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TPS51362: Jitter Issue

Patrick Chen
Mastermind 8875 points
Part Number: TPS51362

Hello,

               For VCCIO, customer use TPS51362 and find jitter a little large issue on measurement. Do you have any comments for it? Thank you.

BR

Patrick

  • 0
    TI__Expert 5745 points

    Try to disconnect the PR80 and PR83. If the jitter decrease, it's may be some noise go into the VSNS pin. So add a small cap(0.1uF) near the VSNS pin to filter the noise.

  • 0 in reply to Vental Mao
    Mastermind 8875 points
    Hello Vental.

    Customer removed the PR80 and PR83 and add a small cap(0.1uF) near the VSNS pin, but the phenomenon not improve. So what reason cause it?? Thanks.

    BR
    Patrick
  • 0 in reply to Patrick Chen
    TI__Expert 5745 points
    Normally , the main reason of the large jitter is because the slew rate of the (CSP - CSN) or (CSP - CSN) is too small or small noise couple to these signal. you can see the figure 20 in the datasheet.
    So i suggest to remove the PR80 and PR83 before to avoid the noise couple to the (CSP-CSN) to make a false trigger. But it seems useless.
    1, Please see the waveform of the VSNS, VREF, VSLEW (AC couple)to make sure them don't couple lots of noise(increase the cap a little if there is some noise) .
    2, See the ripple of the Vout, make sure the ripple is <15mV to avoid the big output ripple affect the Ton trigger.
    3, By the way , Is this issue only happened in the heavy load?
  • 0 in reply to Vental Mao
    TI__Mastermind 18510 points

    Add more comments here.

    1, How much of the jitter? zoom in for only one pulse to check it. and what's the loading for the testing? 

    2, if you use remote sensing, PR74/213 should be dummy. and routing Gsens/Vsense differential line,away from noise source. and keep Vref away from noise as well. you can check Vsense/Vref whether there is noise coupling as Vental mentioned.

    Regards,

    Yuchang