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TCA9548A: the control register contents mess up after MDIO traffic sent.

Joey Zhuo
Prodigy 10 points
Part Number: TCA9548A


can the IC run beyond 400K bps?
can the IC use for MDIO channel switching?
can the pass through random data hit the I2C address and screw up the control register data?

Do you have any other 1x8 MDIO switcher, run up to 4 MHz?

  • 0
    TI__Guru* 75871 points

    Hi Joey,

    I'm not as familiar with the MDIO standard/spec however I believe its a push pull type of system and is typically run much faster than the 400kHz that our 9548A supports. 

    I2C spec states that I2C devices need to include a 50ns deglitch filter, so if any frequency goes above the 10MHz, then the 50ns filter would be able to keep the I2C device from seeing the data/clock traffic. Signals below this speed could pass through the 50ns filter though. This could potentially cause the I2C device to see I2C traffic which could inturn cause read/writes to the TCA9548A if the data pattern looked like the device address from the device's perspective. 

    "can the pass through random data hit the I2C address and screw up the control register data?"

    Based on the info provided above, I would guess this would be possible if the speed were faster than 400kHz but slower than 10MHz.

    "Do you have any other 1x8 MDIO switcher, run up to 4 MHz?"

    I am not aware of TI having an MIDO controlled switch. I would guess you would need to use a discrete MUX/switch which is controlled using the select pins to act as a MDIO switch.

    -Bobby