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PCA9515B: connect to TCA9517 directly

K.Hamamoto
Guru 12155 points
Part Number: PCA9515B
Other Parts Discussed in Thread: TCA9517

Hi

Our customer would like to connect this device to TCA9617 directly. Because PCA9515B is used on the re-used board and TCA9517 is used on new board.

They connects that two board which are the re-used board and new board with I2C. The re-used board can not be redesigned. 

On the other hands, it is not allowed if the two PCA9515B is connected in series. (This is mentioned on the datasheet at page 8.)

Is it possible to connect PCA9515B and TCA9617 directly?

Regards,

Koji Hamamoto

  • 0
    TI__Intellectual 1540 points

    Hi K.Hamamoto,

    usually this question can be answered by looking at the V_OL levels of the device in order to avoid lock ups. The PCA9515B datasheet is a bit older than our current devices and I'm not able to find the information I'm looking for. I will discuss this tomorrow with my team members and come back to you. as soon as possible!

    Kind regards
    Dierk

  • 0
    TI__Intellectual 1540 points

    Hi K.Hamamoto,

    thank you for your patience! It is possible to connect the TCA9517 A-side to any of the PCA9515B sides. Whats not working is connect the TCA9517 B-side to any of the PCA9515B Sides.

    If you take a look at the V_OL level you can usually determine the side operateing with a static voltage offset. 

    The TCA9517 is asymmetrical, the B-side has a static voltage offset:

    The PCA9515B is symmetrical, both the A and B-side can have a static voltage offset:

    A more detailed explanation why two sides with a static voltage offset can not be connected can be found in chapter 5 Description (continued) on page 3 of the TCA9517 datasheet.

    I hope this helps you out. Let me know if you have further questions.

    Kind regards

    Dierk