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TXB0104: Power down of one side of the translator

william von novak
Prodigy 20 points
Part Number: TXB0104

In our application we will be powering down one or both sides of the level translator.  Our options are:

1) Connect switchable power to VCCA and VCCB, then power down both the translator and the devices connected to it

2) Connect nonswitchable power to VCCA and VCCB, then power down only the devices connected to it

Will both methods work?  Which is the preferred method?

  • 0
    TI__Guru* 97046 points
    Hi,
    I have asked our translation expert to take a look and get back to you.
  • 0
    TI__Guru 62180 points
    William,

    welcome to e2e !
    what is switchable and nonswitchable power?
    Powering down both the translator and devices will result in most power savings, and would not cause issues to the system.
  • 0 in reply to ShreyasRao
    Prodigy 20 points

    Switchable is power that is switched to conserve energy.

    Nonswitchable power is power that is always on.

    My question is basically this - 

    I would like to depower one side of the device at a time, to allow for shutting down specific power domains within our design.  As an example, consider the case where both sides are powered on and running.  Then, to save energy, the system depowers VCCB, so that VCCA (and all the devices it is driving) remains powered, and VCCB (and all the devices it is driving) is depowered.   Is this OK?  The data sheet contains this warning:  "During operation, ensure that VCCA ≤ VCCB at all times" which would seem to indicate that that is not OK.

  • 0 in reply to william von novak
    TI__Guru 62180 points
    The datasheet warning is valid during the active operation of the device.
    during ramp up and ramp down, it is fine to have Vccb power down first and then Vcca or vice-versa.
    when either the Vccb or Vcca is powered down to 0V, the IO ports are in hi-z.