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TCA9544A: I got some questions about TCA9544A.

BJ Han
Expert 2035 points
Part Number: TCA9544A
Other Parts Discussed in Thread: PCA9544A, TCA9545A

Hi TI engineer,

I am using the MAX7367, but I would like to switch to TCA9544A(or PCA9544A) among TI products.

1. Are the two products compatible with each other? (Does not the circuit need to be modified?)

2. What is the operation sequence when accessing a slave device connected to each channel of the TCA9544A in the host?

-. Write operation sequence : Ex) channel 2 / Device address(0xe0) control byte(0x??) à Slave address (Slave device connected to Channel 2 of Mux)  à ………………..

-. Read operation sequence : ?? (Explanation of operation sequence such as write is required)

Thank you.


  • 0
    TI__Genius 16450 points
    Hello BJ Han,

    Thanks for the questions.

    Quick note concerning our PCA vs TCA devices. The TCA device family is the latest generation. It features lower voltage support, better power on reset performance (power supply ramping requirements) and other general improvements, and is the recommended family whenever possible.

    The MAX7368 is actually the closest cross to the TCA9544A. If you are using the MAX7367, the TCA9545A has the same pinout and same I2C address.


    With regards to your question on how to write or read. The two devices are identical, software-wise as well.


    For example, If you want to enable channel 0 (I am going to assume A0 = A1 = GND), then you would write:
    START, 0xE0 (0x70 + W), 0x01, STOP

    If you want to enable both channel 0 and 2, You would write:
    START, 0xE0 (0x70 + W), 0x05, STOP



    If you want to read, it's very similar, you do not provide any register address, simply pass the device address with the read bit set, an example of what to send is:
    START, 0xE1 (0x70 + R), <DATA FROM TCA9545A>, STOP



    Let's say you get an interrupt, and want to read the device to see what channel set the interrupt, you would write/read:
    START, 0xE1 (0x70 + R), 0x45 (data from TCA9545A), STOP
    This would mean that the interrupt input for INT2 is asserted. You can also tell from this that channels 0 and 2 are active/connected.