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UCC28950: Inquiry Regarding Tmin Setting for UCC28950

철하 강
Prodigy 20 points
Part Number: UCC28950

Tool/software:

Hi,

I am currently implementing and testing a PSFB converter using the UCC28950 chip.

I have a question about the Tmin setting. The datasheet states that Tmin should be set to the minimum duty cycle that allows for ZVS (Zero Voltage Switching) under light-load conditions, but I need a more detailed explanation of this.

Could you please provide any design guidelines on this topic? Also, if you have any reference documents I could review, I would greatly appreciate it.

  • 0
    TI__Guru* 85806 points

    Hello,

     

    Tmin setting determines when the device goes into burst mode.  Burst mode is triggered when the duty cycle/(switching frequency is less) < Tmin. 

     

    In regards to ZVS you need to properly select the shim inductor (Ls) and set the delay timing of the device.  The following will bring you to and application note that discusses how to select Ls and setup the delay timings to achieve ZVS.

    https://www.ti.com/lit/pdf/slua560

    Regards,