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TCA9517: B side connect to B side through PCA9546 MUX

user4979899
Expert 3080 points
Part Number: TCA9517

Hi Sir,

As my understand, 2 pcs TCA9517 can't connect both B-side together.

And I want to double confirm if we add a NXP PCA9546 I2C MUX between both TCA9517 B side as below topology,

Is it workable?

Thanks

  • 0
    TI__Guru 62920 points

    Anne,

    You are correct that this won't work.  The problem is that the B side VOL is higher than its VIL (which is required for the buffer to work reliably with bidirectional communication).  PCA9546 uses a FET switch based architecture, so when signals pass through an active channel there is no "re-driving" of the voltages.  Since the switch is unable to reduce the VOL voltage, it cannot be properly resolved by a TCA9517 on the other side.

    If you can tell us more about the problem you are trying to solve with this set-up maybe we could help propose an alternative solution.  Also, you may want to try using our I2C Designer tool here:

    dev.ti.com/.../

    It allows you to enter in the interface parameters of various I2C devices and then will propose a solution.

    Regards,
    Max