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[FAQ] DS125DF1610: How to setup DS125DF1610 cross point registers?

Part Number: DS125DF1610

You have different trace lengths on inputs of the DS125DF1610 device. How do you set up cross point registers to allow every channel CTLE to adapt to it's incoming signal loss characteristics?

  • First - before we start our discussions - please make sure you have reviewed DS125DF1610 Programmig guide.

    DS125DF1610 is a 16-channels retimer. Additionally there are quad 4 X 4 cross point. Since each channel input may have a different loss characteristics, care should be taken to setup channel and CTLE control for each channel. Let’s take a close look at input channel register settings.

    Reg 0x96[1:0] : These two bits define where the high speed data for this channel is coming from.

    Reg 0x9B[1:0]: These two bits define which channel CTLE is being used for this channel.

    To make this clear, let’s look at a couple of examples.

    In first example, we are connecting input 4A to output 4B, input 4B to output 4B, input 5A to output 5B, and input 5B to out 5A.

    Input Channel#

    Output Channel#

    Data source for input channel 0x96[1:0]

    CTLE control for Input Channel 0x9B[1:0]

    4A

    4B

    01

    Don’t care 4A not used

    4B

    4B

    01

    01

    5A

    5B

    11

    11

    5B

    5A

    10

    10

    Note 2: 0x96[1:0] and 0x9B[1:0] refer to input channel register settings

    In second example, we are connecting input 4A to output 4B, input 4B to output 4B, input 5A to output 5B, and input 5B to out 5A.

    Input Channel#

    Output Channel#

    Data source for input channel 0x96[1:0]

    CTLE control for Input Channel 0x9B[1:0]

    4A

    4B

    01

    Don’t care 4A not used

    4B

    4B

    01

    01

    5A

    4B

    01

    11

    5B

    5A

    10

    Don’t care. 5B not used

     Regards,,,nasser