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Original question:

UCC28950-Q1: UCC28950 PSFB switching frequency range

UCC28950-Q1: Changing operating frequency

Mohammed Khan
Intellectual 570 points
Part Number: UCC28950-Q1

Tool/software:

Hello mike,

I have a working prototype for vin : 600 to 975Vdc.

Operating frequency: 100Khz

Since I'm using Sic mosfets, I want to leverage their properties by increasing switching frequency to let's say 200khz. Should I change any delay resistors or just change value of RT and start. 

Is there any impact on loop resospone??

Is there something specific I need to take care ???

  • 0
    TI__Guru* 86176 points

    Hello,

     

    If you are only changing the switching frequency you should not have to change your delays.

    In regards to loop compensation if you have not changed your output L and C your double pole frequency will stay the same and your compensation should remain unchanged.

     

    If you are designing for a higher switching frequency you should take advantage of designing new magnetics for a higher switching frequency.  This will give you smaller magnetics.  If you do this then it is advisable to do the following.

    1. You will have to change the delays to achieve valley switching. This is because the inductances in circuit have changed and the LC ring period will change.
    2. If you use a smaller output L the double pole frequency in the control to output transfer function will change. This will allow you to design for a higher crossover frequency.

    Regards,