The PCF8574 can support I2C bus frequencies up to 400 kHz.
The PCF8574 can be reset by pulling the SCL line low for at least 2 clock cycles.
The PCF8574 can sink or source up to 25 mA of current per I/O pin.
Yes, the PCF8574 can be used as an input expander by configuring the I/O pins as inputs and reading their states through the I2C bus.
Each PCF8574 device can be assigned a unique address by connecting the A0, A1, and A2 pins to VCC or GND, allowing multiple devices to share the same I2C bus.