PCA9539 16-bit I2C-bus And SMBus Low Power I/O Port With Interrupt And Reset

The PCA9539 is a 24-pin CMOS device that provide 16 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 I2C I/O expanders. I/O expanders provides a simple solution when additional I/O is needed for ACPI Power Switches Sensors pushbuttons, LEDs fans, etc. The PCA9539 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 All Registers CAN be read by the system master. The PCA9539 is identical to the PCA9555 except for the removal of the internal I/O pull-up resistor which greatly reduces power consumption when the I/Os are held LOW, repleacement of A2 with RESET and different address range. The PCA9539 open-drain interrupt 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. The power-on reset sets the Registers to their default values and initializes the device state machine. The RESET pin causes the same reset/sonfiguration to occur without depowering the device. Two hardware pins (A0, A1) vary the fixed I2C address and allow up to four devices to share the same I2C SMBus
By NXP Semiconductors