Question about Link Rate of LTC4331


Is the I2C link rate limited by the SCL frequency?

I am thinking of setting the link rate to 500kHz or 1MHz with the SCL frequency = 400kHz.

Which link rate (500kHz or 1MHz) is better?



  • +1
    •  Analog Employees 
    on Oct 15, 2021 11:59 AM

    Hi Kazu, 

    Table 2 in the LTC4331 datasheet will be the guide to follow. A 400kHz SCL corresponds to the Fm I2C Class, which means a Speed Index of 5 or greater. 

    Let me edit this to add a detail... The clock width is reproduced by the LTC4331 pair. If Speed Index 8 is chosen (1MHz Link Rate), the SCL coming out will have the width of a Fm+ clock. It may be too narrow for the remote I2C devices to interpret at there probably isn't any advantage to do it. I'd recommend picking Speed Index 5-7.