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DP83822IF: Some questions about PHY like DP83822

Sulyn ZHANG
Expert 8700 points

Part Number: DP83822IF

Hi Expert,

I have several questions about PHY, can you do me a favor to check, thanks:

1. Take DP83822 as example, we have the PMD output specific for 100BASE-TX as below, so do we also have the specific for receiver input? Is it same with Output specific?

2. For the eye waveform we showed in our datasheet. Not sure what's the test condition for this eye waveform, for example we test this waveform when connected to transform and RJ45 connector? If not, pls correct me, thanks.

3. Do you have some documents to show the MLT-3 electronic specifics and related waveform for PMD output and input?

Thanks a lot for your support!

Best regards,

Sulyn Zhang

  • 0
    TI__Mastermind 18425 points
    Hi Sulyn,

    The PMD output spec is defined in the IEEE standards and the device is tested to make sure that it is compliant to IEEE standard. The standard however does not define the receiver input requirement for the PHY, so it is not possible to test that.

    For generating the eye diagram, the PHY is configured to transmit MLT-3 scrambled idles by writing 0x2100 to register 0x00. The output of the PHY is connected to 100ohm differential termination resistors via RJ-45 connector and Cat5 cable. The differential probe is then used to measure the signal across the 100ohm differential termination resistor.

    The IEEE standards and ANSI FDDi TP-PMD standards will contain information about 100Base-TX transmitter and receiver. The standard documents are copyright protected materials, so we would not be able to distribute them to customers. Customer would have to purchase their own copy.

    -Regards,
    Aniruddha