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UCC24624: Using the UCC24624D synchronous rectifier controller on the output of a phase shifted full bridge converter with a variable output voltage

Stephen Oberholzer
Prodigy 65 points
Part Number: UCC24624
Other Parts Discussed in Thread: UCC28951, UCC2895, CSD19536KCS,

Good morning,

I am designing a 1.5kW phase shift bridge converter with a variable output voltage between 5V and 45V.

My intention is to use the UCC2895 for this. (Note: I do not want to use the UCC28951 in this application)

Power output reduces as the output voltage reduces.

Maximum power is only possible at 45V output.

I would like to use the UCC24624D for controlling your CSD19536KCS MOS FETs on the output as synchronous rectifiers.

The variable voltage is a problem for powering the UCC24624D. 

I could provide a separate fixed regulated voltage feeding the UCC24624. What is your opinion on this?

Otherwise I could use a pulse transformer circuit driving the synchronous rectifiers from the signals on the primary side.

My only concern is when the converter enters DCM.

Can the synchronous FETs really be damaged when using the pulse transformer circuit in SLUU109B?

Thank you.

  • +1
    TI__Genius 9140 points

    Hi Stephen,

    please keep in mind UCC24624 can be worked normally with VCC from output voltage.

    if customer use external VCC for UCC24624, please make sure the supply of UCC24624 should be slower than output voltage rise up.

    you can find it from the datasheet about the item I mentioned.

    and my understanding is that there is no relationship of SR mosfet demage and pulse. I do not think SR can be demaged when pulse transformer is used.

    hope this helps you.