PCA9554ARGTR

The PCA9554A 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. INT can be connected to the interrupt input of a microcontroller. By sending an interrupt signal on this line, the remote I/O can inform the microcontroller if there is incoming data on its ports without having to communicate via the I2C bus. Thus, the PCA9554A can remain a simple slave device.The device’s outputs (latched) have high-current drive capability for directly driving LEDs and low current consumption.Three hardware pins (A0, A1, and A2) are used to program and vary the fixed I2C address and allow up to eight devices to share the same I2C bus or SMBus.The PCA9554A is pin-to-pin and I2C address compatible with the PCF8574A. However, software changes are required, due to the enhancements in the PCA9554A over the PCF8574A.The PCA9554A and PCA9554 are identical except for their fixed I2C address. This allows for up to 16 of these devices (8 of each) on the same I2C/SMBus.