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Original question:

TCA9517: B side connect to B side through PCA9546 MUX

TCA9517: What will happen if connect VCCB to 1.8V?

Shaquille Chen
Intellectual 1770 points
Part Number: TCA9517

Hi Team,

As title, what will happen if connect VCCB to 1.8V?

Customer connect VCCA to 3.3V and VCCB to 1.8V. 

Shaq.

  • 0
    TI__Guru 73221 points

    Shaq,

    Most likely the device will be held in reset and will not operate. The datasheet mentions the power up circuitry will not enable B side drivers until it is above 2.5V, there is likely some margin here but 700mV is quite a big difference.

    Even if the device did work, the VoL of B side is 0.54V which is the same as the ViL spec for 1.8V defined by the I2C spec. There is no margin here at all.

    The customer should rework their board/schematic to resolve the Vcc rules.

    -Bobby