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I2C repeater or hot-swappable buffer?

luca turrini
Intellectual 300 points
Other Parts Discussed in Thread: TCA9517A, TCA4311A, P82B96, P82B715

Hi,

I'm designing a communication I2c system from board to board connected via cable.

Each system has a different power supply (with common ground), that power-up at different time; I intend to use on each side a TCA4311A or a TCA9517A that became connected in series.

Which part do you think is better for my problem?

Also consider that in my system I can't connect the enable pin at the same command, but each board drive it from themself.

Could you give me any suggestion?

Thanks

  • 0
    TI__Intellectual 2175 points
    Hi Luca,
    Can you give me an estimate of the cable length or the total estimated cable capacitance? The TCA4311A and TCA9517A can provide buffering up to 400pF of bus capacitance as per the I2C spec.

    If there is hot-swap requirement (chances of plugging the board out while I2C communication is happening) then TCA4311A is recommended device. If not, then TCA9517A is recommended.

    If the cable and board capacitance is much greater then 400pF then I recommend using the I2C bus extenders (P82B96 or P82B715).

    If you are using either of these devices on each side of the board, then you can use a GPIO to control the enable pin.

    Thanks,
    Rajan
  • 0 in reply to Rajan Arora
    Intellectual 300 points

    Hi Rajan,

    the cable on my application is an HDMI type with an approximate lenght of 50cm.

    The slave board could power-up when the master board is driving an I2c communication polling.

    The master board can't drive the enable pin of the slave board because I can't propagate this signal on the cable.

    thanks

    Luca

     

  • 0 in reply to Rajan Arora
    Intellectual 300 points
    Have got any news?