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TCA6416A: TCA6416A and partial power operation

David Cananzi
Prodigy 120 points

Part Number: TCA6416A

To whom it may concern,

We would like to operate the TCA6416A from a 3.3 V SMBus, but have it drive/receive 1.8 V IO. What is the power-on timing requirement? Does this device support partial power-on operation without leakage?

Thank you

  • 0
    TI__Genius 15345 points

    Hi David,

    For this family of devices the VCCP must be powered on first before VCCI otherwise the device could power on with a stuck bus. It is not so much of a timing requirement but a voltage level requirement. The voltage level for the VCCP to be considered powered on is 1.4V. This is the maximum voltage of the power on reset. Once VCCP has reached 1.4V you can power on VCCI. Depending on your power supply you can figure out the timing requirements for your system.

    The device does support partial power-on operation. There should be no back biasing from the VCCP to the VCCI supply.

    Best,

    Chris

  • 0 in reply to Chris Ayoub
    Prodigy 120 points

    Hi Chris,

    For this design we power VCCI before VCCP, but we hold the GPIO expander in reset until VCCI and VCCP power good is reached. Can that prevent a "stuck bus" condition?

    Thanks

  • 0 in reply to David Cananzi
    TI__Genius 15345 points

    Hi David,

    The stuck bus will only happen on some devices and before VCCP is powered. Once VCCP powers up the stuck bus should clear. Holding in RESET should be fine but might not even be necessary.

    Best,

    Chris