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Original question:

SN74HCT541: Change of data sheet specifications (thermal information)

SN74HCT541: output state of SN74HCT541

Hangjie Wang
Intellectual 960 points
Part Number: SN74HCT541
Other Parts Discussed in Thread: SN74LVC1G34, SN74HCS244, , SN74AHCT08, SN74AHC08, SN74AHCT240, SN74AHC240, SN74LVC1G97

Hi team,

I understand that most TI buffers' output are 3 state, but in our applications, high resistance state is not expected, could you pls help to confirm whether there is a buffer without a high impedance state, 8 channels are the most appropriate.

Thanks a lot.

  • 0
    TI__Guru* 96842 points

    Hi Hangjie,

    Any device with a 3-state output can be operated without ever going into the high-impedance state - just tie the OE\ pin to ground.

    If you just need a single channel buffer without 3-state, the SN74LVC1G34 is a good option for most applications. For multi-channel applications (up to 8 channels), I'd probably go with the SN74HCS244 or SN74LVC244 and just tie off the OE\ pin.

    I see that you posted under the part number SN74HCT541 -- do you need a TTL-compatible device? What exactly does the device need to do?

  • 0 in reply to Emrys Maier
    TI__Intellectual 960 points

    Hi  Maler,

    Thanks for your reply, there is an application that needs to turn off all outputs through OE pin, and the output should be logic low instead of high impedance, can you please help me to confirm whether there is a logic device(Q1) that can meet this requirement, thanks.

  • 0 in reply to Hangjie Wang
    Guru 280180 points

    If you can reverse the polarity of the enable signal, then this can be implemented with AND gates (e.g., SN74AHC08, or SN74AHCT08 for TTL signals).

    If you need an active-low enable signal, the you have AND gates with one inverted input. This exists as a single-channel device (SN74LVC1G97), or you can put inverters (e.g., SN74AHC240/SN74AHCT240) in front of AND gates.

  • 0 in reply to Hangjie Wang
    TI__Guru* 96842 points

    Typically this is handled by adding a pull-down resistor at the outputs that need to be LOW when the output is in the high-impedance state. A 10kohm resistor can be used in many cases.