PCA9556PW.112 is an interface-IO (Input/Output) expander manufactured by NXP. It is an octal SMBUS register interface with a 1-Wire open drain configurable I/O. The PCA9556PW.112 is an IO expander that can be used to interface a microcontroller with the external world, providing 8 configurable I/O lines. It can be used for a variety of applications, such as controlling relays, reading analog input signals, driving LED's or configuring a 1-Wire bus. The PCA9556PW.112 provides the capability to drive/sense a voltage up to 5.5V and is equipped with an on-chip temperature sensor allowing for automatic temperature compensation. It also features an open drain I/O pin and is able to control up to 8 low-power devices and accept up to 8 low-power inputs. The register interface allows up to 8 bytes of user data to be stored in non-volatile memory and an additional 8 bytes of data to be stored in the actual device's memory. The PCA9556PW.112 offers many features, such as low-power operation, direct register access, fast bit and byte I/O, and many more.