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TCA6424A: Ticr and Ticf specification

Yusuke Mukuno
Expert 7395 points
Part Number: TCA6424A

Hi Expert,

My customer has an question about Ticr and Ticf specification.

Ticr and Ticf minimum spec in the datasheet::

20 + 0.1Cb (1)

(1) Cb = total capacitance of one bus line in pF

Why this spec is depended in the bus capacitance? Could you please let me know the detail of reason?

-------

*By the way, NXP specification is below,

tr(min) = 20 [ns]

tf(min) = 20 x (VDD/5.5[V]) [ns]

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Also, What is meaning T"icr" and T"icf"?

Thanks

Muk

  • 0
    TI__Mastermind 49110 points

    Those are system level specs that come from the I2C standard. The NXP version uses the I2C spec standard 2.6V. I believe our system specs come from the older version of the I2C standard (I found that version 2.1 has the spec you are referencing). I can put in a request to make the change  in the datasheet to reflect the newer standard but this is just a requirement from the I2C standard at the system level and not specifically our device.

    -Bobby

  • 0 in reply to BOBBY
    TI__Expert 7395 points

    Bobby-san,

    Sorry for bother you.

    customer has additional question.

    This spec come from old I2C standard. right?

    About your comment below,
    "I can put in a request to make the change  in the datasheet to reflect the newer standard
    but this is just a requirement from the I2C standard at the system level and not specifically our device."


    What is requirement from TCA6424A?
    Is it meaning, customer should refer and satisfy the datasheet spec that is old standard?

    Thanks

    Muk

  • 0 in reply to Yusuke Mukuno
    TI__Mastermind 49110 points

    Our device is not sensitive to fast fall times/rise times from either of the two I2C specs as long as the voltages are within the allowed operating conditions. The specs referenced are system level specs for the I2C bus based on I2C standards and not specifically the device itself.

    I'd recommend following the latest version of the I2C standard since its the most current if the customer wants to be I2C compliant.

    -Bobby

  • 0 in reply to BOBBY
    TI__Expert 7395 points

    Bobby-san,

    Thank you for your answer.

    Thanks

    Muk