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DP83848T: ESD characteristics and related questions about DP83822I/DP83825I

Part Number: DP83848T
Other Parts Discussed in Thread: DP83825I, DP83822I, , DP83822IF

Hi team

 

I have questions about DP83848T/DP83822I/DP83825I.

 

  1. In DP83848T datasheet, ESD ratings are below.
    HBM +/-4kV
    CDM +/-1kV
    I understand that no ESD protection diodes in DP83848T. The above ESD spec is applied to all pins including MDI pins or only pins except MDI?
  2. DP82825’s ESD rating are below.
    HBM +/-5kV(MDI)
    HBM +/-2kV(except MDI)
    ESD protection diodes are added in DP83825I for MDI, although no ESD protection in DP83848T?
    Pin’s ESD ratings except MDI of DP83825I get weaker than DP83848T? I mean, all pins of DP83848T are +/-4kV@HBM, but pins except MDI of DP82825I are +/-2kV@HBM.


    Below are questions about DP83825I
  3. What is voltage mode line driver?
    DP83848T also has this function? What are improved in DP83825I
  4. Are there any registers in DP83822I to set Class A or Class B, though DP82822I has?
  5. Could you share any information of Integrated MDI and MAC Termination Resistors? No information in the datasheet.


    Below are questions about DP83822I
  6. 10.1 Power Supply Characteristics are the case of class A?
    Are there any data in the case of class B?
  7. When should we adjust line driver swing by setting Line Driver Control Register (LDCTRL)?

    Below are questions about DP83822IF
  8. In 100BASE-FX, LVPECL is required for SFF/SFP communication. But it seems no description in the datasheet.
    This will be added later?

 

 

  • Hi,

    In general, ESD ratings ( HBM, CDM) are important on the pins which are exposed to Electro Static . For example MDI pins are terminated to RJ-45 connector and exposed to external Elector static discharge.

    1. I understand that no ESD protection diodes in DP83848T. The above ESD spec is applied to all pins including MDI pins or only pins except MDI?
    This is not correct. ESD protection is specified in datasheet. It's shall be applicable to all pins as no exclusion is specified.

    2. ESD protection diodes are added in DP83825I for MDI, although no ESD protection in DP83848T?

    This is not correct. Both have ESD protection as specified in datasheet.


    3. What is voltage mode line driver?
    DP83848T also has this function? What are improved in DP83825I

    Voltage Line Driver enables integration of external terminations on MDI side internal to device. DP83825 power consumption is also improved for AVDD 3V3

    4. Are there any registers in DP83822I to set Class A or Class B, though DP82822I has?

    What is Class A and Class B registers ??

    5. any information of Integrated MDI and MAC Termination Resistors?

    Please refer to DP83825 EVM schematics. It does not need external termination on both MDI and MAC side.

    6. Power Supply Characteristics are the case of class A?

    What is class A ??

    7. When should we adjust line driver swing by setting Line Driver Control Register (LDCTRL)?

    It shall not be needed as DP83848/822 complies to IEEE Transmitter spec. It may be for some specific use-case but not needed for regular use-cases.

    8. In 100BASE-FX, LVPECL is required for SFF/SFP communication.

    Connections for Fiber interface are shown in the Application sections. Recomendation is have series capacitor and let SFP adjust the DC levels.
  • Geet,

    Thanks.

    a. Comparing ESD ratings between DP83848T and DP83825I like below, DP83825I pins except MDI are weaker than DP83848T in terms of HBM?

    DP83848T: HBM +/-4kV

    DP83825I: HBM ±5KV (MDI)

                 HBM ±2KV (except MDI)

    4. Are there any registers in DP83825I to set Class A or Class B, though DP82822I has?

    What is Class A and Class B registers ??

    Please see P.75, table 75 of DP83822 datasheet. No registers same with this in DP83825.

      5. any information of Integrated MDI and MAC Termination Resistors?

    Please refer to DP83825 EVM schematics. It does not need external termination on both MDI and MAC side.

    They would like to know more specific information, kinds of resisters and the resister accuracy of MDI and MAC termination.

    Could you give more information, so that they can consider to draw the schematic?

    6. Power Supply Characteristics are the case of class A?

    What is class A ??

    Same with above. Could you provide anything? They guess that the supply current for AVDD and magnetic supply would be increased.

     

    Regards,

    Noriyuki Takahashi

  • Geet,

    This is a kind reminder.
    Could you give any comments?

    Regards,
    Noriyuki Takahashi
  • Hi Noriyuki-san,

    Sorry for late response.

    . Are there any registers in DP83825I to set Class A or Class B, though DP82822I has?

    What is Class A and Class B registers ??

    1. Why these are needed ? We are not looking to offer Class A or B options on Dp83825. On DP83822, it was offered to support capacitivite coupling. DP83825 by default supports both magnetics and capacitive coupling.


    They would like to know more specific information, kinds of resisters and the resister accuracy of MDI and MAC termination.

    2. MDI output is compliant to IEEE, hence we don't need to share the terminations resistor details. On MAC side, we provide register configuration to tune the resistance.




    3. Same with above. Could you provide anything? They guess that the supply current for AVDD and magnetic supply would be increased.

    Given it's voltage line driver, it does not consme power from Magnetics supply. We are not looking to offer Class A or B on DP83825, hence Power consumption shall remain same.
  • Geet,

    Sorry for confusing.
    Please let me ask again.

    1. Could you share more specific information of Integrated MDI and MAC Termination Resistors integrated in DP83825I?
    I guess that the specific resistor values with errors are determined. But I can see no description about it.

    2. Are there any example schematic of DP83822 to connect with AFBR-59E4APZC(Broadcom) as SFF/FP transceiver?

    Regards,
    Noriyuki Takahashi
  • Hi Noriyuki-san,


    I have responded in details to your email. I am closing this thread.

    Regards,
    Geet