Texas Instruments PCA9554 Remote 8-Bit I2C and SMBus I/O Expander with Interrupt Output and Configuration Registers PCA9554DB

The PCA9554 is an 8-bit I2C and SMBus I/O expander designed for operation within a power supply voltage range of 2.3 V to 5.5 V. It features an open-drain active-low interrupt output, allowing it to signal changes in input states to a microcontroller without continuous communication over the I2C bus. The device supports a 400-kHz fast I2C bus and can accommodate up to eight devices on the same bus through three hardware address pins. The PCA9554 includes configuration registers for input/output selection and a polarity inversion register, enabling flexible control of the I/O pins. At power-up, all channels are configured as inputs with weak pull-ups to VCC, and the device includes an internal power-on reset feature to ensure proper initialization. The outputs are latched and capable of driving high-current loads, such as LEDs. This part is compatible with the PCF8574 in terms of pin configuration and I2C addressing, although software modifications may be necessary due to the PCA9554's enhanced features. The device is available in various packages, including SSOP and TSSOP, and operates within a temperature range of -40¬8C to 85¬8C.