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DS90CR286A question

Other Parts Discussed in Thread: DS90CR286A

Hello,

My customer uses the DS90CR286A.

He has some questions about the figure 11 on the datasheet.

Q1) Are the RxIN0-RxIN3 expressed differential signal?

Q2) Is the intersection with a signal and a dotted line at 50% level?

Q3) I ask a basic question. What it means "strobe position" ?

Regards,

Naoki Aoyama

  • Hi Naoki,

    I think Figure 13 will give you a clearer picture on Rpos(n).

    Strobe position refer to the time placement when the internal strobe clock is used to sample the incoming data bit streams.

    regards,

    TK Chin

  • Hi Naoki-san,

    Regarding Figure 11:

    1.  Yes. The RxCLK IN is expressed as a differential (RxCLK+) - (RxCLK-) signal, so we can expect that RxIN0 are also expressed as differential signals.

    2. The intersection of the dotted line and the signal may not necessarily be the 50% rising/falling level. That level may depend on the rising/falling edge rate of the signal. It is more important to focus on the min/max time for each strobe position in accordance with the "Receiver Switching Characteristics" table on p. 3.

    3. Strobe position is the location in time when a certain bit is read by the receiver. The min-max strobe position indicates the window of time in which the signal level for that bit is valid and not in the midst of a transition or invalid state.

    Thanks,

    Michael

  • Hi TK Chin,

    Thank you for your reply and I understand the Figure 13.

    Thanks

    Naoki

  • Hi Michael,

    Thank you for your reply. I understand the Figure 11 and strobe position.

    My customer has another question about table on P.3.

    He uses the device with 54MHz clock. 

    How about the switching characteristics? 

    Regards,

    Naoki

  • Hi Naoki-san,

    We do not have production/test data for 54 MHz clock available, so I can only provide an estimate of typical values based on calculation with fCLK = 54 MHz and assuming the strobe position occurs approximately at the midpoint of each bit's duration:

    Symbol Parameter Typ Units
    RsPos0 f = 54 MHz 1.3 ns
    RsPos1 4.0 ns
    RsPos2 6.6 ns
    RsPos3 9.3 ns
    RsPos4 11.9 ns
    RsPos5 14.6 ns
    RsPos6 17.2 ns

    Michael

  • Hi Michael,

    Thank you for your reply.

    I will feedback to my customer your information.

    Thanks

    Naoki