General description
The PCA9535 and PCA9535C are 24-pin CMOS devices that provide 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, 5 V I/O tolerance, lower supply current,
individual I/O configuration, and smaller packaging. I/O expanders provide a simple
solution when additional I/O is needed for ACPI power switches, sensors, push buttons,
LEDs, fans, etc.The PCA9535 and PCA9535C consist 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. Although pin-to-pin and I2C-bus address compatible with the PCF8575, software changes are required due to the enhancements and are discussed inApplication Note AN469.

FEATUREs
■ Operating power supply voltage range of 2.3 V to 5.5 V
■ 5 V tolerant I/Os
■ Polarity Inversion register
■ Active LOW interrupt output
■ Low standby current
■ Noise filter on SCL/SDA inputs
■ No glitch on power-up
■ Internal power-on reset
■ 16 I/O pins which default to 16 inputs
■ 0 Hz to 400 kHz clock frequency
■ ESD protection exceeds 2000 V HBM per JESD22-A114, 200 V MM per
   JESD22-A115, and 1000 V CDM per JESD22-C101
■ Latch-up testing is done to JEDEC Standard JESD78 which exceeds 100 mA
■ Offered in four different packages: SO24, TSSOP24, HVQFN24 and HWQFN24