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DS90UB953A-Q1: backwards compatibility of the 953/954 serdes modules

Viktorija Cecil
Mastermind 18511 points

Part Number: DS90UB953A-Q1

Team, my customer has a question regarding the backwards compatibility of the 953/954 serdes modules:

It appears they are only compatible with 913/914 and 933/934 with the proper circuit as outlined in http://www.ti.com.cn/cn/lit/an/snla270a/snla270a.pdf. Notably the AC capacitors need to be changed and external clock added to 953 for DVP mode.

Is there any way to make the circuit compatible with both 953 and 913/933, and the mode can be configured purely through the register settings?

We designed a board for the 953/954 and later realized it doesn't work with a 913 serializer unless we swap out those capacitors. We would like to have it compatible with all using the same hardware.

Thanks!

Viktorija

  • 0
    TI__Guru** 103215 points
    Hello Viktorija,

    The AC coupling caps used for 913A are compatible with 953 operation as well (100nF, 47nF). So you can use those for both implementations and then configure the 954 registers for MODE strapping override based on which serializer you are using.

    Please ensure that you are using 913A, not 913 because 913 (non-A version) does not support coax.

    Best Regards,
    Casey
  • 0 in reply to Casey McCrea
    TI__Mastermind 18511 points

    Casey,

    Thanks for quick reply. Just to confirm...

    A 954 deserializer with  (100nF, 47nF) caps should be able to link to:

    1. 913A serializer with (100nF, 47nF) caps

    2. 953 serializer with (100nF, 47nF) caps

    2. 953 serializer with (33nF, 15nF) caps  

    Is this correct? I just found this table in the docs which seems to verify this.

    Then we can just use (100nF, 47nF) caps for all out 953/954 design and it should like to any other 91X, 93X, 95X.

    Thanks

    Viktorija

  • 0 in reply to Viktorija Cecil
    TI__Guru** 103215 points
    Hello,

    Ideally for the 953 case the caps should also be 100nF, 47nF but I think it should be ok in this case as well. All others are fine

    Best Regards,
    Casey