The PC8574�is an 8-bit input/output (I/O) expander for the two-line bidirectional bus (I2C) designed for 2.5-V to 6-V VCC operation.
The PCF8574 device provides general-purpose remote I/O expansion for most microcontroller families by way of the I2C interface [serial clock (SCL), serial data (SDA)].
The device features an 8-bit quasi-bidirectional I/O port (P0–P7), including latched outputs with high current drive capability for directly driving LEDs. Each quasi-bidirectional I/O can be used as an input or output without the use of a data-direction control signal. At power-on, the I/Os are high. In this mode, only a current source to VCC is active
This device has a wide input voltage range and it can operate in a range of between 2.5V to 7V, the input current range is 20mA and the continuous output current is 4mA and this device can operate in between the range of 150*C. This device has support for both high speed and low-speed SPI that means this device can operate at 100KHz
