The PCA9847 is an ultra-low voltage, octal bidirectional translating multiplexer controlled viathe I2C-bus. The SCL/SDA upstream pair fans out to eight downstream pairs, orchannels. Any single SCx/SDx channel can be selected, determined by the programmablecontrol register. This feature allows multiple devices with the same I2C-busaddress to reside on the same bus. The multiplexer device can also separate a heavilyloaded I2C-bus into separate bus segments, eliminating the need for a busbuffer.

An active LOW reset input allows the PCA9847 to recover from a situation where one of thedownstream I2C-buses is stuck in a LOW state. Pulling the RESET pin LOW resets the I2C-bus state machineand deselects all the channels, as does the internal Power-On Reset (POR) function.

The pass gates of the multiplexers are constructed such that the VDD1 pin isused to limit the maximum high voltage which is passed by the PCA9847. This allows theuse of different bus voltages on each channel, so that 0.8 V, 1.8 V, 2.5 V or 3.3 Vparts can communicate without any additional protection. External pull-up resistors pullthe bus up to the desired voltage level for each channel. All I/O pins are 3.6 Vtolerant.