The PCA9539APW,118 is a 16-bit Input/output (GPIO) Expander with interrupt and reset for I²C-bus/SMBus applications. The NXP I/O expander provides a simple solution when additional I/Os are needed while keeping interconnections to a minimum. In addition to providing a flexible set of GPIOs, the wide VDD range of 1.65 to 5.5V allows the PCA9539A to interface with next-generation microprocessors and microcontrollers where supply levels are dropping down to conserve power. It contains the PCA9539 register set of four pairs of 8-bit configuration, input, output and polarity inversion registers. The expander is a pin-to-pin replacement to the PCA9539 and other industry-standard part numbers. A more fully featured part, it is also available with Agile I/O features. The expander open-drain interrupt (INT) output is activated when any input state differs from its corresponding Input Port register state and is used to indicate to the system master that an input state has changed.