下载
1
SLVA787–September 2016
Submit Documentation Feedback
Copyright © 2016, Texas Instruments Incorporated
Choosing the Correct I
2
C Device for New Designs
Application Report
SLVA787–September 2016
Choosing the Correct I
2
C Device for New Designs
SibyJames
ABSTRACT
The I
2
C bus is a very popular and powerful bus used for communication between a single (or multiple)
master and a single (or multiple) slave device. In many applications there is a potential need for more
slave devices on the bus, isolation between similar addressed slaves, or a need for more I/Os. These
needs can be solved with an I
2
C buffer, switch, and I/O expander.
The application note helps users understand the use-cases of buffers and repeaters, switches, and I/O
expanders and how to select the appropriate device for an application.
Contents
1 Introduction ................................................................................................................... 2
2 I/O Expander Applications.................................................................................................. 3
2.1 RESET Pins ......................................................................................................... 4
2.2 Internal Pullups...................................................................................................... 4
2.3 Address Pins ........................................................................................................ 4
2.4 Level Shifting ....................................................................................................... 4
3 I
2
C Switches .................................................................................................................. 5
3.1 Control Register..................................................................................................... 7
3.2 Hot Insertion Supported............................................................................................ 7
3.3 Address Pins ........................................................................................................ 7
3.4 Level Shifting........................................................................................................ 7
4 I
2
C Buffers .................................................................................................................... 8
4.1 Pull-Up Resistors ................................................................................................... 9
5 I
2
C Voltage Translation .................................................................................................... 11
List of Figures
1 I
2
C Bus With Peripheral Devices Attached Example.................................................................... 2
2 Microcontroller or Processor Using I/O Expander to Control Peripherals............................................ 3
3 Selection Chart for TI I/O Expanders and their Key Features......................................................... 5
4 I
2
C bus with multiple slave devices with the same address............................................................ 6
5 Eight-Channel I
2
C Switch Example........................................................................................ 6
6 Selection Chart for TI I
2
C Switches and Their Key Features .......................................................... 8
7 Heavily-Loaded Bus Requiring I
2
C Buffer ................................................................................ 9
8 I
2
C bus utilizing I
2
C buffer, which allows more slave devices.......................................................... 9
9 Example of B-B side mismatch configuration for I
2
C buffers ........................................................ 10
10 Selection Chart for TI I/O Expanders and Their Key Features....................................................... 10
11 Operation of an I
2
C Voltage Translator/Level Shifter.................................................................. 11
