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SN74AVC32T245: Dynamic Direction Change Control Delay

Owen Mears
Expert 5115 points

Part Number: SN74AVC32T245

Tool/software:

Hello,

My customer has the following question:

I have another questions  consult, we have case requires dynamic direction change control from FPGA.
  1. Do we need extra control of OE pins before reverse direction or only direction pin change is needed?
  2. How to evaluate the direction turnaround needed waiting times?
There are description in the datasheet about “enable times”
Is this parameter describes the total delay of  A->B transmitting to B->A transmitting transition?
Thank you,
Owen
  • 0
    Guru 327530 points

    The /OE and DIR pins affect the outputs in the same way.

    1. You do not need to use /OE when changing directions; the DIR pin already disables the outputs on the new input side. You need to use /OE only if you want to disable the output drivers on both sides.

    2. As shown in section 10.2, the DIR time is the same as the disable/enable time. The propagation delay is added because in the worst case, the new input pin also must change its value. (For example, when the old direction was A→B, and the A input and B output pins were low, and you change to B→A, and the B input now gets a high signal applied, then both direction and value must change.)

  • 0
    TI__Mastermind 43540 points

    Thanks Clemens!

    Hello Owen,

    Seems Clemens answered your questions. Please let us know if there is additional help.

    Regards,

    Josh