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Regarding I2C interface using TCA9406

Ravikumar Rudraraju
Prodigy 10 points
Other Parts Discussed in Thread: TCA9406

Hi, 

My I2C connection schema is explained in detail in the attached pdf (2 page)

We have developed module 2 which works on 3.3V , the I2C on this device always operates in slave mode. We are interfacing this to other modules(modules 1 &3) which are working on 5V logic. Module 1 serves as I2C master.

Therefore we used TI TCA9406 for I2C voltage level conversion to interface the other modules to our module. I have pulled OE permanently and also connected the same pin to Micro GPIO on module 2

Refer to Page 1: The I2C connection schema is explained. In this configuration the I2C works perfectly OK. The problem is when we connect another device Module 3(refer page 2)

Refer to Page 2: I2C connection schema explained. In this mode the I2C doesn't communicate with the slave device on module 2. For isolating the problem, we have removed level translator on Module 2 and directly shorted the I2C bus of our module with the external I2C and it works perfectly fine. We have a doubt if the internal pull up resistors in this level translator device is creating problem?

Please review and suggest.

I2C Query.pdfRegards

Ravi

  • 0
    TI__Expert 5140 points

    Hi Ravi,

    Thanks for the question. It looks like the main cause of concern would actually come from the series resistance you have on SCL and SDA. My suggestion would be to remove or reduce these.

    Also, is there a specific reason for the 1Mohm pulldown resistors.

    Thanks,

    Siby