The TCA9544A 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. Four interrupt inputs
(INT3–INT0), one for each of the downstream pairs,
are provided. One interrupt output (INT) acts as an AND of the four
A power-on reset function returns the registers to their default state and initializes
the I2C state machine, with all channels deselected.
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 TCA9544A. 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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