The TCA6408A is a 16-pin device that provides 8-bits of general purpose parallel input/output (I/O) expansion for the two-line bidirectional I2C bus (or SMBus) protocol. This device can operate with a power supply voltage ranging from 1.65 V to 5.5 V on both the I2C bus side (VCCI) and on the P-port side (VCCP). This allows the TCA6408A to interface with next-generation microprocessors and microcontrollers on the SDA/SCL side, where supply levels are dropping down to conserve power. In contrast to the dropping power supplies of microprocessors and microcontrollers, some PCB components such as LEDs remain at a 5-V power supply.