The TCA9534A is a 16-pin device that provides 8
bits of general purpose parallel input and output (I/O) expansion for the two-line bidirectional
I2C bus (or SMBus) protocol. The device can operate with a power supply
voltage ranging from 1.65 V to 5.5 V, which allows for use with a wide range of devices. The device
supports both 100-kHz (Standard-mode) and 400-kHz (Fast-mode) clock frequencies. I/O expanders such
as the TCA9534A provide a simple solution when additional I/Os are needed for switches, sensors,
push-buttons, LEDs, fans, and other similar devices.
The features of the TCA9534A include an interrupt that is generated on the
INT pin. This allows the master to know when an input port changes state.
The A0, A1, and A2 hardware selectable address pins allow up to eight TCA9534A devices on the same
I2C bus. The device can also be reset to its default sate by cycling the
power supply and causing a power-on reset.