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LSF0204: Drive Strength for 10-foot wire harness

Michael T Schneider
Expert 3780 points
Part Number: LSF0204
Other Parts Discussed in Thread: SN74ALVC164245, LSF0108, TXU0104, TXU0204

Team, 

I am wanting to see if you can help me with integrating 2 parts together SN74LVC164245 and LSF0204. I am building a module that needs to interface with another module that has a SN7aLVC164245 level shifting transceiver on it. I am wondering if I can use an LSF0204 to level shift and drive a 10-foot wire harness to the module that has the SN74LVC164245.

Another piece of info you may need is that I am trying to translate from 1.8V to 3.3V TTL back and forth

  • 0
    TI__Mastermind 42640 points

    Hey Michael,

    No, the LSF0204 device has no drive of its own due to its passive FET architecture. Are all the signals going in one direction?

  • 0 in reply to Dylan Hubbard
    TI__Expert 3780 points

    Dylan, 

    thanks for the quick relpy!

    What I am trying to do is connect an FPGA with 1.8V outputs to a sn74alvc164245.

     

    There are 8 connections:

    2 x lines for a single ended Rx/Tx Serial bus RS-422 like to the sn74alvc164245

    6 x lines for a single ended parallel command buss from the sn74alvc164245

     

    These signals would be transmitted down a 15ft (30awg) wire harness to the sn74alvc164245 and visa-versa for the LSF0108 component.

     

    I would like to insert a LSF0108 or multiple LSF0204s to handle the voltage level shifting.

     

    Does this answer your question?

  • 0 in reply to Michael T Schneider
    TI__Mastermind 42640 points

    Hey Michael,

    I think I'm following. I actually recommend using a combination of TXU0104 and TXU0204 for this. These translators are actually buffered and are better suited for driving the cable. They also have schmitt trigger inputs to clean up the signals from the ALVC translator.

  • 0 in reply to Dylan Hubbard
    TI__Expert 3780 points

    Hey Dylan, 

    can you provide some clarity on your suggestion? Trying to work this out as the TXU0104 and TXU0204 as both provide less current (Drive and Sink ) than the LSF0XXX family of parts according to the absolute max ratings in the datasheet. 

  • 0 in reply to Michael T Schneider
    TI__Mastermind 42640 points

    Hey Michael,

    Please take a look at these training videos on LSF to see how it functions. This should help illustrate what I've been saying about it not providing any drive of its own. The Abs max table provides stress ratings and isn't the correct table to reference in this exercise, instead referencing the Recommended Operating table is more applicable.