2-channel 2.3- to 5.5-V I2C/SMBus switch with interrupt, reset & voltage translation

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.

Pulling RESET low 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.