The PCA9548A has eight bidirectional translating switches that can be controlled via the
I2C bus. The SCL/SDA upstream pair fans out to eight downstream pairs,
or channels. Any individual SCx/SDx channel or combination of channels can be selected, determined
by the contents of the programmable control register.
The system master can reset the PCA9548A in the event of a timeout or other improper
operation by asserting a low in the RESET input. Similarly, the power-on
reset deselects all channels and initializes the I2C/SMBus state
machine. Asserting RESET causes the same reset/initialization to occur
without powering down the part.
The pass gates of the switches are constructed so that the VCC pin
can be used to limit the maximum high voltage, which is passed by the PCA9548A. This allows the use
of different bus voltages on each pair, so that 1.8-V or 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-V tolerant.
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