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DS125DF410: signal detect

K.Shidara
Expert 3225 points
Part Number: DS125DF410

Hi Team,

I have a question on Retimer IC DS125DF410 Signal Detect,

I would like to set Signal Detect to be turned on when a certain level or more of signal is input. Is the register that can change the signal level the following address?

Channel Register 0x14 bits4, 5

It seems that you can change to 4 levels with this 2-bit register,
How much will the input level be asserted for the following four combinations?

   bit5 bit4
     0 0 ← Is it 0V?
     0 1
     1 0
     1 1

Also, do you think that the signal detect circuit does not start up if input of bit 2 and 3 of the same register is below a certain level?

  • 0
    TI__Guru* 93670 points
    Hi Shidara-San,
    Reg 0x14[5:4] set the signal level at which we would declare or assert signal detect. Any signal level at or above this level we declare signal detect. Default value - reg 0x14[5:4]='b00 is 70mV.
    Reg 0x14[[3:2] set the signal level at which we declare there is no signal. Default value - reg 0x14[3:2]='b00 is 10mV. Any signal level at or below this value we declare there is no signal.

    Signal level between these values - i mean between 10mV and 70mV - is non deterministic. We may declare signal detect or we may not declare signal detect. But if signal detect is declared it stays asserted.

    However, i don't know signal detect levels for other settings and i am looking into finding these values and will let you know.

    Regards,,nasser
  • 0 in reply to Nasser Mohammadi
    TI__Expert 3225 points
    Hi Nasser-san

    Thank you very much for your quick reply.
    Does non-deterministic mean another combination setting should be used for just keeping detect judgement
    in other words, detect function can work with only "00" setting even if the different level found?

    If you find below matrix detect level, would you let me know.

    addr 0x14 bit [5:4]
    SDH Signal Detect ON Threshold Level
    00 70mVpp
    01 ?
    10 ?
    11 ?

    addr 0x14 bit [3:2]
    SDH Signal Detect OFF Threshold Level
    00 10mVpp
    01 ?
    10 ?
    11 ?

    Thanks
    Best regards,
    Shidara
  • 0 in reply to K.Shidara
    TI__Guru* 93670 points
    Hi Shidara-San,

    Non-deterministic means we are in hysteresis area.

    Here is the typical value that we expect:
    SDH Signal Detect ON Threshold Level
    00 70mVpp
    01 61mVpp
    10 80mVpp
    11 75mVpp

    addr 0x14 bit [3:2]
    SDH Signal Detect OFF Threshold Level
    00 10mVpp
    01 7mVpp
    10 15mVpp
    11 12mVpp

    Regards,,nasser