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UCD3138064: Confirmation I2C spec in datasheet

Johnny Chen
Expert 4910 points
Part Number: UCD3138064

Hi all,

I am asking for my customer.

Since the I2C specification defines 10kHz of minimum I2C speed, but I check the UCD3138064 datasheet does not specify about it (pic below).

May I confirm does the UCD3138064 device support all range of 10kHz~400khz I2C speed ? 

Thanks for the reply.

  • +1
    TI__Genius 17090 points

    The 064 is only a controller, so it dictates the clock speed.  So the choices are a nominal 100 KHz and a nominal 400 KHz.  Note that the rise time on the clock actually slows things down because it looks like a clock stretch to the UCD.  This means that the exact frequency will be a bit lower than the nominal.  

  • 0 in reply to Ian Bower
    TI__Expert 4910 points

    Hi Ian,

    I see what you are saying. Thanks a lot.

    However, the customer is using 064 to do communicate with their system. The communication frequency will be 10Khz~400Khz.

    In this situation, the device 064 will fail to communicate in the frequency 10kHz, am I correct ?

    Or it can be used in 10Khz communication without any problem ? May I double confirm it 

    Thanks and regards.

  • +1 in reply to Johnny Chen
    TI__Genius 17090 points

    Johnny, are you talking about the I2C interface on the UCD or the PMBus/I2C interface.  What I said before only applies to the I2C system, which is controller (master) only.  The PMBus/I2C interface when used in peripheral (slave) mode can of course run at 10 KHz.   I am using controller and peripheral instead of master and slave because these are the new names we are using now to make our terminology kinder and less offensive.