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PCLK Swing Level of DS90UB925

Jeffrey
Expert 1920 points

Hi...

My customer is designing the DS90UB925/926.

There is a problem that the Lock of DS90UB926 is repeating a locking and unlocking.

I think that PCLK(74.25MHz) input waveform of DS90UB925 has a problem as follows.

But if PCLK of DS90UB913 EVM is applied on PCLK of customer board (DS90UB925), there is no problem.

PCLK of DS90UB913 EVM is as follows.

So I'd like to request the recommended solution. (for example. damping resistor or filter or etc)

I need your advice as soon as possible.

Thanks.

  • 0
    TI__Genius 14015 points
    Hello,

    It looks like that waveform of PCLK into the 925 is 6V, which is beyond the abs. max of the IO. There may be damage occurring.

    Can you confirm that this signal is actually 6V? If so, that would be the first thing to fix.

    Thanks,
    Jason
  • 0 in reply to Jason Blackman
    Expert 1920 points
    Hi Jason
    Thanks for your response.
    I think that the waveform of PCLK is weird, changed a probe so that normal waveform is observed.
    I tested the damping resistor (x ohm~xxx ohm) on PCLK line, but the problem is same even though swing level of PCLK is lower than before.
    I need the another solution like filter or bead or etc.
    I hope you recommend the best solution.
    Thanks.