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DP83822IF: Signal Detect Questions

Kazuki Itoh
Genius 10770 points
Part Number: DP83822IF

Hi team,

My customer is trying to connect media-side to 100BASE-FX and use LED_1/GPIO1 as signal detect.

Could you please help me answer my customer's questions  below?

1. Is the input signal supposed to follow Table 7.5 VDDIO VIH/VIL level? My customer wants to double check it because other vendors defines that it Signal Detect follows LVPECL.

2. DS p.40 8.4.4.2 recommends to use Signal Detect when 100BASE-FX. What is the disadvantage of not using Signal Detect here?

3. About the statement below:

if the electrical link between the fiber module and the DP83822 is broken, disconnected or otherwise disrupted, the link will recover only by initiating a soft reset through MDIO/MDC interface.

Does the Signal Detect continue to detect under the condition that the optical fiber is disconnected? My customer cares about that because it may need soft reset.  

Regards,

Itoh

  • 0
    TI__Genius 9920 points

    Hi Itoh,

    1. Hi Itoh, yes since it is a IO pin it can follow VDDIO. 

    2. The disadvantage would be that you would not be able to use LED_1 as an indicator or as GPIO if you would prefer to use it as Signal Detect instead. 

    3. According to the statement, if there is a disconnection while both partners are on, you will need to recover the link by doing a soft reset. 

    Thanks,

    Cecilia