The PCAL6524 is a 24-bit general purpose I/O expander that provides remote I/O expansion for most
microcontroller families via the Fast-mode Plus (Fm+) I2C-bus interface. The ultra low-voltage
interface allows for direct connection to a microcontroller operating down to 0.8 V. NXP I/O
expanders provide a simple solution when additional I/Os are needed while keeping interconnections
to a minimum, for example, in battery-powered mobile applications for interfacing to sensors, push
buttons, keypad, etc.
In addition to providing a flexible set of GPIOs, it simplifies interconnection of a processor
running at one voltage level down to 0.8 V to I/O devices operating at a different voltage level
1.65 V to 5.5 V.