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Original question:

UCC28951-Q1: UCC28951 PSFB DC-DC

UCC28951: UCC28951

Dr.J.Aran Glenn
Prodigy 80 points
Part Number: UCC28951

Tool/software:

Dear Sir,

We are using UCC28951 for designing PSFB Board for 4kW Charger. Can you give the procedure to do Fixed delay approach in UCC28951 for getting uniform DT. The dead time(DT) is Non-Uniform and there is a difference in Dead Time(DT1) and dead time (DT2) in all the high side switches A and C and low side switches B and D. The following results are the dead time between the switches

A and C VGS output DT1 500ns

A and C VGS output at DT2 1.7us

B and D  VGS output at DT1 680ns,

B and D VGS output  DT2  1.42us

Can you please advise how to change it as a Uniform Dead Time between all switches?. Thanks

  • 0
    TI__Guru* 85616 points

    Hello,

    Your inquiry is under review and I will get back to you shortly.

    Regards,

  • 0 in reply to Mike O'
    TI__Guru* 85616 points

    Hello,

    To design with a fixed delay approach you either tie ADEL and ADELEF to ground or use a voltage divider off of VREF to the ADEL and ADELEF pins.

    The following link will bring you to an application note that goes through the step by step design procedure of phase shifted full bridge using a fixed delay approach using the UCC28951.  

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

    Thank you for interest in Texas Instruments (TI) products.  If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

    Regards,