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TCA9539 I2C input rise time on STANDARD MODE

Other Parts Discussed in Thread: TCA9539, PCA9539

TCA9539 has the maximum input rise time of 300ns.

Can TCA9539 connect to the standard mode device which has the maximum output rise time of 1000ns?

Best regards,

Daisuke

 

  • Daisuke-san,

    Edit:

    The TCA9539 DOES support standard-mode I2C with maximum rise time of 1000ns, which is per the I2C spec

    The TCA9539 does support fast-mode I2C with a maximum rise time of up to 300ns (per the I2C spec).

    Unfortunately, for fast-mode, we cannot recommend this, due to the way the TCA device reads the input on rising edges. If the rising edge is not fast enough, there is the possibility that the data will not be read.

    One way you might be able to get around this is to lower the pull up resistance. You would need to make sure that you do not violate the maximum input current of the TCA9539.

  • Hi Jonathan-san,

    Thank you for your reply.

    I understand that the I2C interface on TCA9539 supports only the fast mode, does not support the standard mode.

    Best regards,

    Daisuke

     

  • Daisuke-san,

    I mis-understood your post, my appologies.

    The TCA9539 DOES support standard-mode I2C with maximum rise time of 1000ns.

    The TCA9539 does NOT support fast-mode I2C with a maximum rise time of 1000ns (per the I2C spec)

    This is an error in our datasheet, that has been noted and will be corrected.

    I've updated my original post to reflect this

  • Hi Jonathan-san,

    Thank you for the correct answer!

    Best regards,

    Daisuke

     

  • Hi all,

    I am new to TI community. I need some help on using PCA9539.

    I am using this chip to enhance my IO pins by interfacing to PIC32.
    While trying to read from the chip ,I always get 0xFF ie, all Ones.

    If anyone has C code (without Linux please....raw device driver written in C ) for basic usage of this chip, kindly send it to me at tulsiramu@bel.co.in.

    Thanks in advance
    BLTR
  • Hello Thulashi,

    For new questions, we ask that you create a new thread so that we may assist you.

    However, we do not have raw code available that we can give you.

    If you create a new thread, I'll be happy to help you understand the proper procedure to read and write to the PCA9539.