The TCA9546A is a quad bidirectional translating switch controlled via the
I2C bus. The SCL/SDA upstream pair fans out to four downstream pairs, or
channels. Any individual SCn/SDn channel or combination of channels can be selected, determined by
the contents of the programmable control register.
An active-low reset (RESET) input allows the TCA9546A to recover
from a situation in which one of the downstream I2C buses is stuck in a
low state. Pulling RESET low resets the I2C state
machine and causes all the channels to be deselected, as does the internal power-on reset
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 TCA9546A. 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.
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