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SN74HC4066: SN74HC4066 multiplexing I2C signal to solve EEPROM I2C address conflict

na na78
Guru 16770 points
Part Number: SN74HC4066
Other Parts Discussed in Thread: TS3A24157, TCA9543A

Hi

Let me consider SN74HC4066 as use for I2C signal switching as follows.

What is the issue that would be supposed?

I believe we can offer the better solution if we use TS3A24157 as alternative.

However, we want to confirm whether the upper figure using SN74HC4066 has problems or not.

Could you tell me your view?

BestRegards

  • 0
    TI__Mastermind 45410 points

    Na Na,

    What are you trying to accomplish with this circuit?  The I2C bus has the ability to place multiple slave devices on the same I2C bus.  The I2C protocol has an address byte to select which slave device to select between so I don't know why you would need an 1:1 SPST switch like the SN74HC406  

    Here is a good app note Understanding the I2C bus I found in the I2C e2e forum that explains I2C addressing in more detail.

    If your slave devices have the same I2C address and you are trying to isolate them for proper communication I would recommend looking at this appnote that talks about how to solve this issue with devices like the TCA9543A.  

    How to select the correct I2C device

    Thank you,

    Adam

  • 0 in reply to Adam Torma
    Guru 16770 points
    Hi Adam

    Thank you for your reply.

    ROM is EEPROM for configuration of Timing Controller (master).
    These two EEPROMs can't be set different address, so placing them on the same I2C bus wouldn't be supported by the master device.

    We are trying to isolate SCL1/SDA1 and SCL2/SDA2 channels using SN74HC4066 device like the figure.

    I think this configuration might not be reasonable way, but this is the most inexpensive way that we could take.

    So if possible, could you please indicate issues and tell us why this configuration is not practical?

    BestRegards
  • 0 in reply to na na78
    TI__Mastermind 45410 points
    Na Na,

    I do not see an issue with the schematic you have above. If the SN74HC4066 device is the lowest cost solution for you it will isolate the I2C bus since the two EEPROMs can't be set different address.

    Adam