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UCC28610 switching frequency

Carlos Mojarro2
Prodigy 30 points
Other Parts Discussed in Thread: UCC28610

Is there a way to keep a fixed switching frequency on UCC28610 regardless of the load?

Or at least keep it above 60KHz. The switching freq on AM mode is causing noise on my device.

Any help is appreciatted.

  • 0
    TI__Mastermind 31580 points
    Hi Carlos,

    I will get one of the engineers to contact you. In general audible noise should only be apparent below 20kHz and the usual source is the transformer. Ensuring the core and bobbin are glued together to prevent the core vibrating usually helps or ideally vacum impregnation of the transformer.

    Regards

    Peter
  • 0 in reply to Peter Meaney
    Prodigy 30 points

    Hi Peter,

    The application is not audio. I'm powering a sensor that is affected by switching frequencies below 60KHz.

    I'm trying to stay away from those frequencies without having to change the controller.

  • 0 in reply to Carlos Mojarro2
    TI__Genius 15910 points

    The UCC28610 can be configured for constant switching frequency by connecting a resistor from FB to VDD for a fixed FB current.  Control has to be done by using the MOT pin.  The MOT has to be used to modulate the on-time by connecting it to the opto-coupler, instead of connecting the FB pin to the opto.  A resistor is connected to MOT to ground for the maximum on time, then the collector of the opto is connected to MOT with a series resistor for constant on-time control, essentially varying the MOT total resistance.