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TCA9509: TCA9509 / Connection of unused bus

S.Satoshi
Guru 21675 points
Part Number: TCA9509

Hi,

I understand that TCA9509 has SDA and SCL bus for I2C bus, but now my customer consider to use it other purpose and they need only one channel. Then can they leave open the unused bus or need to tie VCCx or GND?

Best Regards,

Satoshi / Japan Disty

  • 0
    TI__Intellectual 2885 points
    Hello Satoshi,

    If you only want to use one channel that is fine. I would recommend shorting the unused channel to ground, but it will also work if you leave it open.
  • 0
    TI__Genius 17195 points

    Hello Satoshi-san,

    What other purpose are they going to try?  I don't understand how they hope to communicate with the device by removing on either the SCLK or SDATA?  You need both signals to communicate.  Please give a more detailed explanation of what they are trying to do.

    -Francis Houde

  • 0 in reply to fhoude
    Guru 21675 points
    Hi Francis,

    My customer consider to use TCA9509 to translate HDMI DDC SDA/SCL signal. In addition they consider to use it for CEC signal to unionize the device. For CEC signal, only one channel is needed.

    Best Regards,
    Satoshi
  • 0 in reply to S.Satoshi
    TI__Genius 17195 points
    Hello Satoshi,
    Thanks for the clarification. One side of the unused channel should be either pulled to ground or to Vcc, but don't let both sides float. This could potentially cause excessive current draw. For example, if you want to use SCLA-SCLB channel to do the CEC signal than I would connect SDAA to ground and leave SDAB floating, simply because it is a short and convenient connection in the layout if using the DGK package.
    -Francis Houde