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About SN74LVC1G38

Shu-Cheng LIN
Guru 11785 points

Other Parts Discussed in Thread: SN74LVC1G38, SN74LVC1G00, SN74AHC1G00, SN74LVC1G97, SN74LVC1G98

Hi Sir,

Sorry to bother you.

We would like confirm if no VCC, what is the SN74LVC1G38 output state??

Because we have use SN74LVC1G00, Looks the output is pull low when no power.

It's make our device error....

So we are searching that output is Hi-z or Float at power off.

Could you share your experience for us??

Thanks!!

 

  • 0
    Guru 326790 points

    Both the SN74LVC1G38 and the SN74LVC1G00 have Ioff protection, i.e., without power, their outputs have high impedance (not pulled low).

  • 0 in reply to Clemens Ladisch
    Guru 11785 points

    Hi Clemens,

    Thanks for your reply.

    One more question.

    Because we already use SN74AHC1G00 and would like extend to new project.

    I couldn't saw Ioff protection at SN74AHC1G00 datasheet.

    So SN74AHC1G00 still have Ioff protection feature??

    Thanks !!

  • 0 in reply to Shu-Cheng LIN
    Guru 326790 points

    The absolute maximum ratings of the AHC device specify VCC+0.5V for the output voltage, i.e., without power, there must be no signal at the output.

    It might be possible to add a series resistor to the output to reduce the clamp current to an allowed value, but this would make the output slower, and would require that the VCC line is able to sink that current without floating up, even when switched off.

    Is there any reason to stay with AHC, and not switching to the LVC family?
    (And when using LVC, take a look at the SN74LVC1G97/SN74LVC1G98 devices, which are more flexible than a NAND.)