• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Subscribers 34 subscribers
  • Views 285 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Original question:

TCA9517: Use case question

TCA9517: TCA9517

a b
Prodigy 190 points
Part Number: TCA9517

In regards to the TCA9517,....

What will the default behavior of the B-side bus if the A-side bus is left floating?  (VccA, SDCa, SCLa are all unconnected.  No pull-ups.  No supply.)

Is this a stable and reapeatable state?  (Or it undefined behavior?)

Thank you

  • +1
    Guru 317370 points

    When powered, I²C always requires pull-up resistors; the behaviour of floating inputs is undefined.

    But it is allowed to leave one side unpowered; see section 11 of the datasheet.

  • 0 in reply to Clemens Ladisch
    Prodigy 190 points

    I am looking at the July 2017 datasheet. 

    In section 5, there is a mention of "power-good-detect" circuit.  But there is nothing more said of it.

    Section 11 say's VccA must be above 0.8v before the driver will turned on.  So a float on VccA would mean the TCA9517 would not effect the B-side lines.