1 Features
1. 1-of-4 Bidirectional translating switches
. I2C bus and SMBus compatible
. Four active-low interrupt inputs
. Active-low interrupt output
. Active-low reset input
. Two address terminals, allowing up to four
devices on the I2C bus
. Channel selection via I2C bus, in any combination
. Power-up with all switch 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
1.65 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
. 4000-V Human-body model (A114-A)
. 1500-V Charged-device model (C101)

2 Applications
. Servers
. Routers (telecom switching equipment)
. Factory automation
. Products with I2C slave address conflicts (e.g.
multiple, identical temp sensors)

3 Description
The TCA9545A 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 (INT)
output acts as an AND of the four interrupt inputs.
An active-low reset (RESET) input allows the
TCA9545A 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 VCC terminal can be used to limit the
maximum high voltage, which will be passed by the
TCA9545A. 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 terminals are 5.5 V tolerant.