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ADC121C021-Q1: Tr/Tf min time

Shinji Tsuji
Genius 13419 points
Part Number: ADC121C021-Q1

Hi team,

Tr/Tf of I2C fast mode timing parameters are specified as 20+0.1Cb min. 

What is the potential impact if I violate this minimum value?

regards,

  • 0
    TI__Mastermind 24970 points

    Hello, 

    We do not look at performance/behavior outside of the specified parameters, thus we cannot state how a device will response or if it will respond the same each time. 

    My educated guess would be that the edges could not be recognized and lead to misinterpretation of data. 

    Regards

    Cynthia

  • 0 in reply to Cynthia
    TI__Genius 13419 points

    Hi Cynthia,

    The device need to recognize the edge of the signal?

    Could you confirm the background of why this is specifically defined as this format?

    In some cases I see high slew rate, so I would like to know the risk.

    regards,

  • 0 in reply to Shinji Tsuji
    TI__Mastermind 24970 points

    Correct, these parameters are for the SCL signal, if the device does not recognize that an edge happened in the SCL signal, then data will not be transmitted as expected. 

    This device was released over a decade ago, and was acquired to TI through National Semiconductor. There is limited information and access to background on such devices. This format for the spec is no longer used in current datasheets. 

    The note in the datasheet about Cb indicates that this device could have been initially intended for applications with long bus line connections. If this is of no concern for your application, then the minimum can be considered to be 20ns, which is more in line with common specifications for this parameter.  

    (1) Cb refers to the capacitance of one bus line. Cb is expressed in pF units

    Regards

    Cynthia