Following a start condition, the bus master must output the address of the slave it is accessing. The address of the PCA9543A is shown in Figure 8-7. To conserve power, no internal pull-up resistors are incorporated on the hardware-selectable address pins and they must be pulled high or low.

Figure 8-7 Slave Address PCA9543A

The last bit of the slave address defines the operation to be performed. When set to a logic 1, a read is selected, while a logic 0 selects a write operation.