The PCA9543A is a dual bidirectional translating switch controlled by the I2C bus. The SCL/SDA upstream pair fans out to two downstream pairs, or channels. Either individual SCn/SDn channel or both channels can be selected, determined by the contents of the programmable control register. Two interrupt inputs (INT1–INT0), one for each of the downstream pairs, are provided. One interrupt output (INT) acts as an AND of the two interrupt inputs.

An active-low reset (RESET) input allows the PCA9543A to recover from a situation where one of the downstream I2C buses is stuck in a low state. PullingRESETlow resets the I2C state machine and causes both of the channels to be deselected, as does the internal power-on reset function.

The pass gates of the switches are constructed such that the VCC pin can be used to limit the maximum high voltage, which will be passed by the PCA9543A. This allows the use of different bus voltages on each pair, so that 1.8-V, 2.5-V, or 3.3-V parts can communicate with 5-V parts without any additional protection. External pull-up resistors pull the bus up to the desired voltage level for each channel. All I/O pins are 5.5-V tolerant.Read more