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PCA9544A: PCA9544A : Cb (total bus capacitance of one bus line in Pf)

King Tsai
Intellectual 2495 points
Part Number: PCA9544A

Hello, Team

according to the datasheet page6,

'

"total bus capacitance of one bus line"

Does it mean SDA/SCL allow 400pF not including  each channel SD0/SC0、SD1/SC1、SD2/SC2、SD3/SC3 and calculate C-Load separately?

Or Calculate C-load including each slave-channel (SD0/SC0、SD1/SC1、SD2/SC2、SD3/SC3)? (No matter master side / slave side voltage)

  • +1
    TI__Genius 15345 points

    Hello,

    This will all depend on which channel is selected. If you don't select any channels to be enabled then your bus capacitance will just be the SDA/SCL bus.

    If you select a specific channel on the device then you have to include the bus capacitance of the selected channel when you calculate total bus capacitance.

    The 400pF you see in the datasheet is a requirement for I2C communication and your total bus capacitance cannot exceed that value. With this device you can only select one channel at a time so you only have to calculate the total bus capacitance with one channel at a time. Make sure that none of the buses exceed 400 pF.

    Best,

    Chris