PCA9537

   The PCA9537 is a 10-pin CMOS device that provide 4 bits of General Purpose parallel Input/Output (GPIO) expansion with interrupt and reset for I²C/SMBus applications and was developed to enhance the Philips family of IC I/O expanders. I/O expanders of PCA9537 provides a simple solution when additional I/O is needed for ACPI power switches, sensors, pushbuttons, LEDs, fans, etc.

   The PCA9537 consists of a 4-bit Configuration register (Input or Output selection); 4-bit Input register, 4-bit Output register and a 4-bit Polarity inversion register (Active-HIGH or Active-LOW operation). The system master of PCA9537 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 of PCA9537 is kept in the corresponding Input or Output register. The polarity of the input port register can be inverted with the Polarity Inversion Register. All registers can be read by the system master.