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PCA9554A: Address lines left open

Art Mecina
Genius 16595 points
Part Number: PCA9554A

Hello Guys,

Good day.

Our customer on their PCB design have left the address lines A0 to A2 open. The datasheet says it must be tied to Vcc or Gnd. What are the implications of leaving it open? Do they need to redo their design or simply tying this to ground or Vcc will fix the issue?

Do these lines have a defined state?

Thanks in advance!

Art

  • 0
    TI__Guru 60880 points

    Hi Art,

    Our I2C devices require the address pins to be referenced.

    "What are the implications of leaving it open?"

    If they are left floating, the device may not ACK to its address as the address could have floated to a different value.

    "Do they need to redo their design or simply tying this to ground or Vcc will fix the issue?"

    These pins need to be referenced to be reliably addressed. Tying to either GND/Vcc would work.

    "Do these lines have a defined state?"

    No. They are are defined by their reference bias.

    Thanks,

    -Bobby