The TCA6416A is a 16-bit I/O expander for the two-line bidirectional bus (I²C) is designed for 1.65-V to 5.5-V operation. It provides general-purpose remote I/O expansion and bidirectional voltage translation for processors through I²C communication, an interface consisting of serial clock (SCL), and serial data (SDA) signals.

The major benefit of the TCA6416A is its voltage translation capability over a of a wide supply voltage range. This allows the TCA6416A 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 5-V power supply.

The VCCI pin is the power supply for the I²C bus, and therefore the pull-up resistors connected to the SCL, SDA, INT, and RESET pins should be terminated at V_CCI on the opposite side. level of the I²C bus to the TCA6416A. The VCCP pin is the power supply for the P-ports and if pull-up resistors are used on any P-port or LEDs are driven by any P-port, then the resistor(s) or LED(s) connected to P00-P07 and P10-P17 should be terminated at V_CCP on the opposite side. The device P-ports configured as outputs have the ability to sink up to 25 mA for directly driving LEDs, but the current must be limited externally with an additional resistance.

The features of the device include an interrupt that is generated on the INT pin whenever an input port changes state. The devices can also be reset to its default state by applying a low logic level to the RESET pin or by cycling power to the device and causing a power-on reset. The ADDR hardware selectable address pin allows two TCA6416A devices to be connected to the same I²C bus.

The TCA6416A 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 TCA6416A can inform the processor if there is incoming data on the remote I/O ports without having to communicate via the I²C bus. Thus, the TCA6416A can remain a simple target device.

The system controller can reset the TCA6416A in the event of a timeout or other improper operation by asserting a low on the RESET input pin or by cycling the power to the VCCP pin and causing a power-on reset (POR). A reset puts the registers in their default state and initializes the I²C /SMBus state machine. The RESET feature and a POR cause the same reset/initialization to occur, but the RESET feature does so without powering down the part.

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.

The TCA6416A's digital core consists of eight 8-bit data registers: two Configuration registers (input or output selection), two Input Port registers, two Output Port registers, and two Polarity Inversion registers. At power on or after a reset, 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. All registers can be read by the system controller.