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PMP11107: self driven SR implementation

Kiran Kumar R
Intellectual 275 points

Part Number: PMP11107
Other Parts Discussed in Thread: UCC24612

Hi Team, 

How does the Self driven SR circuit in the PMP11107 design behaves in the discontinuous mode of flyback application.  I am working on the flyback design and tried to implement and simulate the Self driven SR as in PMP11107 for my design but due to DCM mode of operation, the current starts flowing negative after reaching zero before the MOSFET is turned off which should be avoided.  In which mode the flyback converter operates in the PMP11107 design?  

Thank you. 

  • 0
    TI__Intellectual 2530 points

    Hi,

    The synchronous FETs in this design are driven by the main flyback transformer (coupled inductor).  They will be on for the complete 1-D period when the primary FET is off.  This requires operation in CCM to keep the current positive, except at light loads.  At light loads there will be some negative "circulating" current.

    It may be possible to operate in DCM using one of our synchronous FET "ideal diode" controllers, UCC24612, to drive each FET.  I have not tried this, but it should work.  The webpage shows a simple block diagram similar to the PMP11107 schematic.

    https://www.ti.com/product/UCC24612?keyMatch=UCC24612&tisearch=search-everything&usecase=GPN

    Thanks,

    David

  • 0 in reply to David Strasser
    Intellectual 275 points

    Hi David,

    Thanks for your prompt response. 

    My fly back design is for an automotive application. Since I couldn't find any AEC-Q qualified SR controller, I am looking for an alternate method to implement SR using discrete solutions. Please let me if you have any suggestions or reference from TI for implementing Synchronous rectification using discrete method for discontinuous mode. 

    Thank you.