INT

A0

A1

TCA9543A

RESET

SC1

6

10

5

9

7

14

3

13

12

2

11

SC0

SD0

SD1

GND

VCC

SCL

SDA

INT1

INT0

Input Filter

Output Filter

I C Bus

Control

2

Interrupt Logic

Switch Control Logic

Power-On

Reset

4

8

1

11

TCA9543A

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SCPS206B – MARCH 2014 – REVISED NOVEMBER 2019

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8 Detailed Description

8.1 Overview

The TCA9543A is a 2-channel, bidirectional translating I2C switch. The master SCL/SDA signal pair is directed to

two channels of slave devices, SC0/SD0-SC1/SD1. Either individual downstream channel can be selected as

well as both channels. The TCA9543A also supports interrupt signals in order for the master to detect an

interrupt on the INT output terminal that can result from any of the slave devices connected to the INT1-INT0

input terminals.

The device offers an active-low RESET input which resets the state machine and allows the TCA9543A to

recover should one of the downstream I2C buses get stuck in a low state. The state machine of the device can

also be reset by cycling the power supply, VCC, also known as a power-on reset (POR). Either using the RESET

function or causing a POR will cause both channels to be deselected.

The connections of the I2C data path are controlled by the same I2C master device that is switched to

communicate with multiple I2C slaves. After the successful acknowledgment of the slave address (hardware

selectable by A0 and A1 terminals), a single 8-bit control register is written to or read from to determine the

selected channels and state of the interrupts.

The TCA9543A may also be used for voltage translation, allowing the use of different bus voltages on each

SCn/SDn pair such that 1.8-V, 2.5-V, or 3.3-V parts can communicate with 5-V parts. This is achieved by using

external pull-up resistors to pull the bus up to the desired voltage for the master and each slave channel.

8.2 Functional Block Diagram