JAJSHI3C March   2019  – October 2019 TPS23881

PRODUCTION DATA.  

  1. 1 特長
  2. 2 アプリケーション
  3. 3 概要
    1.     Device Images
      1.      概略回路図
  4. 4 改訂履歴
  5. 5 概要（続き）
  6. 6 Device Comparison Table
  7. 7 Pin Configuration and Functions
    1.     Pin Functions
    2. 7.1 Detailed Pin Description
  8. 8 Specifications
    1. 8.1 Absolute Maximum Ratings
    2. 8.2 ESD Ratings
    3. 8.3 Recommended Operating Conditions
    4. 8.4 Thermal Information
    5. 8.5 Electrical Characteristics
    6. 8.6 Typical Characteristics
  9. 9 Parameter Measurement Information
    1. 9.1 Timing Diagrams
  10. 10Detailed Description
    1. 10.1 Overview
      1. 10.1.1 Operating Modes
        1. 10.1.1.1 Auto
        2. 10.1.1.2 Autonomous
        3. 10.1.1.3 Semiauto
        4. 10.1.1.4 Manual/Diagnostic
        5. 10.1.1.5 Power Off
      2. 10.1.2 Channel versus Port Terminology
      3. 10.1.3 Requested Class versus Assigned Class
      4. 10.1.4 Power Allocation and Power Demotion
    2. 10.2 Functional Block Diagram
    3. 10.3 Feature Description
      1. 10.3.1 Port Remapping
      2. 10.3.2 Port Power Priority
      3. 10.3.3 Analog-to-Digital Converters (ADC)
      4. 10.3.4 I2C Watchdog
      5. 10.3.5 Current Foldback Protection
    4. 10.4 Device Functional Modes
      1. 10.4.1 Detection
      2. 10.4.2 Connection Check
      3. 10.4.3 Classification
      4. 10.4.4 DC Disconnect
    5. 10.5 I2C Programming
      1. 10.5.1 I2C Serial Interface
    6. 10.6 Register Maps
      1. 10.6.1 Complete Register Set
      2. 10.6.2 Detailed Register Descriptions
        1. 10.6.2.1  INTERRUPT Register
          1. Table 5. INTERRUPT Register Field Descriptions
        2. 10.6.2.2  INTERRUPT MASK Register
          1. Table 6. INTERRUPT MASK Register Field Descriptions
        3. 10.6.2.3  POWER EVENT Register
          1. Table 7. POWER EVENT Register Field Descriptions
        4. 10.6.2.4  DETECTION EVENT Register
          1. Table 8. DETECTION EVENT Register Field Descriptions
        5. 10.6.2.5  FAULT EVENT Register
          1. Table 9. FAULT EVENT Register Field Descriptions
        6. 10.6.2.6  START/ILIM EVENT Register
          1. Table 10. START/ILIM EVENT Register Field Descriptions
        7. 10.6.2.7  SUPPLY and FAULT EVENT Register
          1. Table 11.  SUPPLY and FAULT EVENT Register Field Descriptions
          2. 10.6.2.7.1 Detected SRAM Faults and "Safe Mode"
            1. 10.6.2.7.1.1 ULA (Ultra Low Alpha) Package Option: TPS23881A
        8. 10.6.2.8  CHANNEL 1 DISCOVERY Register
        9. 10.6.2.9  CHANNEL 2 DISCOVERY Register
        10. 10.6.2.10 CHANNEL 3 DISCOVERY Register
        11. 10.6.2.11 CHANNEL 4 DISCOVERY Register
          1. Table 12. CHANNEL n DISCOVERY Register Field Descriptions
        12. 10.6.2.12 POWER STATUS Register
          1. Table 13. POWER STATUS Register Field Descriptions
        13. 10.6.2.13 PIN STATUS Register
          1. Table 14.   PIN STATUS Register Field Descriptions
          2. 10.6.2.13.1 AUTONOMOUS MODE
        14. 10.6.2.14 OPERATING MODE Register
          1. Table 16. OPERATING MODE Register Field Descriptions
        15. 10.6.2.15 DISCONNECT ENABLE Register
          1. Table 20. DISCONNECT ENABLE Register Field Descriptions
        16. 10.6.2.16 DETECT/CLASS ENABLE Register
          1. Table 21. DETECT/CLASS ENABLE Register Field Descriptions
        17. 10.6.2.17 Power Priority / 2Pair PCUT Disable Register Name
          1. Table 22. Power Priority / 2P-PCUT Disable Register Field Descriptions
        18. 10.6.2.18 TIMING CONFIGURATION Register
          1. Table 24. TIMING CONFIGURATION Register Field Descriptions
        19. 10.6.2.19 GENERAL MASK Register
          1. Table 25. GENERAL MASK Register Field Descriptions
        20. 10.6.2.20 DETECT/CLASS RESTART Register
          1. Table 27. DETECT/CLASS RESTART Register Field Descriptions
        21. 10.6.2.21 POWER ENABLE Register
          1. Table 28. POWER ENABLE Register Field Descriptions
        22. 10.6.2.22 RESET Register
          1. Table 32. RESET Register Field Descriptions
        23. 10.6.2.23 ID Register
          1. Table 34. ID Register Field Descriptions
        24. 10.6.2.24 Connection Check and Auto Class Status Register
          1. Table 35. Connection Check and Auto Class Field Descriptions
        25. 10.6.2.25 2-Pair Police Ch-1 Configuration Register
        26. 10.6.2.26 2-Pair Police Ch-2 Configuration Register
        27. 10.6.2.27 2-Pair Police Ch-3 Configuration Register
        28. 10.6.2.28 2-Pair Police Ch-4 Configuration Register
          1. Table 36. 2-Pair Policing Register Fields Descriptions
        29. 10.6.2.29 Capacitance (Legacy PD) Detection
          1. Table 39. Capacitance Detection Register Field Descriptions
        30. 10.6.2.30 Power-on Fault Register
          1. Table 40. Power-on Fault Register Field Descriptions
