The PCA9848 is an ultra-low voltage, octal bidirectional translating switch controlled via
the I²C-bus. The SCL/SDA upstream pair fans out to eight downstream pairs, or channels.
Any or all SCx/SDx channels can be selected, determined by the programmable control
register. This feature allows multiple devices with the same I²C-bus address to reside on
the same bus. The switch device can also separate a heavily loaded I²C-bus into separate
bus segments, eliminating the need for a bus buffer.
An active LOW reset input allows the PCA9848 to recover from a situation where one of
the downstream I²C-buses is stuck in a LOW state. Pulling the RESET pin LOW resets
the I²C-bus state machine and deselects all the channels, as does the internal
Power-On Reset (POR) function.
The pass gates of the switches are constructed such that the VDD1 pin is used to limit the
maximum high voltage which is passed by the PCA9848. This allows the use of different
bus voltages on each channel, so that 0.8 V, 1.8 V, 2.5 V or 3.3 V parts can communicate
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 3.6 V tolerant.