The Texas Instruments TCA9555 is a low-voltage 16-bit I2C and SMBus I/O expander tailored for operation in the 1.65-V to 5.5-V range, making it an ideal candidate for enhancing the I/O capabilities of general-purpose microcontrollers with limited GPIOs. Given part numbers corresponding to different package types, such as TCA9555DBR, TCA9555DBT for SSOP packages, TCA9555PWR for TSSOP packages, and TCA9555RGER, TCA9555RTWR for VQFN and WQFN packages respectively, the TCA9555 provides versatility in integration across various design layouts. This component features an open-drain active-low interrupt output, configurable slave addresses utilizing 3 address pins, and polarity inversion registers. Notably, this I/O expander exceeds the 100 mA per JESD 78, Class II latch-up performance and offers significant ESD protection. These characteristics, combined with the capability to directly drive LEDs with its latched outputs, make the TCA9555 a practical solution for applications requiring additional I/Os such as in servers, personal electronics, and industrial automation equipment, among others.