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DS125BR800: EEPROM Reading Settings for DS125BR800

Ogoshi Tomoki
Prodigy 30 points
Part Number: DS125BR800
Other Parts Discussed in Thread: DS280BR820

Tool/software:

Hi

I am considering using the DS125BR800 IC with an EEPROM.
In the datasheet, when ENSMB is set to float, it reads 'Read External EEPROM (Master SMBUS Mode)'.
However, just below that, it states that when SNSMB is 1 and READ_EN is low, it 'starts the load from the external EEPROM'.

Will setting READ_EN low cause the EEPROM to be read even when ENSMB is 1?

Also, please explain the difference in operation when setting READ_EN low in the case where ENSMB is float versus when it is 1.

Furthermore, regarding TPOR's 'Time in which a device must be operational after power-on reset',
does this refer to the time required to complete the EEPROM read when READ_EN is held low at all times,
or is it the time for the device to power up and complete the preparation for reading the EEPROM?

  • 0
    TI__Mastermind 37633 points

    Hi Tomoki-san,

    1. EEPROM load will only occur in "Master SMBus Mode".

    Please note that as described in the SMBus mode of the data sheet, the SD_TH pin (pin 26) will remain active unless the override bit for this pin is set.

    2. This is the maximum time required for the device to start responding on SMBus after POR.  Note that this value is referenced directly from SMBus specification.

    Thanks,

    Drew

  • 0 in reply to Drew Miller1
    Prodigy 30 points

    Hi, Tahnk you for your relpy.

    "2. This is the maximum time required for the device to start responding on SMBus after POR."

    However, is there a specification for the time it takes for the settings from the EEPROM to be reflected in the Redriver after the POR time?

    I am concerned about how long to take for the initialization time when READ_EN is always Low, and when to start communication afterward.

    I consider "initialization time" as "POR (max 500ms)" + "time to write the Redriver's setting values."

    For example, is there any information regarding the time it takes for the settings to actually be updated after rewriting the register values via I2C (from the last Ack)?

    If there is any other information related to the design of the initialization time, please let me know.

  • 0 in reply to Ogoshi Tomoki
    TI__Mastermind 37633 points

    Hi Tomoki-san,

    I don't have this data for this device.  

    DS280BR820 uses the same EEPROM structure as DS125BR800, and I would expect load time to be comparable.

    Thanks,

    Drew

  • 0 in reply to Drew Miller1
    Prodigy 30 points

    Hi, Thank you for your reply.

    I have one additional question about the EEPROM.

    I want to turn on Signal detection as mentioned in the datasheet section 8.3.2.1.1 to use the 9.2Gbps frequency band.

    Since I cannot prepare an SMBus Master, I would like to set this configuration in the EEPROM for the Redriver.

    However, the register map for the EEPROM does not specify the areas where I can set:

    1. Write registers 0x0D[1]= 1'b, 0x14[1] = 1'b, 0x1B[1] = 1'b, 0x22[1] = 1'b //* CH0 - CH3

    2. Write registers 0x2A[1]= 1'b, 0x31[1] = 1'b, 0x38[1] = 1'b, 0x3F[1] = 1'b //* CH4 - CH7

    Does this mean that the Signal Detection configuration cannot be set in the EEPROM?

    (Does this include the Reserved areas as well?)

    Our configuration assumes a 1-to-1 connection between the Redriver and the EEPROM.

  • 0 in reply to Ogoshi Tomoki
    TI__Mastermind 37633 points

    Hi Tomoki-san,

    Only bits from the register map with "EEPROM Bit" = "Yes" are included in the EEPROM map.  Other bits cannot be configured through EEPROM.

    Thanks,

    Drew