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DP83869HM: Signal detect logic

viktor zalud
Prodigy 140 points
Part Number: DP83869HM

Tool/software:

Hi,

I have question to the Signal detect signal. in datasheet there is written some information abut SD signal, see below. Basically I understand that it is Signal detect  this (active high), but on other picture is mixed signal lost / signal detect in one picture. This means that PHY has possibilities to set via registers the logic? In default state its behave as SD but in registers is possible to set it to LOS? what is the name of register.

  • 0
    TI__Mastermind 39855 points

    Hello,

    Signal detect and Loss of Signal are just two different names to describe the same functionality. Once the transceiver detects appropriate communication, this will relay to the PHY accordingly (typically). If you are concerned about polarity detection of this pin, you may look to reconfigure using Reg 0xC30[2]. Please note this is an extended register.

    Sincerely,

    Gerome

  • 0 in reply to Gerome Cacho
    Prodigy 140 points

    Hello,

    I think that writing that SD and LOS signals are two different names for the same function is not really. SD signal si mainly used for 100Base-FX transceivers but there is not specification of levles. some Vendor has 3V3 CMOS logic, come have LVPECL. in case of 1000BASE-X transceiver, thez have only LOS define by standard. Anyhow, the voltage levels are inverted and you can see form previous sentence that even voltage levels are not possible. This must be taken to the count. But since you write that the SD signal act in DP83869HD it means that is low active.  

    I wanted to see description of the extended register 0xC30 but I did not really understand where I can found the description. Can you name page where it is possible to see this register? We need to set function of SD pin at DP83869HM to the LOS (high active)

  • 0 in reply to viktor zalud
    TI__Mastermind 39855 points

    Hello,

    This register description is not available in the datasheet. We will look to take a note for future revision. 

    Please look to toggle 0xC30[2] to switch configuration between active high and low. It is our understanding that default is active high.

    Sincerely,

    Gerome