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TXB0104: Meaning of "high impedance" outputs

Lauren Mayfield
Expert 7915 points
Part Number: TXB0104
Other Parts Discussed in Thread: TXU0304, TXU0104, TXU0204

Hi team,


My customer is concerned about the outputs being in a "high impedance state". She wants to know if there are other states the outputs can be in during power-up and power-down, and if this is necessary to the operation of the part. She reads high impedance and becomes concerned about excess current draw.

Can you please elaborate on the high impedance state and if this is needed, and how this impacts excess current draw if any? If this is an energy storage application is there a way to reduce current draw?

Thanks!
Lauren

  • 0
    Guru 316690 points

    The high-impedance leakage currents are specified as IOZ. There is no excess current.

    To ensure that the outputs are in the high impedance state, pull OE low.

    Most applications have unidirectional signals and work better with a unidirection translator, i.e., TXU0104/TXU0204/TXU0304.

  • 0 in reply to Clemens Ladisch
    TI__Expert 7915 points

    Hi Clemens,

    Do the outputs need to be in a high impedance state? That’s her question. What are the trade offs if outputs are in high impedance state vs not? Do they need to be?

  • 0 in reply to Lauren Mayfield
    Guru 316690 points

    When the outputs are not in the high-impedance state, the drive either high or low. During power up, when the input signals might not be valid or when the TXB might not yet work correctly, that high/low state might be wrong for your circuit. (The TXB outputs are very weak, the output impedance is 4 kΩ. A wrong signal might be a problem, but the current will not be.)