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Original question:

SN74AVC4T774: Logic forum

SN74AVC4T774: SN74AVC4T774

Rakshitha Y S
Prodigy 10 points
Part Number: SN74AVC4T774
Other Parts Discussed in Thread: TXU0304, SN74AXC4T774

Hi Team,

We are using "SN74AVC4T774PWR" level translator in our project. We want our circuit should be always enable, so we connected #OE pin to ground through 10K ohm resistor. Please review the below schematic and kindly share your feedback.

Early response is highly appreciated.

Thanks,

Rakshitha

  • +1
    TI__Mastermind 25680 points

    Hi Rakshitha,

    No concerns if not concerned about the state of the outputs during powering up (i.e can be unknown for either high/low until Vcc is fully ramped up, see the datasheet's section 11).

    If concerned, please see the newer upgrade SN74AXC4T774 instead, with a a more robust power sequence. You may also see TXU0304 for an easier implementation per the schematic, thanks.

    Best Regards,

    Michael.

  • +1
    Prodigy 10 points

    Hi Michel,

    Thanks for your early response,

    you are saying that, we should connect the #OE(Active low) to ground through 10K pull down resistor for default enable circuit. Please confirm

    For example, If I want my circuit always be enable, however If I connect the #OE(Active low) to pull up resistor through 10K resistor. Please let me know, the circuit will work(By default enabke).

    Anticipating an early response.

    Thanks and Regards,

    Rakshitha

  • +1 in reply to Rakshitha Y S
    Guru 260630 points

    During power up, before the supply voltage has reached its minimum, the outputs might have the wrong direction or output a wrong value. If you do not care about this, then you can always pull /OE low.

  • 0 in reply to Rakshitha Y S
    TI__Mastermind 25680 points

    Hi Rakshitha,

    It will work, but you may or may not observe a glitch until the VCC is fully ramped up i.e, during the short duration when the circuit is enabled prior to Vcc powered / ramped up. Hence, mainly during only power-up.

    If any concerns for the state of I/O or glitching before ramping up (no concerns once Vcc is fully ramped up for normal operation), please see AXC or the TXU recommendation with a more robust power sequence, thanks.

    Best Regards,

    Michael.