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TPS563257: Jitter reduction by external component

Roy Hsu
Intellectual 2880 points
Part Number: TPS563257

Tool/software:

Hi Team,

May I know what's item will affect the jitter cxcept for layout? 

And I think BW will affect jitter since faster response then the frequency range will within a lower range compared with slower response time correct?

Best Regards,

Roy  

  • 0
    TI__Genius 17450 points

    Hi Roy,

    I think your "jitter" means the frequency/period random changing. Usually it's caused by noise on FB node, so if you add a capacitor on FB node, decrease crossover frequency at the same time, the jitter will be small.

    Thanks,

    Shipeng

  • 0 in reply to Shipeng Cheng
    TI__Intellectual 2880 points

    Hi Shipeng,

    Yes, the "jitter" I mean the off time jitter (I think it same as you mention), so may I understand as lower BW will reduce jitter? Any why? Because I will think if BW higher, response speed higher may lead to the switching frequency range smaller like if I setting 600k, it will from 597k~603kHz, and if lower BW it will become maybe 595k ~ 605kHz  

    Conclusion my questions as below.

    1. Why reduce BW will reduce jitter?

    2. Do we have some calculator for feedforward capacitor?

    3. Do we have any jitter spec?

    Best Regards,

    Roy

  • 0 in reply to Roy Hsu
    TI__Genius 17450 points

    Hi Roy,

    For Cff you can refer to datasheet recommendation value. There's no jitter spec for DCAP device.