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TCA9543A: Question regarding TCA9543A I2C configuration

Joel Brantley
Prodigy 10 points

Part Number: TCA9543A

In a configuration where you are using multiple master devices with each master device having an I2C connection to a single TCA9543APWR that is connected to a common shared I2C bus. If each TCA9543APWR had the same I2C address pin selection, could a master device reconfigure the switch connections of another TCA9543APWR, or can the switch "outputs" (SC0,SD0,SC1,SD1) only be configured through SCL/SDA on the "input" side? I want to make sure SoC 1 couldn't reconfigure the TCA9543 of SoC 2 if they share an address and therefore the messages would go to both devices.

Our primary concern is that once all SoCs come up and configure the switches, if all are configured on the same bus (SC0/SD0 for instance) would the I2C messages be messed up due to all switches sharing the same I2C address?

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  • 0
    TI__Genius 10770 points

    Hi Joel,


    Yes, one master device will accidentally reconfigure the other switches if they share the same I2C address. When a channel on the TCA9543A is enabled,  the bidirectional electrical connection between the downstream shared bus (SCx/SDx) and the switch's main input pins (SCL/SDA). If multiple SoCs connect to the same shared bus, an I2C command sent by SoC 1 will propagate "backward" from that shared bus through the active channels of any other connected switches. Because all the switches share the exact same I2C address, the internal control logic of every active switch will see the command, acknowledge it, and update its registers simultaneously. To prevent this cross-configuration, you must use the A0 and A1 pins to ensure each TCA9543A is assigned a unique hardware I2C address.

    Thank you,

    Arya