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TCA6416A: Power up sequence of VCCI and VCCP

Lacey Lin
Intellectual 2900 points
Part Number: TCA6416A

Hi team,

My customer wants to know if there is requirement for the power up sequence of VCCI and VCCP?

Lacey

Thanks a lot!

  • 0
    TI__Guru 72621 points

    Hey Lacey,

    The device will remain in reset until VCCP is above POR so VCCP should power on second. If this is not possible you can also tie the reset pin to a pull up resistor on VCCI and power on VCCI after VCCP.

    Thanks,

    -Bobby

  • 0 in reply to BOBBY
    TI__Intellectual 2900 points
    Hi Bobby,
    So the VCCI should be after the VCCP.
    Is there any requirement for the delay between the VCCI and VCCP?

    Lacey
    Thanks a lot!
  • 0 in reply to Lacey Lin
    TI__Guru 72621 points
    Hey Lacey,

    I would recommend VCCI be pulled up to atleast 70% of Vcc of the I2C line before VCCP reaches POR just to be sure the device starts up seeing the I2C lines are high.

    Once again, if the customer cannot do this they can tye the reset pin to VCCI so that the device is initialized after VCCI powers up.

    Thanks,
    -Bobby
  • 0 in reply to BOBBY
    TI__Intellectual 2900 points

    Hi Bobby,
    So the sequence is the VCCI firstly, and then the VCCP. Is it correct?
    And if customer don't pull up the Reset pin to VCCI.
    What's the sequence of the RESET according to the sequence of VCCI and VCCP?

    Lacey
    Thanks a lot!

  • 0 in reply to Lacey Lin
    TI__Guru 72621 points
    Hey Lacey,

    "So the sequence is the VCCI firstly, and then the VCCP. Is it correct?"
    This is what I would recommend as VCCP controls the reset/initialization of the device it should be powered on last.

    "What's the sequence of the RESET according to the sequence of VCCI and VCCP?"
    Typically you would want to tie reset to one of the Vcc pins (you can tie a GPIO to it to pull low directly if needed for the mcu to control while still tied to a Vcc pin). If for some reason (I can't think of any reason why you wouldn't want to tie it to VCCI/VCCP) then reset should be powered on last.

    If tied to VCCI then it doesn't matter what side gets powered on first (this makes things a lot easier because we don't care about power sequencing any more).

    Thanks,
    -Bobby
  • 0 in reply to BOBBY
    TI__Intellectual 2900 points
    Hi Bobby,
    Thanks for your reply!
    So It should be OK if we tie the VCCI, VCCP and the pull up the reset to a same VCC?

    Lacey
    Thanks a lot!
  • 0 in reply to Lacey Lin
    TI__Guru 72621 points

    Hey Lacey,

    That should be fine as well.

    Thanks,

    -Bobby