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TXS0108E: I2C communication fail!!!

Paul Yeh
Genius 16185 points
Part Number: TXS0108E

Hi team,

Customer is having level-shifting allocation(TXS0108E) in their platform. And they designed for I2C interface. But they found I2C communication will be fail during operation.

So they would like to know is there any concern to use this device in I2C interface?

And they would like to know why there is different pull-up resistor value(4k or 40k) during different output drive? This device has the smart pull-up resisters dynamically change, so is it possible to impact I2C signal?

Do you have other solution which is P2P design and there is a certain value pull-high resister?  

Thanks

  • 0
    Guru 316780 points

    The TXS0108E changes the pull-up resistance to reduce power consumption for low-level signals.

    The problem is most likely related to the TXS's edge accelerators. Do you have long traces or cables? Are there external pull-ups? Please show an oscilloscope trace.

  • 0 in reply to Clemens Ladisch
    TI__Genius 16185 points

    How to judge the trace is long or not ? 10inch, 15inch ?  There are no external pull-ups are on A-port and B-port.

    We can’t find any abnormal waveform and failure if we having oscilloscope to probe this bus. That’s why we think this might be electrical issue or something like that.

     Thanks

  • 0 in reply to Paul Yeh
    Guru 316780 points

    The trace is too long when its capacitance is so high that the edge accelerator is not able to raise the voltage completely.

    Can you show the I²C waveforms, on both A and B sides?