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DS90UB901Q SerDes for Monochrome sensor

Pavel Shekhtmeyster
Prodigy 20 points
Other Parts Discussed in Thread: DS90UB901Q-Q1, DS90UB902Q-Q1

I was wondering whether the DS90UB901Q-Q1 supports input from a monochrome image sensor. The datasheet and the block diagrams indicate that the serializer is designed  to take in 14 bit YUV/RGB data. Intuitively, I don't imagine that monochrome data would be an issue, but I would like to have that confirmed.

Also, regarding the FPD Link III, since I am not that familiar with the protocol, the DS90UB901Q-Q1 data sheet states that it can reliably drive 688Mbps through 10 meters of 24 AWG twisted pair. What is the minimum gauge (smallest diameter) wire that I can drive that data rate, if I only need to go about 1m?

Thanks

  • 0
    TI__Genius 13475 points

    The DS90UB901 does not care if the data represents YUV, RGB or monochrome data, so in that respect, you are fine.

    The concern with cable length is AC attenuation.   If you are going to only be going 1m, vs 10m, you can afford 10x the attenuation per meter that you would get from the 24 AWG twisted pair.   Most cable manufacturers will specify their attenuation per meter at a few different frequencies, so you can easily compare - since the serial data rate is in the high 100s of Mbps, look for an attenuation number at a frequency in the ~1GHz frequency range for the comparison.   This should give you rough guidance as to which cables/lengths will work.

  • 0 in reply to Mark Sauerwald88474
    Prodigy 20 points

    Thanks for the info about the monochrome data Mark.

    Since our application is too compact for commercial cables, we'll be using a simple twisted pair of stranded copper, so I was wondering, according to the same metric that was used to find 24 AWG for 10 m at 688Mbps, what the minimum gauge of wire is required to go 1m at 688Mbps.

  • 0 in reply to Pavel Shekhtmeyster
    TI__Expert 3050 points

    Hi Pavel,

    We cannot provide a minimum wire gauge specification for the serial interconnect because the loss characteristics can vary greatly depending on how that cable is made. 

    However, looking at the datasheet's output VOD min value and input differential threshold values we can determine that the chipset can operate across an interconnect that has up to roughly 9.5 dB of loss. The DS90UB902Q-Q1 has an internal EQ which can be activated to help compensate for some amount of cable loss and increase your overall cable length.

    Aside from the wire gauge, it is important that any cable+ connector you choose be of a controlled differential impedance with relatively low loss across the operating frequency band of the link. 

    The 10m 24AWG typical cable reach noted in the datasheet was measured using a specific cable that is common to the automotive industry. This is discussed in the TRANSMISSION MEDIA section under APPLICATIONS INFORMATION in the  DS90UB901Q datasheet. 

    Mike Wolfe

    DPS APPS / SVA