The CH423S I/O Expander SOP-28_300mil RoHS manufactured by Qin Heng is an integrated circuit that performs a specialized function. It is typically used to add more I/O ports to a logic circuit, microcontroller, or similar device. It consists of five ports, and each port can be individually configured to input or output signals, allowing for up to 40 additional I/O connections in a small space. The device has an integrated pull-up resistor, and is RoHS compliant for reliable performance in commercial applications. It operates from a single 3.3V or 5V supply, and can withstand up to 10V for short periods of time. The pins have a 300mil SOP package, and the device is typically used in industrial and automotive applications, as well as any other application that requires additional I/O connectivity.