General description
The PCA9544A is a 1-of-4 bidirectional translating multiplexer, controlled via the I2C-bus. The SCL/SDA upstream pair fans out to four SCx/SDx downstream pairs, or channels. Only one SCx/SDx channel is selected at a time, determined by the contents of the programmable control register. Four interrupt inputs, INT0 to INT3, one for each of the SCx/SDx downstream pairs, are provided. One interrupt output, INT, which acts as an AND of the four interrupt inputs, is provided.
A power-on reset function puts the registers in their default state and initializes the I2C-bus state machine with no channels selected.
The pass gates of the multiplexer are constructed such that the VDD pin can be used to limit the maximum high voltage which is passed by the PCA9544A. This allows the use of different bus voltages on each SCx/SDx 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.

Features and benefits
■ 1-of-4 bidirectional translating multiplexer
■ I2C-bus interface logic; compatible with SMBus
■ 4 active LOW interrupt inputs
■ Active LOW interrupt output
■ 3 address pins allowing up to 8 devices on the I2C-bus
■ Channel selection via I2C-bus
■ Power-up with all multiplexer channels deselected
■ Low Ron switches
■ Allows voltage level translation between 1.8 V, 2.5 V, 3.3 V and 5 V buses
■ No glitch on power-up
■ Supports hot insertion
■ Low standby current
■ Operating power supply voltage range of 2.3 V to 5.5 V
■ 5 V tolerant Inputs
■ 0 Hz to 400 kHz clock frequency
■ ESD protection exceeds 2000 V HBM per JESD22-A114 and 1000 V CDM per JESD22-C101
■ Latch-up testing is done to JEDEC Standard JESD78 which exceeds 100 mA
■ Three packages offered: SO20, TSSOP20 and HVQFN20