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PCA9543A: Host I2C to SMBus (2-channel) and Isolation

TI-CSC
Genius 13015 points
Part Number: PCA9543A
Other Parts Discussed in Thread: ISO1540, ISO1640

Hello E2E Experts,

Good day.

I have a design that will use two smart battery packs (SMBus)  I have looked at the PCA9543AD  to communicate with them from the I2C host. 

Do I also need to use an isolation device such as the ISO1540DR between the batteries and the PCA9543AD? There will be times when the battery is 

connected to the hardware but the hardware will not be on. 

Or, does Ti have a product that has both the ability to interface I2C and SMBUS and also isolate the battery bus from the host bus?

Thank you in advance for your support.

Regards,

CSC

  • 0
    Guru 317250 points

    When the switch is off, no current flows in either direction. (GND is shared.)

    You would need an isolator like the ISO1540 only for galvanic isolation.

  • 0
    TI__Guru 55815 points

    Hi CSC,

    Thanks for reaching out.

    The two battery packs and the host can communicate fine without isolation hence, isolation isn't a requirement from functionality point of view. Isolation is needed if customer wants to protect host from high voltage systems or EMI transients, they can also be used to separate the ground and reduce ground potential difference. It is the designer who should decide whether he wants these additional benefits.

    If customer does decide to use an isolated I2C device, then please recommend them the ISO1640 which is our latest I2C isolator device which also supports reinforced isolation. Let me know if you have any questions, thanks.


    Regards,
    Koteshwar Rao