 3A could be used for a second rail, if needed, but if you had used 1A, 2A and 3A which is also valid for a three phase rail then the 1B phase could not be used for a second rail.

    All phases of a multiphase rail will be distributed evenly over the complete switching period automatically by the FW.  The phase/rail config section tells the controller how to setup the phases.

    Minimum on time for the UCD74111 is 50ns, this will be automatically handled if using the default values loaded by the Fusion GUI when selecting the UCD74111.

  • 0 in reply to Brad
    Intellectual 410 points

    Thank You Brad,

    Could you please provide the schematic  for the eval board P6000 based on UCD9224 (Sync Buck(x4), Buck (1V @ 25A) )

    Although TI website lists a schematic, the link takes me to a wrong file (Inspection report)!

    http://www.ti.com/tool/pmp6000.1

    Thanks

    Ashok

     

  • 0 in reply to Ashokn
    TI__Expert 5275 points

    Hi Ashok,

     

    It looks like there was indeed a mismatch between the link and the schematic.  Thanks for bringing this to our attention.  I have attached the PMP6000 schematic for you:

    0005.PMP6000revA_February_16_2011_schematic.pdf

    Action is being taken to correct the link on the website. It should be working in a day or two.

    Let us know if you have any more questions!

     

    Best Regards,

    Adam Hoover

    Analog Centralized Applications Team