I/O Expander, 16 bit, I2C, SMBus, 2.3V, 5.5V, TSSOP, 24 Pins - 

The PCA9555PW,112 is a 24-pin CMOS Device that provides 16 bits of general purpose parallel input/output (GPIO) expansion for I²C-bus/SMBus applications and was developed to enhance the NXP semiconductors family of I²C-bus I/O expanders. The improvements include higher drive capability, 5V I/O tolerance, lower supply current and individual I/O configuration. I/O expanders provide a simple solution when additional I/O is needed for ACPI power switches, push buttons, LEDs and fans. The PCA9555 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.