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TCA9534: Can be TCA9534 used with TCAL9539 using same I2C bus with 1MHz data rate?

Kazuya Nakai59
Guru 21515 points
Part Number: TCA9534
Other Parts Discussed in Thread: TCAL9539, TCA9535, TCA9543A, TMUX136

Tool/software:

Hello guys,

One of my customers is considering using TCA9534 for their new products.

At this moment, they have the following question.

Could you please give me your reply?

Q.
They want use TCA9534 with TCAL9539 using same I2C bus.
This TCA9535 address is different from TCAL9539 one.
Also they want to communicate to TCA9534 with 400kHz SCL clock and want to communicate to TCAL9539 with 1MHz SCL clock.

Is this usage problem?

Your reply would be much appreciated.

Best regards,
Kazuya.

  • 0
    TI__Mastermind 46928 points

    Hi Kazuya,

    Operating the I2C bus at 1 MHz might interfere with the slower TCA9534 which is only rated for 400kHz. 

    Best practice would be to use an I2C switch to control bus segments that separate the fast mode and fast mode+ lanes to the IO expanders. 

    A device such as TCA9543A would be perfect for this type of application. 

    Regards,

    Tyler

  • 0 in reply to Tyler Townsend
    Guru 21515 points

    Hi Tyler,

    Thank you very much for your reply.

    Could I ask you a few additional questions?

    Q1.
    I think you mean that this usage not recommended because it is unknown how TCA9534 will operate since the SCL frequency exceeds 400kHz.
    Is my thought correct?

    Q2.
    TCA9543A maximum SCL frequency is 400kHz. The customer want to access to TCAL9539 with 1MHz SCL.
    Do you have any 1MHz version of TCA9543A? 
    Also can TMUX136 be used for this requirement?

    Thank you again and best regards,
    Kazuya.

  • 0 in reply to Kazuya Nakai59
    TI__Mastermind 46928 points

    Hi Kazuya, 

    Kazuya Nakai59 said:
    Q1.
    I think you mean that this usage not recommended because it is unknown how TCA9534 will operate since the SCL frequency exceeds 400kHz.
    Is my thought correct?

    You are correct. 

    Kazuya Nakai59 said:
    Q2.
    TCA9543A maximum SCL frequency is 400kHz. The customer want to access to TCAL9539 with 1MHz SCL.
    Do you have any 1MHz version of TCA9543A? 
    Also can TMUX136 be used for this requirement?

    No 1 MHz version of TCA9543A. Highest frequency supported is 400kHz for all I2C switches. 

    TMUX136 can pass signals of high frequencies but this device is not controlled via the I2C bus. To change channels inside the TMUX136, you will need external GPIO's from the customers MCU. 

    Regards,

    Tyler