SLUSBX9I March   2014  – July 2019 TPS23861

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified Schematic
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin Functions
  6. 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 Switching Characteristics
    8. 6.8 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
      1. 7.1.1 Detailed Pin Description
      2. 7.1.2 I2C Detailed Pin Description
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Detection Resistance Measurement
      2. 7.3.2  Physical Layer Classification
      3. 7.3.3  Class and Detect Fields
      4. 7.3.4  Register State Following a Fault
      5. 7.3.5  Disconnect
      6. 7.3.6  Disconnect Threshold
      7. 7.3.7  Fast Shutdown Mode
      8. 7.3.8  Legacy Device Detection
      9. 7.3.9  VPWR Undervoltage and UVLO Events
      10. 7.3.10 Timer-Deferrable Interrupt Support
      11. 7.3.11 A/D Converter and I2C Interface
      12. 7.3.12 Independent Operation when the AUTO Bit is Set
      13. 7.3.13 I2C Slave Address and AUTO Bit Programming
    4. 7.4 Device Functional Modes
      1. 7.4.1 Off
      2. 7.4.2 Manual
      3. 7.4.3 Semi-Auto
      4. 7.4.4 Auto
      5. 7.4.5 Push-Button Power On Response
      6. 7.4.6 TSTART Indicators of Detect and Class Failures
      7. 7.4.7 Device Power On Initialization
    5. 7.5 Register Map – I2C-Addressable
      1. 7.5.1  Interrupt Register
      2. 7.5.2  Interrupt Enable Register
      3. 7.5.3  Power Event Register
      4. 7.5.4  Detection Event Register
      5. 7.5.5  Fault Event Register
      6. 7.5.6  Start/ILIM Event Register
      7. 7.5.7  Supply Event Register
      8. 7.5.8  Port n Status Register
        1. 7.5.8.1 Port 1 Status Register
        2. 7.5.8.2 Port 2 Status Register
        3. 7.5.8.3 Port 3 Status Register
        4. 7.5.8.4 Port 4 Status Register
      9. 7.5.9  Power Status Register
      10. 7.5.10 I2C Slave Address Register
      11. 7.5.11 Operating Mode Register
      12. 7.5.12 Disconnect Enable Register
      13. 7.5.13 Detect/Class Enable Register
      14. 7.5.14 Port Power Priority Register
      15. 7.5.15 Timing Configuration Register
      16. 7.5.16 General Mask 1 Register
      17. 7.5.17 Detect/Class Restart Register
      18. 7.5.18 Power Enable Register
      19. 7.5.19 Reset Register
      20. 7.5.20 Legacy Detect Mode Register
      21. 7.5.21 Two-Event Classification Register
      22. 7.5.22 Interrupt Timer Register
      23. 7.5.23 Disconnect Threshold Register
        1. 7.5.23.1 Bits Description
      24. 7.5.24 ICUTnm CONFIG Register
        1. 7.5.24.1 ICUT21 CONFIG Register
        2. 7.5.24.2 ICUT43 CONFIG Register
        3. 7.5.24.3 Bits Description
      25. 7.5.25 Temperature Register
      26. 7.5.26 Input Voltage Register
      27. 7.5.27 Port n Current Register
        1. 7.5.27.1 Port 1 Current Register
        2. 7.5.27.2 Port 2 Current Register
        3. 7.5.27.3 Port 3 Current Register
        4. 7.5.27.4 Port 4 Current Register
      28. 7.5.28 Port n Voltage Register
        1. 7.5.28.1 Port 1 Voltage Register
        2. 7.5.28.2 Port 2 Voltage Register
        3. 7.5.28.3 Port 3 Voltage Register
        4. 7.5.28.4 Port 4 Voltage Register
      29. 7.5.29 PoE Plus Register
      30. 7.5.30 Firmware Revision Register
      31. 7.5.31 I2C Watchdog Register
      32. 7.5.32 Device ID Register
      33. 7.5.33 Cool Down/Gate Drive Register
      34. 7.5.34 Port n Detect Resistance Register
        1. 7.5.34.1 Port 1 Detect Resistance Register
          1. 7.5.34.1.1 Port 2 Detect Resistance Register
          2. 7.5.34.1.2 Port 3 Detect Resistance Register
          3. 7.5.34.1.3 Port 4 Detect Resistance Register
      35. 7.5.35 Port n Detect Voltage Difference Register
        1. 7.5.35.1 Port 1 Detect Voltage Difference Register
        2. 7.5.35.2 Port 2 Detect Voltage Difference Register
        3. 7.5.35.3 Port 3 Detect Voltage Difference Register
        4. 7.5.35.4 Port 4 Detect Voltage Difference Register
      36. 7.5.36 Reserved Registers
  8. 8 Application and Implementation
    1. 8.1 Introduction to PoE
    2. 8.2 Application Information
      1. 8.2.1 Kelvin Current Sensing Resistor
      2. 8.2.2 Connections on Unused Ports
    3. 8.3 Typical Application
      1. 8.3.1 Two Port, Auto Mode Application with External Port Reset
        1. 8.3.1.1 Design Requirements
      2. 8.3.2 Four Port, Auto Mode Application
        1. 8.3.2.1 Design Requirements
      3. 8.3.3 Eight Port, Semi-Auto Mode Application Using MSP430 Micro-Controller
        1. 8.3.3.1 Design Requirements
      4. 8.3.4 Detailed Design Procedure
        1. 8.3.4.1 Power Pin Bypass Capacitors
        2. 8.3.4.2 Per Port Components
        3. 8.3.4.3 System Level Components (not shown in the schematic diagrams)
      5. 8.3.5 Application Curves
    4. 8.4 System Examples
      1. 8.4.1 Overcurrent and Overload Protection
      2. 8.4.2 Inrush Protection
      3. 8.4.3 ICUT Current Limit
      4. 8.4.4 Foldback Protection (ILIM)
      5. 8.4.5 Kelvin Current Sensing Resistor
  9. 9 Power Supply Recommendations
    1. 9.1 VDD
    2. 9.2 VPWR
    3. 9.3 VPWR-RESET Sequencing
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Port Current Kelvin Sensing
    2. 10.2 Layout Example
      1. 10.2.1 Component Placement and Routing Guidelines
        1. 10.2.1.1 Power Pin Bypass Capacitors
        2. 10.2.1.2 Per-Port Components
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Community Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

