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UCC28742: Switching frequency

Rohun Patel
Prodigy 10 points
Part Number: UCC28742

Hello, I'm wondering why the minimum switching frequency is 200Hz. I am trying to spec and select a transformer to use with this, but a switching frequency that low would saturate the core and reduce the primary winding inductance to 0. Can you provide an explanation for how to select a transformer that can accommodate this low frequency or some way to prevent the controller from switching that slowly? Thanks 

 

  • 0
    TI__Guru 73265 points
    Design transformer at full load switching frequency. Please review the datasheet application section where shows how to determine the turns ratio. Also you can download the excel design calculator from ti.com to help your design. Also WEBENCH can be used to help your design.

    At 200Hz, the transformer will be ok, since the peak current is limited as 1/4 of full load peak current. So the transformer will not be saturated.