        31. 10.6.2.31 PORT RE-MAPPING Register
          1. Table 41. PORT RE-MAPPING Register Field Descriptions
        32. 10.6.2.32 Channels 1 and 2 Multi Bit Priority Register
        33. 10.6.2.33 Channels 3 and 4 Multi Bit Priority Register
          1. Table 42. Channels n MBP Register Field Descriptions
        34. 10.6.2.34 4-Pair Wired and Port Power Allocation Register
          1. Table 44. 4-Pair Wired and Power Allocation Register Field Descriptions
        35. 10.6.2.35 4-Pair Police Ch-1 and 2 Configuration Register
        36. 10.6.2.36 4-Pair Police Ch-3 and 4 Configuration Register
          1. Table 46. 4-Pair Police Register Field Descriptions
        37. 10.6.2.37 TEMPERATURE Register
          1. Table 48. TEMPERATURE Register Field Descriptions
        38. 10.6.2.38 4-Pair Fault Configuration Register
          1. Table 49. 4-Pair Fault Register Field Descriptions
        39. 10.6.2.39 INPUT VOLTAGE Register
          1. Table 50. INPUT VOLTAGE Register Field Descriptions
        40. 10.6.2.40 CHANNEL 1 CURRENT Register
        41. 10.6.2.41 CHANNEL 2 CURRENT Register
        42. 10.6.2.42 CHANNEL 3 CURRENT Register
        43. 10.6.2.43 CHANNEL 4 CURRENT Register
          1. Table 51. CHANNEL n CURRENT Register Field Descriptions
        44. 10.6.2.44 CHANNEL 1 VOLTAGE Register
        45. 10.6.2.45 CHANNEL 2 VOLTAGE Register
        46. 10.6.2.46 CHANNEL 3 VOLTAGE Register
        47. 10.6.2.47 CHANNEL 4 VOLTAGE Register
          1. Table 52. CHANNEL n VOLTAGE Register Field Descriptions
        48. 10.6.2.48 2x FOLDBACK SELECTION Register
          1. Table 53. 2x FOLDBACK SELECTION Register Field Descriptions
        49. 10.6.2.49 FIRMWARE REVISION Register
          1. Table 54. FIRMWARE REVISION Register Field Descriptions
        50. 10.6.2.50 I2C WATCHDOG Register
          1. Table 55. I2C WATCHDOG Register Field Descriptions
        51. 10.6.2.51 DEVICE ID Register
          1. Table 57. DEVICE ID Register Field Descriptions
        52. 10.6.2.52 CHANNEL 1 DETECT RESISTANCE Register
        53. 10.6.2.53 CHANNEL 2 DETECT RESISTANCE Register
        54. 10.6.2.54 CHANNEL 3 DETECT RESISTANCE Register
        55. 10.6.2.55 CHANNEL 4 DETECT RESISTANCE Register
          1. Table 58. DETECT RESISTANCE Register Fields Descriptions
        56. 10.6.2.56 CHANNEL 1 DETECT CAPACITANCE Register
        57. 10.6.2.57 CHANNEL 2 DETECT CAPACITANCE Register
        58. 10.6.2.58 CHANNEL 3 DETECT CAPACITANCE Register
        59. 10.6.2.59 CHANNEL 4 DETECT CAPACITANCE Register
          1. Table 59. DETECT CAPACITANCE Register Fields Descriptions
        60. 10.6.2.60 CHANNEL 1 ASSIGNED CLASS Register
        61. 10.6.2.61 CHANNEL 2 ASSIGNED CLASS Register
        62. 10.6.2.62 CHANNEL 3 ASSIGNED CLASS Register
        63. 10.6.2.63 CHANNEL 4 ASSIGNED CLASS Register
          1. Table 60. CHANNEL n ASSIGNED CLASS Register Field Descriptions
        64. 10.6.2.64 AUTO CLASS CONTROL Register
          1. Table 63. AUTO CLASS CONTROL Register Field Descriptions
        65. 10.6.2.65 CHANNEL 1 AUTO CLASS POWER Register
        66. 10.6.2.66 CHANNEL 2 AUTO CLASS POWER Register
        67. 10.6.2.67 CHANNEL 3 AUTO CLASS POWER Register
        68. 10.6.2.68 CHANNEL 4 AUTO CLASS POWER Register
          1. Table 65. AUTO CLASS POWER Register Fields Descriptions
        69. 10.6.2.69 ALTERNATIVE FOLDBACK Register
          1. Table 66. ALTERNATIVE FOLDBACK Register Field Descriptions
        70. 10.6.2.70 SRAM CONTROL Register
          1. Table 67. SRAM CONTROL Register Field Descriptions
        71. 10.6.2.71 SRAM START ADDRESS (LSB) Register
        72. 10.6.2.72 SRAM START ADDRESS (MSB) Register
          1. Table 68. SRAM START ADDRESS Register Field Descriptions
  11. 11Application and Implementation
    1. 11.1 Application Information
      1. 11.1.1 Autonomous Operation
      2. 11.1.2 Introduction to PoE
        1. 11.1.2.1 2-Pair Versus 4-Pair Power and the New IEEE802.3bt Standard
      3. 11.1.3 SRAM Programming
    2. 11.2 Typical Application
      1. 11.2.1 Design Requirements
      2. 11.2.2 Detailed Design Procedure
        1. 11.2.2.1 Connections on Unused Channels
        2. 11.2.2.2 Power Pin Bypass Capacitors
        3. 11.2.2.3 Per Port Components
        4. 11.2.2.4 System Level Components (not shown in the schematic diagrams)
      3. 11.2.3 Application Curves
  12. 12Power Supply Recommendations
    1. 12.1 VDD
    2. 12.2 VPWR
  13. 13Layout
    1. 13.1 Layout Guidelines
      1. 13.1.1 Kelvin Current Sensing Resistors
    2. 13.2 Layout Example
      1. 13.2.1 Component Placement and Routing Guidelines
        1. 13.2.1.1 Power Pin Bypass Capacitors
        2. 13.2.1.2 Per-Port Components
  14. 14デバイスおよびドキュメントのサポート
    1. 14.1 ドキュメントのサポート
      1. 14.1.1 関連資料
    2. 14.2 ドキュメントの更新通知を受け取る方法
    3. 14.3 サポート・リソース
    4. 14.4 商標
    5. 14.5 静電気放電に関する注意事項
    6. 14.6 Glossary
  15. 15メカニカル、パッケージ、および注文情報

