PCF8574T/3,518 (NXP)

The PCF8574T/3,518 is a 8-bit remote I/O Expander for I?C-bus with interrupt. It provides general-purpose remote I/O expansion via the two-wire bidirectional I?C-bus (serial clock (SCL), serial data (SDA)). The devices consist of eight quasi-bidirectional ports, 100kHz I?C-bus interface, three hardware address inputs and interrupt output operating between 2.5 and 6V. The quasi-bidirectional port can be independently assigned as an input to monitor interrupt status or keypads or as an output to activate indicator devices such as LEDs. System master can read from the input port or write to the output port through a single register. The low current consumption of 2.5µA (typical, static) is great for mobile applications and the latched output ports directly drive LEDs. This is identical, except for the different fixed portion of the slave address.