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DS80PCI800 / READ_EN in SMBus Slave Mode

Toshiyuki
Mastermind 7075 points

Other Parts Discussed in Thread: DS80PCI800

Hi,

Customer is using DS80PCI800 as setting READ_EN=H in SMBus Slave Mode.

However, the latest datasheet(Rev,G) says, 「in SMBus Slave Mode, this pin is not used. Leave it floating」.

Is there any problem setting READ_EN=H ?

Best Regards,

Kato

  • 0
    TI__Mastermind 29655 points
    Hi Kato-san,

    Pin 26 has two different functions, depending on which mode of operation you are in. If you operate in SMBus Master Mode (ENSMB = F), then Pin 26 is used for READ_EN. If you operate in SMBus Slave Mode (ENSMB = 1), then Pin 26 is used for SD_TH, and you will not have access to READ_EN. There is no issue with tying Pin 26 = 1 when in SMBus Slave Mode. By doing this, you change the assert/de-assert threshold to be 190 mVpp (Assert), 130 mVpp (De-Assert). Usually it is advised to keep the assert/deassert level as floating for the default Assert/Deassert level, which is why we recommend to keep the pin floating.

    Pin 26 is still being used in Slave Mode and Pin Mode. The distinction that we make is that when operating in these modes, the pin is used for SD_TH and does not have any READ_EN functionality.

    Apologies for the confusion.

    Thanks,

    Michael