SLVSF02E march   2019  – may 2023 TPS23881

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Revision History
  6. 5 Device Comparison Table
  7. 6 Pin Configuration and Functions
    1. 6.1 Detailed Pin Description
  8. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Typical Characteristics
  9. 8 Parameter Measurement Information
    1. 8.1 Timing Diagrams
  10. 9 Detailed Description
    1. 9.1 Overview
      1. 9.1.1 Operating Modes
        1. 9.1.1.1 Auto
        2. 9.1.1.2 Semiauto
        3. 9.1.1.3 Manual and Diagnostic
        4. 9.1.1.4 Power Off
      2. 9.1.2 PoE Compliance Terminology
      3. 9.1.3 Channel versus Port Terminology
      4. 9.1.4 Requested Class versus Assigned Class
      5. 9.1.5 Power Allocation and Power Demotion
      6. 9.1.6 Programmable SRAM
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1 Port Remapping
      2. 9.3.2 Port Power Priority
      3. 9.3.3 Analog-to-Digital Converters (ADC)
      4. 9.3.4 I2C Watchdog
      5. 9.3.5 Current Foldback Protection
    4. 9.4 Device Functional Modes
      1. 9.4.1 Detection
      2. 9.4.2 Connection Check
      3. 9.4.3 Classification
      4. 9.4.4 DC Disconnect
    5. 9.5 I2C Programming
      1. 9.5.1 I2C Serial Interface
    6. 9.6 Register Maps
      1. 9.6.1 Complete Register Set
      2. 9.6.2 Detailed Register Descriptions
        1. 9.6.2.1  INTERRUPT Register
        2. 9.6.2.2  INTERRUPT MASK Register
        3. 9.6.2.3  POWER EVENT Register
        4. 9.6.2.4  DETECTION EVENT Register
        5. 9.6.2.5  FAULT EVENT Register
        6. 9.6.2.6  START/ILIM EVENT Register
        7. 9.6.2.7  SUPPLY and FAULT EVENT Register
          1. 9.6.2.7.1 Detected SRAM Faults and "Safe Mode"
            1. 9.6.2.7.1.1 ULA (Ultra Low Alpha) Package Option: TPS23881A
        8. 9.6.2.8  CHANNEL 1 DISCOVERY Register
        9. 9.6.2.9  CHANNEL 2 DISCOVERY Register
        10. 9.6.2.10 CHANNEL 3 DISCOVERY Register
        11. 9.6.2.11 CHANNEL 4 DISCOVERY Register
        12. 9.6.2.12 POWER STATUS Register
        13. 9.6.2.13 PIN STATUS Register
        14. 9.6.2.14 OPERATING MODE Register
        15. 9.6.2.15 DISCONNECT ENABLE Register
        16. 9.6.2.16 DETECT/CLASS ENABLE Register
        17. 9.6.2.17 Power Priority / 2Pair PCUT Disable Register Name
        18. 9.6.2.18 TIMING CONFIGURATION Register
        19. 9.6.2.19 GENERAL MASK Register
        20. 9.6.2.20 DETECT/CLASS RESTART Register
        21. 9.6.2.21 POWER ENABLE Register
        22. 9.6.2.22 RESET Register
        23. 9.6.2.23 ID Register
        24. 9.6.2.24 Connection Check and Auto Class Status Register
        25. 9.6.2.25 2-Pair Police Ch-1 Configuration Register
        26. 9.6.2.26 2-Pair Police Ch-2 Configuration Register
        27. 9.6.2.27 2-Pair Police Ch-3 Configuration Register
        28. 9.6.2.28 2-Pair Police Ch-4 Configuration Register
        29. 9.6.2.29 Capacitance (Legacy PD) Detection
        30. 9.6.2.30 Power-on Fault Register
        31. 9.6.2.31 PORT RE-MAPPING Register
