SLLSF93A June   2019  – January 2025 TUSB8042A

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Variants
    1. 4.1 Device Version Comparison
  6. 5 Pin Configuration and Functions
  7. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Timing Requirements
    7. 6.7 Timing Diagrams
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Battery Charging Features
      2. 7.3.2 USB Power Management
      3. 7.3.3 One-Time Programmable (OTP) Configuration
      4. 7.3.4 Clock Generation
      5. 7.3.5 Crystal Requirements
      6. 7.3.6 Input Clock Requirements
      7. 7.3.7 Power-Up and Reset
    4. 7.4 Device Functional Modes
      1. 7.4.1 External Configuration Interface
      2. 7.4.2 I2C EEPROM Operation
      3. 7.4.3 Port Configuration
      4. 7.4.4 SMBus Target Operation
  9. 8 Register Maps
    1. 8.1  Configuration Registers
    2. 8.2  ROM Signature Register
    3. 8.3  Vendor ID LSB Register
    4. 8.4  Vendor ID MSB Register
    5. 8.5  Product ID LSB Register
    6. 8.6  Product ID MSB Register
    7. 8.7  Device Configuration Register
    8. 8.8  Battery Charging Support Register
    9. 8.9  Device Removable Configuration Register
    10. 8.10 Port Used Configuration Register
    11. 8.11 Device Configuration Register 2
    12. 8.12 USB 2.0 Port Polarity Control Register
    13. 8.13 UUID Registers
    14. 8.14 Language ID LSB Register
    15. 8.15 Language ID MSB Register
    16. 8.16 Serial Number String Length Register
    17. 8.17 Manufacturer String Length Register
    18. 8.18 Product String Length Register
    19. 8.19 Device Configuration Register 3
    20. 8.20 USB 2.0 Only Port Register
    21. 8.21 Serial Number String Registers
    22. 8.22 Manufacturer String Registers
    23. 8.23 Product String Registers
    24. 8.24 Additional Feature Configuration Register
    25. 8.25 SMBus Device Status and Command Register
  10. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Discrete USB Hub Product
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
          1. 9.2.1.2.1 Upstream Port Implementation
          2. 9.2.1.2.2 Downstream Port 1 Implementation
          3. 9.2.1.2.3 Downstream Port 2 Implementation
          4. 9.2.1.2.4 Downstream Port 3 Implementation
          5. 9.2.1.2.5 Downstream Port 4 Implementation
          6. 9.2.1.2.6 VBUS Power Switch Implementation
          7. 9.2.1.2.7 Clock, Reset, and Misc
          8. 9.2.1.2.8 TUSB8042A Power Implementation
        3. 9.2.1.3 Application Curves
    3. 9.3 Power Supply Recommendations
      1. 9.3.1 TUSB8042A Power Supply
      2. 9.3.2 Downstream Port Power
      3. 9.3.3 Ground
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
        1. 9.4.1.1 Placement
        2. 9.4.1.2 Package Specific
        3. 9.4.1.3 Differential Pairs
      2. 9.4.2 Layout Examples
        1. 9.4.2.1 Upstream Port
        2. 9.4.2.2 Downstream Port
  11. 10Device and Documentation Support
    1. 10.1 Documentation Support
      1. 10.1.1 Related Documentation
    2. 10.2 Receiving Notification of Documentation Updates
    3. 10.3 Support Resources
    4. 10.4 Trademarks
    5. 10.5 Electrostatic Discharge Caution
    6. 10.6 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information

8.25 SMBus Device Status and Command Register

Figure 8-24 Register Offset F8h
Bit No.76543210
Reset State00000000
Table 8-25 Bit Descriptions – SMBus Device Status and Command Register
BitFieldTypeDescription
7:2RSVDROReserved. Read only, returns 0 when read.
1smbusRstRSUSMBus interface reset. This bit loads the registers back to the GRSTz values. Note, that since this bit can only be set when in SMBus mode the cfgActive bit is also reset to 1. When the software sets this bit, the software must reconfigure the registers as necessary.
This bit is set by writing a 1 and is cleared by hardware on completion of the reset. A write of 0 has no effect.
0cfgActiveRCUConfiguration active. This bit indicates that configuration of the TUSB8042A is currently active. The bit is set by hardware when the device enters the I2C or SMBus mode. The TUSB8042A shall not connect on the upstream port while this bit is 1.
When in I2C mode, the bit is cleared by hardware when the TUSB8042A exits the I2C mode.
When in the SMBus mode, this bit must be cleared by the SMBus host to exit the configuration mode and allow the upstream port to connect.
The bit is cleared by a writing 1. A write of 0 has no effect.