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UCC28056: Minimum switching frequency can be reconfigured?

Pei Han Ng
Prodigy 30 points
Part Number: UCC28056

I am just wondering if it is possible to change the minimum switching frequency? Or by default the minimum fsw will be defined by the Tonmax0?

I understand that by changing the feedforward voltage, you will be able to get to different G level, but then how do I modify the COMP pin voltage? From what I see in the datasheet, COMP voltage seems to only have compensation loop?

Thanks

  • 0
    TI__Expert 3095 points
    Hi Pei Han Ng,
    Thank you for your interest in this TI part.
    How do you wish to change the minimum switching frequency. Do you wish to increase it or reduce it?
    Thanks
    Joe Leisten
  • 0 in reply to Joe Leisten
    Prodigy 30 points

    I would like to increase it.

    I understand that there is this Ton max. How should I modify in order to use another Ton max as the starting point? Or it is internally decided?

    Pei

  • 0 in reply to Pei Han Ng
    TI__Expert 3095 points
    Hi Pei Han Ng,
    For this part, with only six pins, the minimum switching frequency cannot be adjusted externally. The switching frequency is a function of the COMP Pin voltage level and the input voltage peak (sensed via the ZCD/CS pin) only. To limit the minimum frequency you must either limit the minimum COMP Pin voltage (this will also disable burst operation) or you must limit the sensed peak input voltage. Both of these methods have significant consequences for power delivery control and are not recommended.
    If you can share any information regarding your target application and minimum frequency requirement this will help us in proposing future devices.
    Thanks
    Joe Leisten