JAJSHI3C March   2019  – October 2019 TPS23881


  1. 特長
  2. アプリケーション
  3. 概要
    1.     Device Images
      1.      概略回路図
  4. 改訂履歴
  5. 概要(続き)
  6. Device Comparison Table
  7. Pin Configuration and Functions
    1.     Pin Functions
    2. 7.1 Detailed Pin Description
  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. Parameter Measurement Information
    1. 9.1 Timing Diagrams
  10. 10Detailed Description
    1. 10.1 Overview
      1. 10.1.1 Operating Modes
        1. Auto
        2. Autonomous
        3. Semiauto
        4. Manual/Diagnostic
        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.  INTERRUPT Register
          1. Table 5. INTERRUPT Register Field Descriptions
        2.  INTERRUPT MASK Register
          1. Table 6. INTERRUPT MASK Register Field Descriptions
        3.  POWER EVENT Register
          1. Table 7. POWER EVENT Register Field Descriptions
        4.  DETECTION EVENT Register
          1. Table 8. DETECTION EVENT Register Field Descriptions
        5.  FAULT EVENT Register
          1. Table 9. FAULT EVENT Register Field Descriptions
        6.  START/ILIM EVENT Register
          1. Table 10. START/ILIM EVENT Register Field Descriptions
        7.  SUPPLY and FAULT EVENT Register
          1. Table 11.  SUPPLY and FAULT EVENT Register Field Descriptions
          2. Detected SRAM Faults and "Safe Mode"
            1. ULA (Ultra Low Alpha) Package Option: TPS23881A
        8.  CHANNEL 1 DISCOVERY Register
        9.  CHANNEL 2 DISCOVERY Register
        10. CHANNEL 3 DISCOVERY Register
        11. CHANNEL 4 DISCOVERY Register
          1. Table 12. CHANNEL n DISCOVERY Register Field Descriptions
        12. POWER STATUS Register
          1. Table 13. POWER STATUS Register Field Descriptions
        13. PIN STATUS Register
          1. Table 14.   PIN STATUS Register Field Descriptions
          2. AUTONOMOUS MODE
        14. OPERATING MODE Register
          1. Table 16. OPERATING MODE Register Field Descriptions
        15. DISCONNECT ENABLE Register
          1. Table 20. DISCONNECT ENABLE Register Field Descriptions
        16. DETECT/CLASS ENABLE Register
          1. Table 21. DETECT/CLASS ENABLE Register Field Descriptions
        17. Power Priority / 2Pair PCUT Disable Register Name
          1. Table 22. Power Priority / 2P-PCUT Disable Register Field Descriptions
        18. TIMING CONFIGURATION Register
          1. Table 24. TIMING CONFIGURATION Register Field Descriptions
        19. GENERAL MASK Register
          1. Table 25. GENERAL MASK Register Field Descriptions
        20. DETECT/CLASS RESTART Register
          1. Table 27. DETECT/CLASS RESTART Register Field Descriptions
        21. POWER ENABLE Register
          1. Table 28. POWER ENABLE Register Field Descriptions
        22. RESET Register
          1. Table 32. RESET Register Field Descriptions
        23. ID Register
          1. Table 34. ID Register Field Descriptions
        24. Connection Check and Auto Class Status Register
          1. Table 35. Connection Check and Auto Class Field Descriptions
        25. 2-Pair Police Ch-1 Configuration Register
        26. 2-Pair Police Ch-2 Configuration Register
        27. 2-Pair Police Ch-3 Configuration Register
        28. 2-Pair Police Ch-4 Configuration Register
          1. Table 36. 2-Pair Policing Register Fields Descriptions
        29. Capacitance (Legacy PD) Detection
          1. Table 39. Capacitance Detection Register Field Descriptions
