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 PCA9535 can remain a simple slave device.The device outputs (latched) have high-current drive capability for directly driving LEDs. The device has low current consumption.Although pin-to-pin and I2C address compatible with the PCF8575, software changes are required due to the enhancements.The PCA9535 is identical to the PCA9555, except for the removal of the internal I/O pullup resistor, which greatly reduces power consumption when the I/Os are held low.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 fixed I2C address of the PCA9535 is the same as the PCA9555, PCF8575, PCF8575C, and PCF8574, allowing up to eight of these devices in any combination to share the same I2C bus or SMBus.
