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PCA9306: TI PCA9306 waveform issue

Gary Chang
Intellectual 490 points
Part Number: PCA9306

Tool/software:

Hello TI team,

We are using the PCA9306 level shifter on the I2C bus, the SCH and waveform are as follows,

There is an abnormal rise at the low level, then we removed the IC, and there was no abnormality at the low level

Do you have similar experiences or any suggestions?

The measured waveform shows that it only occurs on the clock, the data signal does not have this issue

Thanks

  • 0
    TI__Guru 52166 points

    Hi Gary,

    It should not cause system issues if VOL is of no concerns. To improve, you may lower the VIL or IOL by increasing pull up resistance value on the Clock, thanks. 

    Best Regards,

    Michael. 

  • 0 in reply to Michael Ikwuyum
    Intellectual 490 points

    Hello Michael,

    Thank you for your reply

    Regarding this anomaly, we would like to know if it was caused by incomplete conduction of the internal MOS

    Or was this two-stage low-level rise caused by other factors?

    Thanks

  • 0 in reply to Gary Chang
    Guru 317450 points

    The PCA9306 is a passive switch, it can neither pull the line high nor low. This step cannot be caused by the PCA9306 itself.

    I suspect that there are multiple I²C devices driving the line low, or that some device changes its drive strength dynamically. Are you using any kind of I²C accelerator, or some other level shifter?