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DS90UB953-Q1: Horizontal Line Limitations

Jared Becker
Genius 11845 points
Part Number: DS90UB953-Q1
Other Parts Discussed in Thread: DS90UB954-Q1, DS90UB941AS-Q1

Hi Team,

Are there are horizontal line limitations for any FPD3 serializers or deserializers? For example, if I wanted to use a 953 with Hpix = 8000, Vpix = 1000 and frame rate is 10, will any of the FPD3 ADAS SERDES have an issue transmitting this?

Thank you,

Jared

  • 0
    TI__Guru** 103215 points

    Hello Jared,

    For 953 there isn't any limitation because the 953 does not buffer an entire video line before sending. The limitation would come on the deserializer side because the deserializer does buffer a full video line before transmitting out the CSI-2 interface. Also you need to know the number of bits per pixel. 

    As an example, let's say your video format is RAW12 for the above, so 8000pix * 12 bits = 96000 bit per line / 8 bits = 12kb per line. DS90UB954-Q1 for example has a 16kb line buffer (FIFO) per port, so it could support support this format, so long as the average rate of video lines coming in is slow enough to ensure that the line buffer won't overfill on the DES which also depends on the configured CSI-2 output rate (which would determine the FIFO drain rate) and the CSI-2 lane rate/line timing on the CSI-2 input side (which would determine the FIFO fill rate).

    Best Regards,

    Casey 

  • 0 in reply to Casey McCrea
    TI__Genius 11845 points

    Hi Casey,

    Thank you for the insight! To clarify, all FPD3 serializers do not have a limitation, correct?

    In the math above, why did you divide the 96000 bit per line by 8 bits?

    Thanks,

    Jared

  • +1 in reply to Jared Becker
    TI__Guru** 103215 points

    Hello Jared,

    All FPD ADAS CSI-2 serializers work like this, but not all FPD3 serializers in general. For example DS90UB941AS-Q1 for example has a line buffer, so it does have similar line length limitations. 

    Sorry for the above I should have been more clear about bytes vs. bits. The 954 line buffer has 16kilobytes size, so dividing by 8 was converting bits to bytes. 

    Best Regards,

    Casey