SLUSC25B February   2015  – October 2026 TPS2388

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
    1. 4.1 Detailed Pin Description
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Timing Requirements
    7. 5.7 Switching Characteristics
    8. 5.8 Typical Characteristics
  7. 6 Parameter Measurement Information
    1. 6.1 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 Port Remapping
      2. 7.3.2 Port Power Priority
      3. 7.3.3 A/D Converter
      4. 7.3.4 I2C Watchdog
      5. 7.3.5 Foldback Protection
    4. 7.4 Device Functional Modes
      1. 7.4.1 Port Operating Modes
        1. 7.4.1.1 Semiauto
        2. 7.4.1.2 Manual
        3. 7.4.1.3 Power Off
      2. 7.4.2 Detection
      3. 7.4.3 Classification
      4. 7.4.4 DC Disconnect
    5. 7.5 Programming
      1. 7.5.1 I2C Serial Interface
    6. 7.6 Register Maps
      1. 7.6.1  Complete Register Set
      2. 7.6.2  INTERRUPT Register
      3. 7.6.3  INTERRUPT MASK Register
      4. 7.6.4  POWER EVENT Register
      5. 7.6.5  DETECTION EVENT Register
      6. 7.6.6  FAULT EVENT Register
      7. 7.6.7  START/ILIM EVENT Register
      8. 7.6.8  SUPPLY EVENT Register
      9. 7.6.9  PORT 1 STATUS Register
      10. 7.6.10 PORT 2 STATUS Register
      11. 7.6.11 PORT 3 STATUS Register
      12. 7.6.12 PORT 4 STATUS Register
      13. 7.6.13 POWER STATUS Register
      14. 7.6.14 Pin Status Register
      15. 7.6.15 OPERATING MODE Register
      16. 7.6.16 DISCONNECT ENABLE Register
      17. 7.6.17 DETECT/CLASS ENABLE Register
      18. 7.6.18 Port Power Priority/ICUT Disable Register Name
      19. 7.6.19 TIMING CONFIGURATION Register
      20. 7.6.20 GENERAL MASK Register
      21. 7.6.21 DETECT/CLASS RESTART Register
      22. 7.6.22 POWER ENABLE Register
      23. 7.6.23 RESET Register
      24. 7.6.24 ID Register
      25. 7.6.25 Police 21 Configuration Register
      26. 7.6.26 Police 43 Configuration Register
      27. 7.6.27 IEEE Power Enable Register
      28. 7.6.28 Power-on Fault Register
      29. 7.6.29 PORT RE-MAPPING Register
      30. 7.6.30 Port 21 Multi Bit Priority Register
      31. 7.6.31 Port 43 Multi Bit Priority Register
      32. 7.6.32 TEMPERATURE Register
      33. 7.6.33 INPUT VOLTAGE Register
      34. 7.6.34 PORT 1 CURRENT Register
      35. 7.6.35 PORT 2 CURRENT Register
      36. 7.6.36 PORT 3 CURRENT Register
      37. 7.6.37 PORT 4 CURRENT Register
      38. 7.6.38 PORT 1 VOLTAGE Register
      39. 7.6.39 PORT 2 VOLTAGE Register
      40. 7.6.40 PORT 3 VOLTAGE Register
      41. 7.6.41 PORT 4 VOLTAGE Register
      42. 7.6.42 PoE Plus Register
      43. 7.6.43 FIRMWARE REVISION
      44. 7.6.44 I2C WATCHDOG Register
      45. 7.6.45 DEVICE ID Register
      46. 7.6.46 PORT 1 DETECT RESISTANCE Register
      47. 7.6.47 PORT 2 DETECT RESISTANCE Register
      48. 7.6.48 PORT 3 DETECT RESISTANCE Register
      49. 7.6.49 PORT 4 DETECT RESISTANCE Register
  9. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Introduction to PoE
      2. 8.1.2 TPS2388 Application
      3. 8.1.3 Kelvin Current Sensing Resistor
      4. 8.1.4 Connections on Unused Ports
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Power Pin Bypass Capacitors
        2. 8.2.2.2 Per Port Components
        3. 8.2.2.3 System Level Components (not shown in the schematic diagrams)
      3. 8.2.3 Application Curves
    3. 8.3 Power Supply Recommendations
      1. 8.3.1 VDD
      2. 8.3.2 VPWR
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
        1. 8.4.1.1 Port Current Kelvin Sensing
      2. 8.4.2 Layout Example
        1. 8.4.2.1 Component Placement and Routing Guidelines
          1. 8.4.2.1.1 Power Pin Bypass Capacitors
          2. 8.4.2.1.2 Per-Port Components
  10. 9 Device and Documentation Support
    1. 9.1 Receiving Notification of Documentation Updates
    2. 9.2 Support Resources
    3. 9.3 Trademarks
    4. 9.4 Electrostatic Discharge Caution
    5. 9.5 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

7.4.2 Detection

To eliminate the possibility of false detection, the TPS2388 uses a TI proprietary 4-point detection method to determine the signature resistance of the PD device. False detection of a 25kΩ signature can occur with 2-point detection type PSEs in noisy environments or if the load is highly capacitive.

Both detection 1 and detection 2 are merged into a single detection function which is repeated. Detection 1 applies I1 (160μA) to a port, waits 60ms, then measures the port voltage V1 with the integrating ADC. Detection 2 applies I2 (270μA) to a port, waits 60ms, then measures the port voltage V2. The process is repeated a second time. Multiple comparisons and calculations are performed on all four measurement point combinations to eliminate the effects of a non-linear or hysteretic PD signature. The resulting port signature is then sorted into the appropriate category.

Note:

The detection resistance measurement result is also available in the Port Detect Resistance register.