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TCA9543A: Power on the I2C but not on Vcc

JLA
Intellectual 2535 points
Part Number: TCA9543A

Hello, 

A customer of mine asks what is the consequences if they have power in I2C bus but not on the TCA9543A?

We didn't manage to find it out from the datasheet.

I noted in a thread that it might be issues knowing the states of the I2C pins if Vcc not ramped properly, I suppose that is valid in this case as well?

Best regards

Jorgen

  • 0
    TI__Guru 73911 points

    Hey Jorgen,

    The device should be HI-Z while the device is unpowered.

    "I noted in a thread that it might be issues knowing the states of the I2C pins if Vcc not ramped properly, I suppose that is valid in this case as well?"

    It depends on the Vcc ramp rate. We have recommended power supply ramps at the end of the datasheet on the bounds of the ramp rate.

    There shouldn't be any problems with the I2C lines powering up before Vcc for this device.

    Thanks,

    -Bobby