For the TCA9509 to function correctly, all devices on the A-side must be able to pull the A-side below the voltage input low contention level (V_ILC). This means that the V_OL of any device on the A-side must be below V_ILC min.

The V_OL can be adjusted by changing the I_OLthrough the device which is set by the pull-up resistance value. The pull-up resistance on the A-side must be carefully selected to ensure that the logic levels will be transferred correctly to the B-side.

Figure 8-2 Typical Star Application

Multiple B-sides of TCA9509 can be connected in a star configuration, allowing all nodes to communicate with each other. The A-sides should not be connected together when used in a star/parallel configuration.

Figure 8-3 Typical Series Application, Two B-Sides Connected Together

Figure 8-4 Typical Series Application, A-side Connected to B-Side

To further extend the I²C bus for long traces/cables, multiple TCA9509 devices can be connected in series as long as the A-side is connected to the B-side and V_CCA ≤ (V_CCB – 1 V) must also be met. Series connections can also be made by connecting both B-sides together while following power supply rule V_CCA ≤ (V_CCB – 1 V). I²C bus target devices can be connected to any of the bus segments. The number of devices that can be connected in series is limited by repeater delay/time-of-flight considerations on the maximum bus speed requirements.