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SN74LVC2G17: Bidirectional

Jose Manuel Vidal Rico15
Intellectual 526 points
Part Number: SN74LVC2G17
Other Parts Discussed in Thread: TXB0102, TXS0102, SN74LVC1T45

Hello,

I was selecting a transceiver to convert TTL logic from 5V to 3V3...and I selected SN74LVC2G17...but now i am not sure about:

- Is this IC bidirectional?.

- What means...Allows voltage on the inputs and outputs when VCC is 0 V...???

Thanks in advance.

Jose.

  • 0
    Guru 317360 points
    This device has two unidirectional buffers, which are completely separate.

    Why are you asking whether it is bidirectional? Your description "from 5V to 3V3" implies that you do not need bidirectionality. Or do you also want to convert from 3.3 V to 5 V?

    The Ioff feature allows this chip to be powered down even if other devices connected to its I/Os are not.
  • 0 in reply to Clemens Ladisch
    Intellectual 526 points
    Dear Clemens,

    Thank for your swift reply.

    I was trying to connect this IC to UART connection (TX & RX) between 2 uC with differents logic levels (5V<->3V3). Is that possible with that IC?.

    Thanks in advance.

    Jose
  • 0 in reply to Jose Manuel Vidal Rico15
    Guru 317360 points
    You have two unidirection signals.

    Downconverting is possible if the buffer runs with VCC = 3.3 V, because its input is overvoltage tolerant.
    Upconverting is not possible, because it would have to run with VCC = 5 V (and this two-gate chip has only one VCC), and a 3 V input would not be high enough.

    If you want to use a single device, you can use a bidirectional 2-channel voltage translator like the TXS0102 or TXB0102.
    You could also use two single-channel unidirectional devices, e.g., SN74LVC1T45 for upconverting, and any normal LVC buffer for downconverting.

    Why did you select a Schmitt-trigger buffer? Do your signals have slow edges?
  • 0 in reply to Clemens Ladisch
    Intellectual 526 points
    Hello,

    I selected Schmitt-trigger in order to avoid possible noise in the signal.

    Thanks for all.

    Jose.