PCA9535
is a GPIO expander with 16 IO lines which has I2C bus interface.
It provides additional IOs for I2C bus master such as SBC or MCU that can be used to read push button or sensor, to control LED, etc.
PCA9555 is identical to PCA9535 except the presence of internal pull-up resistor
which increases power consumption when the IOs are low.
PCA9535C is another variation of PCA9535 with open drain outputs.
Its operating supply voltage range is 2.3V to 5.5V.
There are 3 hardware pins which allow to use 8 different I2C bus addresses, from 0x20 to 0x27.
