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TCA9545A: ringing in the SCLK

Lacey Lin
Intellectual 2900 points
Part Number: TCA9545A

Hi team,

my customer use the TCA9545 as below:

But sometimes the clock is missing and the I2C communication failure.as below:

They check the SCLK and find there is ringing in the failing edge.

Can you help to analyze if the ringing will disturb the TCA9545 and cause the SCLK missing? If so, any comment to eliminate the ringing?

If this is not caused by the ringing, what may be the cause for this?

Lacey

Thanks a lot!

  • 0
    TI__Guru 73221 points
    Hey Lacey,

    "Can you help to analyze if the ringing will disturb the TCA9545 and cause the SCLK missing? If so, any comment to eliminate the ringing?"
    Are you currently seeing missing/extra clock pulses?
    What is the time difference between between those bumps on SCL?
    Are the slaves on the bus threshold triggered or slew rate triggered? Most slaves are threshold triggered so they need to below/above a certain value before they register a low/high.

    "If this is not caused by the ringing, what may be the cause for this?"
    Some of the signal looks like it is noise, possibly adding more capacitance on the 3.3V rail could help with this. Some of it also just looks like the affect of the pass FET architecture the device has.

    Thanks,
    -Bobby