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TCA9803: TCA9803 - Potential skew between SDA and SCL output

Austin Allen
Intellectual 2595 points

Part Number: TCA9803

Hello,

On page 6 of the datasheet, I see specs for "Propagation delay high-to-low" and "Propagation delay low-to-high" for "Port A to Port B" and "Port B to Port A".

I am looking to find if there is a maximum possible "skew" that could exist between SDA and SCL on the output of this device. For example, is it possible for SDA to experience a propagation delay h-to-l of 75ns while the SCL experiences a propoagation delay h-to-l of 200ns thereby creating a 125ns "skew"? Or, is this propoagation delay largely fixed between the two paths and more of a device-to-device variation?

Thank you,

Austin Allen  

  • 0
    TI__Intellectual 1735 points

    Hi Austin,

    No we do not specify channel-to-channel skew between the SDA and SCL paths in the datasheet.

    Your example is not correct. Since the two channels use similar circuitry on the same die, their propagation delays would normally be expected to track each other, and the within-device skew is likely smaller than the full typical-to-maximum spread. However, this matching is not characterized or guaranteed in the datasheet. Differences in SDA and SCL loading, bus capacitance, pull-up resistance, supply voltage, and temperature can also contribute to the measured skew.

    Thanks

    Brian