        30. Power-on Fault Register
          1. Table 40. Power-on Fault Register Field Descriptions
        31. PORT RE-MAPPING Register
          1. Table 41. PORT RE-MAPPING Register Field Descriptions
        32. Channels 1 and 2 Multi Bit Priority Register
        33. Channels 3 and 4 Multi Bit Priority Register
          1. Table 42. Channels n MBP Register Field Descriptions
        34. 4-Pair Wired and Port Power Allocation Register
          1. Table 44. 4-Pair Wired and Power Allocation Register Field Descriptions
        35. 4-Pair Police Ch-1 and 2 Configuration Register
        36. 4-Pair Police Ch-3 and 4 Configuration Register
          1. Table 46. 4-Pair Police Register Field Descriptions
        37. TEMPERATURE Register
          1. Table 48. TEMPERATURE Register Field Descriptions
        38. 4-Pair Fault Configuration Register
          1. Table 49. 4-Pair Fault Register Field Descriptions
        39. INPUT VOLTAGE Register
          1. Table 50. INPUT VOLTAGE Register Field Descriptions
        40. CHANNEL 1 CURRENT Register
        41. CHANNEL 2 CURRENT Register
        42. CHANNEL 3 CURRENT Register
        43. CHANNEL 4 CURRENT Register
          1. Table 51. CHANNEL n CURRENT Register Field Descriptions
        44. CHANNEL 1 VOLTAGE Register
        45. CHANNEL 2 VOLTAGE Register
        46. CHANNEL 3 VOLTAGE Register
        47. CHANNEL 4 VOLTAGE Register
          1. Table 52. CHANNEL n VOLTAGE Register Field Descriptions
        48. 2x FOLDBACK SELECTION Register
          1. Table 53. 2x FOLDBACK SELECTION Register Field Descriptions
        49. FIRMWARE REVISION Register
          1. Table 54. FIRMWARE REVISION Register Field Descriptions
        50. I2C WATCHDOG Register
          1. Table 55. I2C WATCHDOG Register Field Descriptions
        51. DEVICE ID Register
          1. Table 57. DEVICE ID Register Field Descriptions
        52. CHANNEL 1 DETECT RESISTANCE Register
        53. CHANNEL 2 DETECT RESISTANCE Register
        54. CHANNEL 3 DETECT RESISTANCE Register
        55. CHANNEL 4 DETECT RESISTANCE Register
          1. Table 58. DETECT RESISTANCE Register Fields Descriptions
          1. Table 59. DETECT CAPACITANCE Register Fields Descriptions
        60. CHANNEL 1 ASSIGNED CLASS Register
        61. CHANNEL 2 ASSIGNED CLASS Register
        62. CHANNEL 3 ASSIGNED CLASS Register
        63. CHANNEL 4 ASSIGNED CLASS Register
          1. Table 60. CHANNEL n ASSIGNED CLASS Register Field Descriptions
        64. AUTO CLASS CONTROL Register
          1. Table 63. AUTO CLASS CONTROL Register Field Descriptions
        65. CHANNEL 1 AUTO CLASS POWER Register
        66. CHANNEL 2 AUTO CLASS POWER Register
        67. CHANNEL 3 AUTO CLASS POWER Register
        68. CHANNEL 4 AUTO CLASS POWER Register
          1. Table 65. AUTO CLASS POWER Register Fields Descriptions
        69. ALTERNATIVE FOLDBACK Register
          1. Table 66. ALTERNATIVE FOLDBACK Register Field Descriptions
        70. SRAM CONTROL Register
          1. Table 67. SRAM CONTROL Register Field Descriptions
        71. SRAM START ADDRESS (LSB) Register
        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. 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. Connections on Unused Channels
        2. Power Pin Bypass Capacitors
        3. Per Port Components
        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. Power Pin Bypass Capacitors
        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




