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VCC and Vpass recommendation for TCA9543A

Miles Cernauskas
Prodigy 230 points

We want to implement a circuit like in the picture below, were the VCC is connected to the lower voltage (SD0, SD1) instead of the SDA voltage, in this case 1.8V and we are not sure if the Vcc must be 1.8V or 3.3V, we have some concern that Vpass is too close to 1.8V, and in the other case connecting to 3.3V we have the concern that the voltage diference between Vcc and SD0 can have some how closed the fets,  so can you help us clarify if the design connectivity is OK or there is any risk? Thank you in advance.

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    TI__Expert 5140 points

    Hi Miles,

    Thanks for the question.

    For our I2C switches, we recommend that VCC be equivalent to the lowest voltage on the any of the channels. So in this case, 1.8V is the lowest voltage on both channels, so VCC would need to be 1.8V to avoid leakage issues. In this case, our VPASS¬ can be determined to be about 0.8V according to the following chart:

    Thanks,

    Siby