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Bidirectional, 15Mbit, isolated I/O - TXS0108e + ISO7242C + TXS0108e

Janusz Debski
Prodigy 70 points
Other Parts Discussed in Thread: TXS0108E, ISO7242C, SN74AVC2T245

I am working on bidirectional, isolated Digital I/O, which can be used as I2C or SPI. Each one DIO channel has to have full configuration flexibility (input or output, work with output push-pull or push-pull)

Digital I/O interface requirements:

- 15MBit data rate,

- bidirectional I/O (conf 1 – floating input; conf 2 – pushpull output)

- isolated 1.5kV

- 3.3V/5.0V logic level compatibility

Up to 1Mbit data rate, isolator with open-drain output is perfect.

Up to 15Mbit data rate I want to use 2x TXS0108e - configuration in attachment:

The idea is to split one bidirectional channel to two unidirectional channels (input and output) and pass both signal though digital isolator and then merge the signals also using TXS0108e part.

How will TXS0108e work with digital isolator (ISO7242C)?

Is there any risk in TXS0108e direction sensing mechanism in this application? Do you have any recommendation for 15Mbit bidirectional DIO?

  • 0
    TI__Expert 6430 points

    Hi,

    TXS0108E is an auto-sensing directional translator. If A1 and A2 are connected together, TXS0108E could be abormal since B1 and B2 port will affect A1 and A2 status andvice versa.

    It is better to used direction-controlled translator. When data transfer from A port to B port, please disable the reverse input channel.

    I think SN74AVC2T245 can be used in your system for the specific application.

    Thanks

    Wei