8.1 Overview

The TCA9544A is a 4-channel, bidirectional translating I2C Muliplexer. The master SCL/SDA signal pair is directed to one of the four channels of slave devices, SC0/SD0-SC3/SD3. Four interrupt inputs (INT3–INT0), one for each of the downstream pairs, are provided. One interrupt output (INT) acts as an AND of the four interrupt inputs.

The device can be reset by cycling the power supply, V_CC, also known as a power-on reset (POR), which resets the state machine and allows the TCA9544A to recover should one of the downstream I²C buses get stuck in a low state. A POR event will cause all channels to be deselected.

The connections of the I²C data path are controlled by the same I²C master device that is switched to communicate with multiple I²C slaves. After the successful acknowledgment of the slave address (hardware selectable by A0-A2 pins), a single 8-bit control register is written to or read from to determine the selected channels and state of the interrupts.

The TCA9544A may also be used for voltage translation, allowing the use of different bus voltages on each SCn/SDn pair such that 1.8-V, 2.5-V, or 3.3-V parts can communicate with 5-V parts. This is achieved by using external pull-up resistors to pull the bus up to the desired voltage for the master and each slave channel.