SLVA787 September   2016 LM8330 , LM8335 , P82B715 , P82B96 , PCA9306 , PCA9306-Q1 , PCA9515A , PCA9515B , PCA9518 , PCA9534 , PCA9534A , PCA9535 , PCA9536 , PCA9538 , PCA9539 , PCA9543A , PCA9544A , PCA9545A , PCA9546A , PCA9548A , PCA9554 , PCA9554A , PCA9555 , PCA9557 , PCF8574 , PCF8574A , PCF8575 , PCF8575C , TCA4311A , TCA6408A , TCA6416A , TCA6418E , TCA6424A , TCA9509 , TCA9517 , TCA9517A , TCA9534 , TCA9534A , TCA9535 , TCA9538 , TCA9539 , TCA9539-Q1 , TCA9543A , TCA9544A , TCA9545A , TCA9546A , TCA9548A , TCA9554 , TCA9554A , TCA9555 , TCA9617A , TCA9617B , TCA9800 , TCA9801 , TCA9802 , TCA9803

 

  1.   Choosing the Correct I2C Device for New Designs
    1.     Trademarks
    2. 1 Introduction
    3. 2 I/O Expander Applications
      1. 2.1 RESET Pins
      2. 2.2 Internal Pullups
      3. 2.3 Address Pins
      4. 2.4 Level Shifting
    4. 3 I2C Switches
      1. 3.1 Control Register
      2. 3.2 Hot Insertion Supported
      3. 3.3 Address Pins
      4. 3.4 Level Shifting
    5. 4 I2C Buffers
      1. 4.1 Pull-Up Resistors
        1. 4.1.1 Static Voltage Offset
        2. 4.1.2 Level Shifting
    6. 5 I2C Voltage Translation

3.1 Control Register

I2C switches determine which channels are connected internally through their control register. Following the successful acknowledgement of the address byte, the bus master sends a command byte that is stored in the control register of the I2C switch. This register can be written and read via the I2C bus. Each bit in the command byte corresponds to an SCn or SDn (SCn/SDn) channel and a high (or 1) selects this channel. Multiple SCn/SDn channels may be selected at the same time. When a channel is selected, the channel becomes active after a stop condition has been placed on the I2C bus. This ensures that all SCn/SDn lines are in a high state when the channel is made active, so that no false conditions are generated at the time of connection. A stop condition always must occur immediately after the acknowledge cycle. If multiple bytes are received by the I2C switch, it saves the last byte received