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DS250DF810: Daisy Chain Implementation and I2C Question

Jerry%20Leung
Intellectual 905 points
Part Number: DS250DF810

Hi Team,

I have a customer using the DS250DF810 and have a couple implementation questions below I am looking to get some insights for:

1) For the DS250DF810, if we enable this device to be a master on i2c during reset (via read_en_n), after reading the eprom data(signaled by assertion of all_done_n), will the device automatically switch to a slave mode so that a connected micro processor can reach the DS250DF810 via the I2C ?

2) We plan to have individual read_en_n  control for each device. In this scenario, If we like to daisy chain CAL_CLK_OUT to CAL_CLK_IN daisy chain mode, will assertion of read_en_n for one of the devices disrupt the CAL_CLK_IN to the down stream device ?

Thanks for the help in advance and best regards,

Jerry

  • 0
    TI__Guru* 93670 points
    Hi Jerry,

    1). When device is configured for SMBus Master Mode(EN_SMB=Float) then by asserting READ_EN_N this starts EEPROM read operation. To go back to SMBus slave mode - to interface to an external processor - we need to de-assert READ_EN_N AND pull EN_SMB high - through 1K-ohm Resistor.

    2). CAL_CLK_OUT is a buffered version of the CAL_CLK_IN and is not affected by READ_EN_N state.

    Regards,,nasser
  • 0 in reply to Nasser Mohammadi
    TI__Mastermind 29655 points
    Hi Jerry,

    In case you were asking about using Slave Mode AFTER EEPROM, perhaps this statement will help clear things up. If you wish to start up in EEPROM Master Mode, load settings from EEPROM, then have control of the device from an external MCU/MPU after EEPROM load, our redriver and retimer devices are all designed to revert to Slave Mode after the device has successfully completed reading its new default settings from the EEPROM at startup.

    Thanks,

    Michael
  • 0 in reply to Michael Lu (Santa Clara)
    TI__Intellectual 905 points

    Hi Micheal and Nasser,

    Thanks for the help in providing details. Some details our customer provided I want to run it by and see if there's any additional insights we can share:

    • We are planning to initialize DS250DF810ABVR retimer without EEPROM.
    • If initialization happens with retimer in slave mode only, what would be the initialization sequence and, complete register set to program so the device into operational state? This helps us confirm initialization time.

    Thanks for the help and insights,

    Best,

    Jerry

  • 0 in reply to Jerry%20Leung
    TI__Mastermind 43795 points
    Hi Jerry
    What datarate will be used in the DS250DF810 application. It may be possible to have the device power up and operate with default register values.

    Regards,
    Lee
  • 0 in reply to Lee Sledjeski
    TI__Intellectual 905 points

    Hi Lee,

    Thanks for the insights.  I want to follow up for our customer's application, they plan to use this device for 25.78125Gbps and 28.05Gbps rates. Would they be able to initialize this without EEPROM?

    Thanks for the help and best,

    Jerry

  • 0 in reply to Jerry%20Leung
    TI__Mastermind 43795 points

    Hi Jerry,

    This configuration would need to be programmed via SMBus registers or EEPROM.

    The 25.78125 and 28.05 Gbps rate would program with the following register values.

    0x60 = 74

    0x61 = C0

    0x62 = 20

    0x63 = C6

    0x64 = FF

    Regards,

    Lee