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DS90UB954-Q1: DS90UB954-Q1 and DS90UB953-Q1 connected in FPD link and loosing frames.

Tzachi Bear97
Intellectual 320 points
Part Number: DS90UB954-Q1

hi 

in my system i am connecting two boards with a FPD link III

in one board i have my camera and sensors, and the ds90ub953 as a serializer,

and in the other i have the ds90ub954 that is my de-serializer,

for some reason i am having lost frames, not always, but it happens

another observation is that when ever i turn the lighting on (even external) i am losing frames as well

as for error indication - i can see errors only in the ds90ub954, the ds90ub953 registers are all clean,

any ideas what this could be? what should i check?

is there a way to control the drive of the signal that comes out of the ds90ub953? does it has any kind of pre-emphasis and de-emphasis of the signal?

also the serial capacitors between the two components - what should be their voltage rating?
i dont have PoC, can i use a lower voltage than the 50v in the EVM?

thanks

  • 0
    TI__Mastermind 30515 points

    Bear, pls check below comments:

    1. From the error detection and unlock issue in your UB954 board, we can get that the link design between ub953 and ub954 is not good. UB954 has optimized AEQ which can compensate >15dB  channel loss, pls make sure that the channel s12/s11 is following up the s11/s12 request in d/s. From your test result, it seems the link jitter margin is not enough it is NOT channel compensation issue. but anyway pls review the link design performance such as channel parameter, supply noise, ref.clk noise, etc.

    2. regarding the rating voltage 50V recommendation from AC coupling, since this ac coupling cap. is put close to the connector with cable, it is easily impacted by external surge, so we recommend the rating voltage to be 50V. But if your application condition is well, you can relax this spec.

    best regards,

    Steven