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DP83848I: how to replace from LXT972A to DP83848I/C/YB

Yasushi Fujiwara
Genius 12725 points
Part Number: DP83848I

Hello Experts,

My customer would like to replace from LXT972A to DP83848 and have a question as follows. Would you answer them?
1. Customer is using TXSLEW0/1 of LXT972A. Customer wants to know what function would be corresponding for by DP83848.
2. Customer wants to display an activity of LED, controlled by CFG_LED(0). He needs to display RX activity only. Can DP83848 this setting?
3. For MII Isolate mode, datasheet stated that DP83848 will be in MII isolate mode by strapping physical address 0. In case of start up of DP83848, customer should use other physical address, or it stay physical address 0 and then disabled MII isolate mode by register setting (BMCR register/bit 10), is my understanding correct?

Best Regards,
Fujiwara

  • 0
    TI__Mastermind 18425 points

    Hi Fujiwara,

    Is customer open to using DP83822? Its our newer device for 10/100Mbps ethernet. For DP83848 we have a rollover document http://www.ti.com/lit/an/snla092b/snla092b.pdf 

    1. We do not have slew rate control on DP83848. Do we know how customer plans to use it? We have slew rate control on our new 10/100 PHY DP83822.

    2. For DP83848, there is no option to display activity on RX only. This feature is also available on DP83822.

    3. Correct, MII isolate can be disabled through software.

    -Regards

    Aniruddha

  • 0 in reply to Aniruddha Khadye
    TI__Genius 12725 points

    Hi Aniruddha-san,

    For #1 question, customer is set slew rate by 3ns. There are spec of T2.8.1(p14 of datasheet) it is 4ns(typ). Is this for slew rate spec? Also the slew rate is specified by IEEE802.3 spec? I don't find such spec. Customer does not need to take care about it?

    DP83822 can replace from LXT742A? If so, do you have a rollover document like snla092b?

    Best Regards,
    Fujiwara

  • 0 in reply to Yasushi Fujiwara
    TI__Genius 12725 points

    Hi Aniruddha-san,

    Could you please provide your comments on this?

    Best Regards,
    Fujiwara

  • 0 in reply to Yasushi Fujiwara
    TI__Genius 12725 points

    Hi Aniruddha-san,

    Could you please provide your comments on this?

    > For #1 question, customer is set slew rate by 3ns. There are spec of T2.8.1(p14 of datasheet) it is 4ns(typ). Is this for slew rate spec? Also the slew rate is specified by IEEE802.3 spec? I don't find such spec. Customer does not need to take care about it?

    > DP83822 can replace from LXT742A? If so, do you have a rollover document like snla092b?


    Best Regards,
    Fujiwara

  • 0 in reply to Yasushi Fujiwara
    TI__Mastermind 18425 points

    HI Fujiwara-san,

    The PMD output pair follows IEEE standard and the customer does not need to take care about this. If the design requirement of the PHY is met, the PHY will output the correct waveform on the PMD pairs.

    DP83822 can work in applications where LXT972A is being used. However we do not have a roll over document for LXT972A  to DP83822.

    -Regards

    Aniruddha