DESCRIPTION
The PCA9544A is a 1-of-4 bi-directional 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 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 will be 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
• 1-of-4 bi-directional translating multiplexer
• I2C 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 RdsON 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 stand-by current
• Operating power supply voltage range of 2.3 V to 5.5 V
• 5 V tolerant Inputs
• 0 to 400 kHz clock frequency
• ESD protection exceeds 2000 V HBM per JESD22-A114,
   200 V MM per JESD22-A115 and 1000 V per JESD22-C101
• Latchup testing is done to JESDEC Standard JESD78 which
   exceeds 100 mA
• Three packages offered: SO20, TSSOP20, and HVQFN20