General description
The PCA9555A is a low-voltage 16-bit General Purpose Input/Output (GPIO) expander with interrupt and weak pull-up resistors for I2C-bus/SMBus applications. NXP I/O expanders provide a simple solution when additional I/Os are needed while keeping interconnections to a minimum, for example, in ACPI power switches, sensors, push buttons, LEDs, fan control, etc.
In addition to providing a flexible set of GPIOs, the wide VDD range of 1.65 V to 5.5 V allows the PCA9555A to interface with next-generation microprocessors and microcontrollers where supply levels are dropping down to conserve power.
The PCA9555A contains the PCA9555 register set of four pairs of 8-bit Configuration, Input, Output, and Polarity Inversion registers.

FEATUREs and benefits
■ I2C-bus to parallel port expander
■ Operating power supply voltage range of 1.65 V to 5.5 V
■ Low standby current consumption:
   ♦ 1.5 A (typical at 5 V VDD)
   ♦ 1.0 A (typical at 3.3 V VDD)
■ Schmitt-trigger action allows slow input transition and better switching noise immunity at the SCL and SDA inputs
   ♦ Vhys = 0.10  VDD (typical)
■ 5 V tolerant I/Os
■ Open-drain active LOW interrupt output (INT)
■ 400 kHz Fast-mode I2C-bus
■ Internal power-on reset
■ Power-up with all channels configured as inputs with weak pull-up resistors
■ No glitch on power-up
■ Latched outputs with 25 mA drive maximum capability for directly driving LEDs
■ Latch-up performance exceeds 100 mA per JESD78, Class II
■ ESD protection exceeds JESD22
■ 2000 V Human Body Model (A114-A)
■ 1000 V Charged-Device Model (C101)
■ Packages offered: TSSOP24, HWQFN24