PCA9546A

• 1-of-4 Bidirectional Translating Switches
• I²C Bus and SMBus Compatible
• Active-Low Reset Input
• Three Address Pins, Allowing up to Eight
  PCA9546A Devices on the I²C Bus
• Channel Selection Via I²C Bus, in Any
  Combination
• Power-up With All Switch Channels Deselected
• Low R_ON 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
• 5.5 V Tolerant Inputs
• 0 to 400-kHz Clock Frequency
• Latch-Up Performance Exceeds 100 mA Per
  JESD 78
• ESD Protection Exceeds JESD 22
  • 2000-V Human-Body Model (A114-A)
  • 1000-V Charged-Device Model (C101)

The PCA9546A 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 PCA9546A 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 function.

The pass gates of the switches are constructed such that the V_CC pin can be used to limit the maximum high voltage, which will be passed by the PCA9546A. 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.