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DP83867CS:Regarding the phase noise mask specification for the Clock In (XI) pin

user6236094
Intellectual 310 points
Part Number: DP83867CS
Other Parts Discussed in Thread: DP83869HM, , DP83867E

HELLO

Please tell me about the phase noise mask specification for the Clock In (XI) pin.

【Question1】
　　Please tell me about the following 25-MHz Oscillator Specifications.
　　The following phase noise mask specifications are in the DP83867CS but not in the DP83869HM.
　　Why is it only in the DP83867CS?

【Question2】
　　　I have selected a crystal oscillator, but I cannot find a part that meets the following specifications.
　　　Are the following specifications always required?
　　　Also, what kind of impact will occur if the following requirements cannot be met?

　　◇25-MHz Oscillator Phase Noise
　　　・10Hz　 ：-90[dBc/Hz](MAX)
　　　・100Hz　：-90[dBc/Hz](MAX)
　　　・1KHz　 ：-100[dBc/Hz](MAX)
　　　・10kHz ：-125[dBc/Hz](MAX)
　　　・100kHz ：-125[dBc/Hz](MAX)
　　　・1MHz　 ：-125[dBc/Hz](MAX)

  • 0
    TI__Mastermind 25955 points

    Hi,

    I would like to have a clarification are you using Oscillator or Crystal? The spec you send me only apply to Oscillator.

    If you are using Oscillator, could you send me the spec of the oscillator that you want to use. We can double check on our side rather it is good for DP83867.

    --

    Regards,

    Hillman Lin

  • 0 in reply to Hillman Lin
    Intellectual 310 points

    Hi,

    I will answer below.
    Is it possible to use the following crystal oscillator (25MHz) with the DP86837?
    (1)SIT8008BC-12-18S-25
    (2)510KCA25M0000CAGR

    1.SIT8008BC-12-18S-25 phase noise mask specification
    ・10Hz : Not listed
    · 100Hz: -80 [dBc/Hz] (MAX)　:　 FAIL?
    ・1KHz : -129[dBc/Hz](MAX)
    ・10kHz: -135dBc/Hz] (MAX)
    ・100kHz: -135[dBc/Hz](MAX)
    ・ 1MHz: -145 [dBc/Hz] (MAX)

    2.510KCA25M0000CAGR phase noise mask specification
    ・10Hz: -77.2121 [dBc/Hz] (MAX)　:　 FAIL?
    ・100Hz : -107.0260[dBc/Hz](MAX)
    ・1KHz : -128.5569[dBc/Hz](MAX)
    ・10kHz: -134.1216[dBc/Hz](MAX)
    ・100kHz: -139.9906 [dBc/Hz] (MAX)
    ・ 1MHz: -148.5667 [dBc/Hz] (MAX)

  • 0 in reply to user6236094
    TI__Mastermind 25955 points

    Hi,

    We double check on your spec for the oscillators. Both of them should be good for DP83867.

    --

    Regards,

    Hillman Lin

  • 0 in reply to Hillman Lin
    Intellectual 310 points

    Hi,

    Regarding the check of the above two crystal oscillators, I would appreciate your favor.
    I also investigated the crystal oscillator mounted on your DP83867 evaluation board.
    Here, "SG-210STF 25.000000 MHz S" was implemented.
    I think the phase noise specs at 10Hz and 100Hz also meet the regulations.
    At present, the above two product names cannot be used, and I believe that the only option is to use this crystal oscillator.

    ◇SG-210STF 25.000000 MHz S　PHASE NOISE

    ◇DP83867 evaluation board（DP83867E SGMII EVM(snlu209)）

  • 0 in reply to user6236094
    TI__Mastermind 25955 points

    Hi,

    We would recommend using SG-210STF 25.000000 MHz S if possible. However, out of the two oscillator you recommend, 2.510KCA25M0000CAGR would be a better choice.

    --

    Regards,

    Hillman Lin