8.2 Application Information

The TPS23861 is a four port, IEEE 802.3at PoE PSE controller and can be used in very simple, low port count, automatic or high port count micro-controller managed applications.

Subsequent sections describe detailed design procedures for applications with different requirements including host control.

TPS23861 fourport_lusbw2.gifFigure 46. Automatic 4-Port Operation Schematic

The schematic of Figure 46 depicts automatic mode operation of the TPS23861, providing turnkey functionality ready to power PoE loads. No connection to the I2C bus or any type of host control is required. In Figure 46 the TPS23861 automatically:

  1. Performs load detection.
  2. Performs classification including type-2 (two-finger) of up to Class 4 loads.
  3. Enables power with protective foldback current limiting, and ICUT value based on load class.
  4. Shuts down in the event of fault loads and shorts.
  5. Performs Maintain Power Signature function to ensure removal of power if load is disconnected.
  6. Undervoltage lock out occurs if VPWR falls below VPUV_F (typical 26.5 V).

Following a power-off command, disconnect or shutdown due to a start, ICUT or ILIM fault, the port powers down. Following port power off due to a power off command or disconnect, the TPS23861 continues automatic operation starting with a detection cycle. If the shutdown is due to a start, ICUT or ILIM fault, the TPS23861 enters into a cool-down period. After the end of the cool-down period the TPS23861 continues automatic operation starting with a detection cycle.

The TPS23861 will not automatically apply power to a port under the following circumstances:

  • The detect status is not Resistance Valid.
  • If the classification status is overcurrent, class mismatch, or unknown.