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TPS7H5001-SP: Synchronous Full Bridge Converter using TPS7H5001-SP and TPS7H6003-SP

Jenson Seah
Prodigy 10 points
Part Number: TPS7H5001-SP
Other Parts Discussed in Thread: TPS7H6003-SP

Tool/software: Simplis

Hi, 

I'm designing a Full Bridge DCDC Converter with 24-38V input and 30V/20A output using TPS7H5001-SP and TPS7H6003-SP. I am referring to one of the schemas by TI to do out my design. However, I am facing issue understanding the highlighted part of the design. What is it for and how do i size it? Is it a voltage clamp? 

Additionally, this is my Design on Simplis. Why does the highlighted part experience a very high voltage of 150V and very high power losses through the resistors. Are you able to advise on the highlighted part of the design and if my circuit design is correct. Thank you!

  • +1
    TI__Mastermind 28615 points

    Hey Jenson,

    The part you highlighted in both SIMPLIS and the Schematic are diodes to help catch some of the current during the dead time.
    The R/C are to help dampen any parasitic ringing, so the sizing is dependent on your part choices and layout.
    Your SIMPLIS schematic may or may not be accurate in order to size these, since parasitics need to be taken into account.

    The parts highlighted in just the schematic are a simple RCD clamp in order to stop the parasitic spiking.
    Your SIMPLIS schematic may or may not be accurate in order to size these, since parasitics need to be taken into account.

    Thanks,
    Daniel

  • 0 in reply to Daniel Hartung
    Prodigy 10 points

    Hi Daniel, Thank you for replying.

    I see, so the sub circuit after the secondary GanFets is to catch some of the current during the dead time and deliver it back to the load?

    Additionally, can i check if it is normal for the secondary ganfets to experience such a high voltage of 160V? And do i need to clamp it down. Thank you!

  • +1 in reply to Jenson Seah
    TI__Mastermind 28615 points

    Hey Jenson,

    The diode with careful part selection will catch some of the current during the dead time.
    The R/C is used to damp ringing.

    What voltage they will get to is going to be based on your parasitics in your circuit.
    Your SIMPLIS simulation however is not a good indicator of what that voltage can get to.

    Thanks,
    Daniel

  • 0 in reply to Daniel Hartung
    Prodigy 10 points

    Hi Daniel, thank you for replying. I have a better understanding of the subcircuit now. Could I also check on how to size the diodes and R/C for that part of the circuit? Is there any data sheet or documents i can refer to

  • 0 in reply to Jenson Seah
    TI__Mastermind 28615 points

    Hey Jenson,

    The design you are referencing lists the BOM for reference.
    https://www.ti.com/tool/PMP23200

    Scroll looking for "Bill of Materials"

    Thanks,
    Daniel