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DS90UB954-Q1: Hardware design question

Zongtao Wang
Prodigy 140 points
Part Number: DS90UB954-Q1

hello expert:

1.about the AC coupling capacitor 

is it necessary to keep the same value of capacitors both at 954 and 953?

2.there is amplitude requirement about the REFCLK ,actually at my design ,i used the crystal as REFCLK input ,but the sine waveform have 300mv bias ,the 954 can not works normally ,and decrease the bias ,the 954 can works normally ,i want to if there any requirement about the REFCLK low voltage and high voltage ?

  • 0
    TI__Mastermind 28020 points

    Hello,

    1. AC coupling capacitors should be the same on both the SER and DES side. On the DOUT+/RIN+ sides, the two capacitors in series will have a total capacitance of 33nF/2 = ~16.5nF. On the DOUT-/RIN- sides, there is 15nF capacitance. The effective capacitance should be balanced on the + and - FPD-Link transmission line.
    2.  For the 954 REFCLK, VIH/VIL follows 1.8V logic (as defined in the DC Electrical Characteristics table in the datasheet). VIH(min) is defined as 1.15V. You need to meet the datasheet specs for consistent performance across all 954 units.

    Best,

    Justin Phan