SCPS193D July   2010  – January 2023 TCA6424A

PRODUCTION DATA  

  1. 1 Features
  2. 2 Description
  3. 3 Revision History
  4. 4 Description (continued)
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings (1)
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 I2C Interface Timing Requirements
    7. 6.7 Reset Timing Requirements
    8. 6.8 Switching Characteristics
    9. 6.9 Typical Characteristics
  7. 7 Parameter Measurement Information
  8. 8 Detailed Description
    1. 8.1 Overview
      1. 8.1.1 Voltage Translation
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 I/O Port
      2. 8.3.2 I2C Interface
    4. 8.4 Device Functional Modes
      1. 8.4.1 Device Address
    5. 8.5 Programming
      1. 8.5.1 Power-On Reset
      2. 8.5.2 Reset Input ( RESET)
      3. 8.5.3 Interrupt Output ( INT)
      4. 8.5.4 Bus Transactions
        1. 8.5.4.1 Writes
        2. 8.5.4.2 Reads
    6. 8.6 Register Maps
      1. 8.6.1 Control Register and Command Byte
      2. 8.6.2 Register Descriptions
  9. 9 Application and Implementation
    1. 9.1 Typical Application
      1. 9.1.1 Detailed Design Procedure
        1. 9.1.1.1 Minimizing ICC When I/Os Control LEDs
    2. 9.2 Power Supply Recommendation
  10. 10Device and Documentation Support
    1. 10.1 Receiving Notification of Documentation Updates
    2. 10.2 Support Resources
    3. 10.3 Trademarks
    4. 10.4 Electrostatic Discharge Caution
    5. 10.5 Glossary
      1.      Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

8.5.4.2 Reads

The bus controller first must send the TCA6424A address with the LSB set to a logic 0 (see Figure 8-6 for device address). The command byte is sent after the address and determines which register is accessed.

After a restart, the device address is sent again but, this time, the LSB is set to a logic 1. Data from the register defined by the command byte then is sent by the TCA6424A (see Figure 8-9 and Figure 8-10).

After a restart, the value of the register defined by the command byte matches the register being accessed when the restart occurred. For example, if the command byte references Input Port 1 before the restart, and the restart occurs when Input Port 0 is being read, the stored command byte changes to reference Input Port 0. The original command byte is forgotten. If a subsequent restart occurs, Input Port 0 is read first. Data is clocked into the register on the rising edge of the ACK clock pulse. After the first byte is read, additional bytes may be read, but the data now reflects the information in the other register in the pair. For example, if Input Port 1 is read, the next byte read is Input Port 0.

Data is clocked into the register on the rising edge of the ACK clock pulse. There is no limitation on the number of data bytes received in one read transmission, but when the final byte is received, the bus controller must not acknowledge the data.

Figure 8-9 Read From Register

A. Transfer of data can be stopped at any time by a Stop condition. When this occurs, data present at the latest acknowledge phase is valid (output mode). It is assumed that the command byte previously has been set to 00 (read Input Port register).
B. This figure eliminates the command byte transfer, a restart, and target address call between the initial target address call and actual data transfer from P port (see Figure 8-9).
C. Auto-increment mode is enabled.
Figure 8-10 Read Input Port Register