パッケージ・オプション

メカニカル・データ（パッケージ｜ピン）
サーマルパッド・メカニカル・データ
発注情報

10.3.5 Current Foldback Protection

The TPS23881 features two types of foldback mechanisms for complete MOSFET protection.

During inrush, at channel turn on, the foldback is based on the channel voltage as shown in Figure 39. Note that the inrush current profile remains the same, regardless of the state of the 2xFBn bits in register 0x40.

After the channel is powered and the Power Good is valid, a dual-slope operational foldback is used, providing protection against partial and total short-circuit at port output, while still being able to maintain the PD powered during normal transients at the PSE input voltage. Note that setting the 2xFBn bit selects the 2× curve and clearing it selects the 1× curve. See Figure 40.

In addition to the default foldback curves, the TPS23881 has individually enabled alternative foldback curves for both inrush and powered operation. These curves have been designed to accommodate certain loads that do not fully comply with the IEEE standard and requires additional power to be turned on or remain powered. See Figure 39 and Figure 40.

NOTE

If using the Alternative Foldback curves (ALTIRn or ALTFBn = 1), designers need to account for the additional power dissipation that can occur in the FETs under these conditions.
TPS23881 D100_SLUSD53.gifFigure 39. Foldback During Inrush (at Port Turn On): ILIM vs Vport
TPS23881 D200_SLUSD53.gifFigure 40. Foldback When the Port is Already ON: ILIM vs Vdrain