• State TI Thinks Resolved
  • Locked Locked
  • Replies 9 replies
  • Answers 2 answers
  • Subscribers 22 subscribers
  • Views 940 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Original question:

LSF0108: the LSF0108 issue

LSF0108: bidirectional buffer soluation for 5MHz CLK and DATA signal

Jason Dai
Expert 3720 points
Part Number: LSF0108
Other Parts Discussed in Thread: SN74LVC245A, TXB0104

Dear E2E,

we are looking for bidirectional buffer or level shift solution to handle 1v8 to 1v8 at 5MHz frequency signal.

Please help to propose a suitable solution.

BR,

Jason

  • 0
    TI__Guru* 97066 points
    Hi Jason,
    Can you provide a schematic or details of your system? What you have described does not indicate a level translator. Does one of the supplies change under certain circumstances?
  • 0 in reply to Emrys Maier
    TI__Expert 3720 points
    Hello Emrys,
    no schematic. We are looking for the bidirectional buffer to handle CLK and DATA signal. Just want to know if your team has suitable solution to propose?
    1v8 to 1v8 at 5MHz frequency signal

    BR,
    Jason
  • 0 in reply to Jason Dai
    TI__Guru* 97066 points

    Hey Jason,
    That's not a lot of details to go on.

    Pretty much any logic buffer can support 5 MHz, and multiple logic & translation families support 1.8V (AUC, AUP, LVC, TXB, TXS, LSF to name a few)

    If you're looking to buffer a signal -- ie redrive the signal to improve the signal integrity -- then you could look at the TXB family of translators. The improvement to the signal will be very dependent on the application.

    If you really want to improve signal integrity, I would recommend using a direction controlled buffer like SN74LVC245A (or any transceiver in our portfolio).

    It's pretty odd to see a CLK signal changing direction. Do you know what the application is?

  • 0 in reply to Emrys Maier
    TI__Expert 3720 points

    Emrys,

    Due to trace too long around 10cm to 15cm between LTE and SIM card, we are looking for a redriver to enhance the single.

    There are three signal, CLK, DATA, and Reset. The signal frequency is 5MHz and voltage level is 1v8.

    Please let me know any info you need to know and then you could suggest a suitable solution.

    BR,

    Jason

  • 0 in reply to Jason Dai
    TI__Guru* 97066 points
    Thanks Jason,
    These details are helpful -- I do need to know a couple of more things to make a suggestion:

    (1) Is the driver push-pull or open-drain?

    (2) Are there any pull-up or pull-down resistors on the communication lines? (these could be internal to a device on the line)
    (2a) What are their sizes?

    (3) Does the system controller have an available GPIO pin to provide direction control for the redriver?
  • 0 in reply to Emrys Maier
    TI__Expert 3720 points

    Emrys,

    Csutomer just care the automaticlly direction switch. others, they are ok either options.

    any suitable proposal?

    BR,

    Jason 

  • 0 in reply to Jason Dai
    TI__Guru 62600 points
    Jason,

    Automatic direction switching can be handled by TXB0104(4-channel device).
    From what I have seen from the conversation here, there is no translation happening (1.8 to 1.8V) and CLK signal which doesnt need direction change. This cannot drive large cap loads or provide drive strength >20uA.
  • 0 in reply to ShreyasRao
    TI__Expert 3720 points
    Shreyas,
    thanks for your reply.
    I will forward TXB0104 proposal to customer.
    Do you have any idea which solution or team i could reach to get more than 20uA driving current capability with automatic bidirectional control for DATA pin?

    BR,
    Jason
  • 0 in reply to Jason Dai
    TI__Guru* 97066 points
    Hey Jason,
    an automatic bidirectional driver must _always_ be weaker than the driver that controls it -- otherwise it would be impossible to switch it.

    For example, if you have a driver that can output 4mA, and you want to buffer it with a stronger driver, say one that can drive 16mA.... there's no problem if you do this with a direction controlled or unidirectional buffer, but if you use an autobidirectional buffer, then if the 16mA driver is forcing the line LOW, then how can the 4mA driver ever force the line HIGH again?