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P82B715: P82B715 Circuit I2C packet issue

Rahul Raj
Prodigy 30 points
Part Number: P82B715

Dear Team,

Kindly help me on this query,

I am using P82B715[TI] in my project. I am connecting two P82B715 in series connection over 30cm ribbon cable at 400Kbps Speed. On one end i have interfaced P82B715 with TMS320F28379DZWTS Microcontroller[TI].

Unfortunately there is an error in circuit i.e. SCL line of the Buffer is swapped between the buffered side and controller side[ Buffered Side[3000pF] of the I2c repeater is connected to onboard microntroller side and unbuffered side[400pF] connected to Cable Side] and SDA line is proper. Will this create any issue in the packet corruption or any issues?

I have atatched below images of my circuit for your reference.  Please

  • 0
    TI__Guru 69662 points

    Rahul,

    We will take a look at this and have a response by tomorrow. Thank you for your patience.

    Regards,

    Eric Hackett

  • 0 in reply to Eric Hackett
    TI__Genius 15345 points

    Hi Rahul,

    This is not recommended but could work with your pull up resistor combination. However, in this set up you get no benefit from using the P82B715. Do you have a second P82B715 on the other end of your cable?

    Best,

    Chris

  • 0 in reply to Chris Ayoub
    Prodigy 30 points

    Hi Chris,

    I have a second P82B715 connected on the other end of the cable with the correct circuit which connects to the I2C master . The TI controller i mentioned ,TMS320F28379DZWTS, acts as a slave.

  • 0 in reply to Rahul Raj
    TI__Genius 15345 points

    Rahul,

    That is good at least. Like I said this has the potential to work but is definitely outside of the spec for this device. When the cable side goes to pull low it will only be able to draw 2.6 mA of current at a max. Where as the buffered side if set up correctly should be able to sink 30 mA of current. This is what allows it to drive a much stronger load.

    With how small your cable and pull up resistors are this might be enough current to drive a low but you will have to test that for yourself.

    Best,

    Chris