The TCAL6416R supports voltage translation over a wide supply voltage range. This allows the device to interface with modern processors on the I²C side, where supply levels are lower to conserve power. In contrast to the dropping power supplies of processors, some PCB components (such as LEDs) still require a higher voltage power supply.

The V_CCI pin is the power supply for the I²C bus, and therefore the pull-up resistors connected to the SCL, SDA, and RESET pins should be terminated at V_CCI. The INT output has an open-drain structure and requires an external pull-up resistor to V_CCP or V_CCI depending on the application. The V_CCP pin is the power supply for the P-ports. If the external pull-up resistors are used on any P-port, or if the LEDs are driven by any P-port, then the one or more of the resistors or LEDs connected to P00-P07 and P10-P17 should be terminated at V_CCP. The device P-ports configured as outputs have the ability to sink up to 25mA for directly driving LEDs, but the current must be limited externally with an additional resistance.

The TCAL6416R digital core consists of 8-bit data registers, which allow the user to configure the I/O port characteristics. At power-up or after a software reset call, the I/Os are configured as inputs. However, the system controller can configure the I/Os as either inputs or outputs by writing to the Configuration registers. The data for each input or output is kept in the corresponding Input Port or Output Port register. The polarity of the Input Port register can be inverted with the Polarity Inversion register. The system controller can read all registers. Additionally, the TCAL6416R has Agile I/O functionality, which is specifically targeted to enhance the I/O ports. The Agile I/O features and registers include programmable output drive strength, programmable pull-up and pull-down resistors, latchable inputs, maskable interrupts, interrupt status register, and programmable open-drain or push-pull outputs. These configuration registers improve the I/O by increasing flexibility and allowing the user to optimize their design for power consumption, speed, and EMI.

Other features of the device include an interrupt that is generated on the INT pin whenever an input port changes state. The device can be reset to its default state by issuing a software reset command or by cycling power to the device and causing a power-on reset. The ADDR hardware selectable address pin allows two TCAL6416R devices to be connected to the same I²C bus.

The TCAL6416R open-drain interrupt (INT) output is activated when any input state differs from its corresponding Input Port register state and is used to indicate to the system controller that an input state has changed. The INT pin can be connected to the interrupt input of a processor. By sending an interrupt signal on this line, the device can inform the processor if there is incoming data on the remote I/O ports without having to communicate through the I²C bus. Thus, the device can remain a simple target device.

The system controller can re-initialize I²C/SMBus state machine in the event of a timeout or other improper operation by asserting a low on the RESET input pin without resetting the sticky registers to default values.

One hardware pin (ADDR) can be used to program and vary the fixed I²C address, and allow two devices to share the same I²C bus or SMBus.