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Original question:

TXS0102- Output voltage level

TXS0102: TXS0102YZPR - usage with external sensor on 1m wire, 2.2K Ohm pull-up, 3.3V (SHT35)

Achim Kraus
Prodigy 20 points
Part Number: TXS0102

Tool/software:

I try to connect a Sensirion SHT35, 1m wire, 2.2K ohm pull-up (internal at the sensors wire end), 3.3V to a Nordic Semiconductor Thingy:91X.

That Thingy:91X uses a TXS0102YZPR to switch from internal 1.8V IO to the external 3.3V IO for I2C. General, that works well for short wires. Trying to connect a SHT35 on a 1m wire fails. It's possible to connect that to other device (e.g. nRF9160 feather), but for now I didn't find a way to use it with TXS0102YZPR of a Thingy:91x.

Is that possible?

  • +1
    Guru 316420 points

    Yes; the TXS0102 is optimized for high data rates and short traces, and does not work well with long cables. (It's not a good choice for such development boards.) I'd guess that the cable's capacitance/inductance introduces ringing, which falsely triggers the TXS's edge accelerators. It's also possible that those 2.2 kΩ pullups are too strong for the 1.8 V master. (Check with an oscilloscope if the low-voltage level is too high or if there are oscillations.)

    Try removing the pullups, and use a much shorter cable.

  • 0 in reply to Clemens Ladisch
    Prodigy 20 points

    For the product idea it's not possible to use shorter cables nor is it possible to replace the pull-ups.

    I will try to do the analyzes with the Osci. If it doesn't work, I guess exchanging the Thingy:91X with a feather (without the TXS0102YZPR) will be the way to go.