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TXB0304: Schematics Check with regard to OE pin

Yuanchen Zhu
Intellectual 425 points
Part Number: TXB0304
Other Parts Discussed in Thread: TXB0302

Dear TI Expert,

  When using TXB0304, we are a bit confused with the datasheet description, which seems to have a conflict between two screen shot below and related description section, so we just would like to double check with you.

At the moment. we assume that we should pull OE high when we need all outputs working in 3-state mode, in the case of TXB0304, whlist pulling OE low would make outputs as in high impedance state.

Please help us check this as how we use it in our application(we use TXB0304 along with TXB0302 to change voltage level of QSPI signal from 3.3V to 1.8V bidirectionally):

Thanks. Looking forward to hear from you ASAP.

Regards,

Yuanchen

  • +1
    Guru 316760 points

    This is an error in section 11.2; it should say "keep /OE high" or "keep OE low".

    The three-state mode is the high-impedance state. (The three output states are low (GND), high (VCCx), and high-impedance.)
    The outputs are enabled when OE is high or /OE is low. The outputs are disabled, i.e., in three-state mode, when OE is low or /OE is high.

  • 0
    TI__Mastermind 40216 points

    Hey Yuanchen,

    Thank you for bringing this to our attention. In addition to Clemens' response, this bug in section 11.2 will be addressed in the next datasheet revision for this device.

    Regards,

    Jack 

  • 0 in reply to Clemens Ladisch
    Intellectual 425 points

    Hello, Clemens

    As in section 11.2, what if we keep OE high in the way just that we just tie it to VCCA without other control signal? Is that feasible?

    And just for understanding, since you say that three-state mode is the high-impedance mode, what mode do we call it for the condition that outputs are enabled? Or why do we make high-impedance state as three-state mode, instead of just high-impedance? As in what scenario, would it become low or high even when OE is low.

    Regards,

    Yuanchen

  • 0 in reply to Yuanchen Zhu
    Guru 316760 points

    When OE is high, the outputs are enabled and will always drive either low or high. During startup, when the supply is below the minimum of 0.9 V, they might drive to the wrong value.