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SN74AXCH8T245: data rate for Vcca = 1.8V and Vccb = 3.3V

Hans
Genius 12725 points
Part Number: SN74AXCH8T245
Other Parts Discussed in Thread: SN74AXC1T45, TXS0206

Hello Team,

according data sheet the SN74AXCH8T245 can support "Up to 380 Mbps support when translating from 1.8V to 3.3 V" (front page).

What is the maximum data rate for Vcca=Vccb=1.8V, please?

Thanks and Best Regards,

Hans

  • 0
    TI__Mastermind 42670 points
    Hi Hans,

    At this point, would they not just want to use a buffer?
  • 0 in reply to Dylan Hubbard
    TI__Genius 12725 points
    Hi Dylan,
    this is not the answer to my questions...
    Also the data rate for SN74AXC1T45 from your proposed AXC family is not specified for Vcca=Vccb=1.8V.

    Thanks and Best Regards,
    Hans
  • 0 in reply to Hans
    TI__Mastermind 42670 points
    Hi Hans,

    Data rate is an interesting specification because it depends on the system designers tolerance for various parameters, so will generally need to be tested in the specific application environment for the clearest understanding of signal integrity.

    I can say that this device could support up to 210Mbps data rate, but this will be highly dependent upon system design factors.

    Is there a particular data rate that you are considering using this device for at this voltage? Is this for a specific protocol?

    What is the system application that you are considering using this device for?

    Do you have a schematic snippet you can share?
  • 0 in reply to Dylan Hubbard
    TI__Genius 12725 points

    Hi Dylan,
    I am looking for something like http://www.ti.com/product/txs0206-29 

    Best Regards,

    Hans

  • 0 in reply to Hans
    TI__Mastermind 42670 points
    Hi Hans,

    So you are wanting that functionality or are we still discussing data rate?
  • 0 in reply to Dylan Hubbard
    TI__Genius 12725 points

    Hi Dylan,

    yes, that functionality, but with higher data rate of 210Mbit/s. This is required by SD 3.0 standard. The idea was to build this discrete with the SN74AXCH8T245.

    Best Regards,

    Hans

  • 0 in reply to Hans
    TI__Mastermind 42670 points
    Hi Hans,

    Since that device is so application specific, we don't currently have a similar device that has data rate to support SD 3.0. You will have to go with a discrete solution. The TXS family of translators are auto bidirectional (which is what the TXS0206 has integrated in it), but the AXC family is direction controlled. The AXC family will provide the fastest data rate. Is it planned to translate from 1.8 V to 1.8 V and 1.8 V to 2.9 V?
  • 0 in reply to Dylan Hubbard
    TI__Genius 12725 points

    Hi Dylan,

    exactly! From 1.8V to 1.8V and from 1.8V to 3.0V (or 2.9V). The SN74AXCH8T245 can do the 1.8V to 3.0V at 210Mbps easily but can it also do this data rate for 1.8V to 1.8V?

    Best Regards,

    Hans

  • 0 in reply to Hans
    TI__Mastermind 42670 points

    Hi Hans,

    Sorry for the delay, I wanted to get into lab and get some measurements for you. I hate to keep saying it, but data rate @ 1.8 V to 1.8 V is heavily dependent on their system and system requirements. I did take a measurement for it at 200 Mbps (my function gen only went that fast unfortunately), but its not far off from 210 Mbps. See below: 

    I just used a quick set-up so it isn't the best signal integrity (I expect it to be better in their actual design), but again the results will likely be different in their system depending on the load and possible board parasitics. It could be better or worse, but I recommend them to take care on the board layout as to keep the load capacitance as low as possible.