COMMAND = 12h with 1 Data Byte, Read/Write

Figure 58. OPERATING MODE Register Format
7 6 5 4 3 2 1 0
C4M1 C4M0 C3M1 C3M0 C2M1 C2M0 C1M1 C1M0
R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset

Table 16. OPERATING MODE Register Field Descriptions

Bit Field Type Reset Description
7-0 CnM1–CnM0 R/W 0 Each pair of bits configures the operating mode per channel.

The selection is as following:

M1 M0 Operating Mode
0 0 OFF
0 1 Diagnostic/Manual
1 0 Semiauto
1 1 Auto

For a 4-pair wired port, both channels must be set to the same operating mode. Otherwise, the port will not conduct discovery, and any turn on commands will be ignored.



In OFF mode, the Channel is OFF and neither detection nor classification is performed independent of the DETE, CLSE or PWON bits.

The table below depicts what bits will be cleared when a channel is changed to OFF mode from any other operating mode:

Table 17. Transition to OFF Mode

Register Bits to be reset
0x04 CLSCn and DETCn
0x06 DISFn and PCUTn
0x08 STRTn and ILIMn
0x0A/B PCUTnn
0x0C-0F Requested Class and Detection
0x10 PGn and PEn
0x14 CLEn and DETEn
0x1C ACn and CCnn
0x1E-21 2P Policing set to 0xFFh
0x24 PFn
0x2A-2B 4P Policing set to 0xFFh
0x2D NLMnn, NCTnn, 4PPCTnn, and DCDTnn
0x30-3F Channel Voltage and Current Measurements
0x40 2xFBn
0x44 - 47 Detection Resistance Measurements
0x4C-4F Assigned Class and Previous Class
0x51-54 Autoclass Measurement



it may take upwards of 5 ms before all of the registers are cleared following a change to OFF mode.

Only the bits associated with the channel/port ("n") being set into OFF mode will be cleared. Those bits associated with channels/ports remaining in operation will not be changed.

In the event either the PGn or PEn bits were changed from a 1 to a zero, the corresponding PGCn and PECn bits will be set in the POWER EVENT register 0x02h.

Also, a change of mode from semiauto to manual/diagnostic mode or OFF mode will cancel any ongoing cooldown time period.



In Manual/Diagnostic mode, there is no automatic state change. The channel remains idle until DETE, CLSE (0x14h or 0x18h), or PWON command is provided. Upon the setting of the DETE and/or CLSE bits, the channel will perform a singular detection and/or classification cycle on the corresponding channel.



Setting a PWONn bit in register 0x19 results in the immediate turn on of that channel.

There is no Assigned Class assigned for ports/channels powered out of Manual/Diagnostic mode. Any settings such as the port power policing and 1x/2x foldback selection that are typically configure based on the assigned class result need to manually configured by the user.

For 4-Pair wired ports (4PWnn bit in 0x29 = 1):

Setting the DETE or CLSE bits on only one channel will result in detection and/or classification only being done on that channel, and Connection Check will not be preformed.

Setting the DETE bits for both channels during the same I2C operation will result in detection cycles being completed on both channels, and if the detection results are valid, connection check will also be completed.

Setting the CLSE bits for both channels during the same I2C operation will result in staggered classification measurements being done on both channels


Setting a PWONn bit in register 0x19 results in the immediate turn on of that channel.


DC Disconnect for 4-Pair ports power on in Manual/Diagnostic mode will behave as independent channels. Thus, if either channel current falls below VIMIN for longer than tMPDO , that channel will be disabled and a disconnect fault will be set (DISFn bits in register 0x06/7).

Table 18. Channel Behavior in Diagnostic/Manual Mode

CLEn DETn PWONn Channel Operation
0 0 0 Idle
0 1 0 Single Detection measurement (Connection check completed if 4P wired and DETE bits are set for both channels)
1 0 0 Single Classification measurement
1 1 0 Single Detection and Classification measurement done. (Connection check completed if 4P wired and both DETE and CLE bits are set for both channels)
- - 1 Channel immediate turns on without any detection or classification being performed


In Semi Auto mode, as long as the Channel is unpowered, detection and classifications may be performed continuously depending if the corresponding class and detect enable bits are set (register 0x14h).

Table 19. Channel Behavior in Semi Auto Mode

CLEn DETn Channel Operation
0 0 Idle
0 1 Cycling Detection Measurements only
1 0 Idle
1 1 Cycling Detection and Classification Measurements


If two channels are configured as a 4-pair wired port, a connection check measurement will be performed once a valid detection result is seen on one of the channel

For a 4-Pair Dual Signature PD that has only one channel powered, the unpowered channel will resume detect and class provided the DETE and CLE bits are set for that channel in 0x14h.



In Auto mode, channels will automatically power on any valid detection and classification signature based on the Port Power Allocation settings in 0x29. The channels will remain idle until DETE and CLSE (0x14 or 0x18) are set, or a PWON command is given.

Prior to setting DETE and CLE or sending a PWON command in AUTO mode, the following registers need to be configured according to the system requirements and configuration:

Register Bits
0x26 Port Re-mapping
0x29 4-Pair Wired and Port Power Allocation
0x50 Auto AC Enable
0x55 Alternative Inrush and Powered Foldback Enable


Changes to these registers after the DETE and CLE bits are set in Auto mode may result in undesired or non IEEE complaint operation.

The following registers may be configured or changed after turn on if changes to the default operation are desired as these values are internally set during power on based on the port configuration and resulting assigned PD class:

Register Bits
0x1E-21 2-Pair Policing
0x2A-2B 4-Pair Policing
0x2D 4P Pcut Enable and DC Disconnect Threshold bits
0x40 2x Foldback Enable