The PCA9544A is a quad bidirectional translating switch controlled via the
I2C bus. The SCL/SDA upstream pair fans out to four downstream pairs, or
channels. One SCL/SDA pair can be selected at a time, and this is 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 puts the registers in their default state and initializes the
I2C state machine, with no channel selected.
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 PCA9544A. 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-V tolerant.
For all available packages, see the orderable addendum at the
end of the data sheet.
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