Data Sheet

Copyright © 2016, Texas Instruments Incorporated
Input Filter I
2
C Bus Control
Power-On
Reset
Switch Control Logic
PCA9546A
15
14
8
16
3
5
7
10
12
4
6
9
11
A0
A1
A2
1
2
13
SDA
SCL
V
CC
RESET
GND
SC0
SC1
SC2
SC3
SD0
SD1
SD2
SD3
10
PCA9546A
SCPS148G –OCTOBER 2005–REVISED MAY 2016 www.ti.com
Product Folder Links: PCA9546A
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8 Detailed Description
8.1 Overview
The PCA9546A is a 4-channel, bidirectional translating I
2
C switch. The master SCL/SDA signal pair is directed to
four channels of slave devices, SC0/SD0-SC3/SD3. Any individual downstream channel can be selected as well
as any combination of the four channels.
The device offers an active-low RESET input which resets the state machine and allows the PCA9546A to
recover should one of the downstream I
2
C buses get stuck in a low state. The state machine of the device can
also be reset by cycling the power supply, V
CC
, also known as a power-on reset (POR). Both the RESET function
and a POR will cause all channels to be deselected.
The connections of the I
2
C data path are controlled by the same I
2
C master device that is switched to
communicate with multiple I
2
C slaves. After the successful acknowledgment of the slave address (hardware
selectable by A0 and A1 pins), a single 8-bit control register is written to or read from to determine the selected
channels.
The PCA9546A 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