Applications of the TCA6416A will have this device connected as a target to an I2C controller (processor), and the I2C bus may contain any number of other target devices. The TCA6416A will be in a remote location from the controller, placed close to the GPIOs to which the controller needs to monitor or control.

A typical application of the TCA6416A will operate with a lower voltage on the controller side (VCCI), and a higher voltage on the P-port side (VCCP). The P-ports can be configured as outputs connected to inputs of devices such as enable, reset, power select, the gate of a switch, and LEDs. The P-ports can also be configured as inputs to receive data from interrupts, alarms, status outputs, or push buttons.