The I²C interface runs at 100 kHz standard mode, and the part includes an interrupt output that signals the host when an input changes — useful for keypads or sensor monitoring where you want to avoid polling. The 20-TSSOP package (4.40 mm wide) is a surface-mount footprint common in space-constrained PCBs.
1 mA source, 25 mA sink — the drive asymmetry matters
The output stage can sink 25 mA per pin but source only 1 mA. For loads that need sourcing current (relay coils, small solenoids), you will want a transistor or MOSFET buffer. The strong sink is fine for driving open-drain buses or pulling down a line.
Industrial temperature range — not for under-hood
It is not qualified for automotive under-hood environments (125°C ambient) — if the design needs that, look at the AEC-Q100 graded PCF8574-Q1 variant.