Overview: NCA9555B 16-bit I2C-bus I/O port
with interrupt
Datasheet (EN) 1.1 Product Overview
The NCA9555B is a 24-pin device that provides 16 bits of General Purpose parallel Input/Output (GPIO) expansion for the two-line bidirectional I2C bus applications. The device can operate with a power supply voltage (VDD) range from 1.65 V to 5.5 V. It provides a simple solution when additional I/Os are needed for ACPI power switches, sensors, push buttons, LEDs, fans, etc. The NCA9555B consists of two 8-bit Configuration (Input or Output selection); Input, Output and Polarity Inversion (active HIGH or active LOW operation) registers. The system master can enable the I/Os as either inputs or outputs by writing to the I/O configuration bits. The data for each Input or Output is kept in the corresponding Input or Output register. The polarity of the read register can be inverted with the Polarity Inversion register. All registers can be read by the system master. The NCA9555B open-drain interrupt 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. The power-on reset sets the registers to their default values and initializes the device state machine. Three hardware pins (A0, A1, A2) vary the fixed I2C-bus address and allow up to eight devices to share the same I2C-bus.