        32. 9.6.2.32 Channels 1 and 2 Multi Bit Priority Register
        33. 9.6.2.33 Channels 3 and 4 Multi Bit Priority Register
        34. 9.6.2.34 4-Pair Wired and Port Power Allocation Register
        35. 9.6.2.35 4-Pair Police Ch-1 and 2 Configuration Register
        36. 9.6.2.36 4-Pair Police Ch-3 and 4 Configuration Register
        37. 9.6.2.37 TEMPERATURE Register
        38. 9.6.2.38 4-Pair Fault Configuration Register
        39. 9.6.2.39 INPUT VOLTAGE Register
        40. 9.6.2.40 CHANNEL 1 CURRENT Register
        41. 9.6.2.41 CHANNEL 2 CURRENT Register
        42. 9.6.2.42 CHANNEL 3 CURRENT Register
        43. 9.6.2.43 CHANNEL 4 CURRENT Register
        44. 9.6.2.44 CHANNEL 1 VOLTAGE Register
        45. 9.6.2.45 CHANNEL 2 VOLTAGE Register
        46. 9.6.2.46 CHANNEL 3 VOLTAGE Register
        47. 9.6.2.47 CHANNEL 4 VOLTAGE Register
        48. 9.6.2.48 2x FOLDBACK SELECTION Register
        49. 9.6.2.49 FIRMWARE REVISION Register
        50. 9.6.2.50 I2C WATCHDOG Register
        51. 9.6.2.51 DEVICE ID Register
        52. 9.6.2.52 CHANNEL 1 DETECT RESISTANCE Register
        53. 9.6.2.53 CHANNEL 2 DETECT RESISTANCE Register
        54. 9.6.2.54 CHANNEL 3 DETECT RESISTANCE Register
        55. 9.6.2.55 CHANNEL 4 DETECT RESISTANCE Register
        56. 9.6.2.56 CHANNEL 1 DETECT CAPACITANCE Register
        57. 9.6.2.57 CHANNEL 2 DETECT CAPACITANCE Register
        58. 9.6.2.58 CHANNEL 3 DETECT CAPACITANCE Register
        59. 9.6.2.59 CHANNEL 4 DETECT CAPACITANCE Register
        60. 9.6.2.60 CHANNEL 1 ASSIGNED CLASS Register
        61. 9.6.2.61 CHANNEL 2 ASSIGNED CLASS Register
        62. 9.6.2.62 CHANNEL 3 ASSIGNED CLASS Register
        63. 9.6.2.63 CHANNEL 4 ASSIGNED CLASS Register
        64. 9.6.2.64 AUTO CLASS CONTROL Register
        65. 9.6.2.65 CHANNEL 1 AUTO CLASS POWER Register
        66. 9.6.2.66 CHANNEL 2 AUTO CLASS POWER Register
        67. 9.6.2.67 CHANNEL 3 AUTO CLASS POWER Register
        68. 9.6.2.68 CHANNEL 4 AUTO CLASS POWER Register
        69. 9.6.2.69 ALTERNATIVE FOLDBACK Register
        70. 9.6.2.70 SRAM CONTROL Register
          1. 9.6.2.70.1 SRAM START ADDRESS (LSB) Register
          2. 9.6.2.70.2 SRAM START ADDRESS (MSB) Register
  11. 10Application and Implementation
    1. 10.1 Application Information
      1. 10.1.1 Introduction to PoE
        1. 10.1.1.1 2-Pair Versus 4-Pair Power and the New IEEE802.3bt Standard
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedure
        1. 10.2.2.1 Connections on Unused Channels
        2. 10.2.2.2 Power Pin Bypass Capacitors
        3. 10.2.2.3 Per Port Components
        4. 10.2.2.4 System Level Components (not Shown in the Schematic Diagrams)
      3. 10.2.3 Application Curves
  12. 11Power Supply Recommendations
    1. 11.1 VDD
    2. 11.2 VPWR
  13. 12Layout
    1. 12.1 Layout Guidelines
      1. 12.1.1 Kelvin Current Sensing Resistors
    2. 12.2 Layout Example
      1. 12.2.1 Component Placement and Routing Guidelines
        1. 12.2.1.1 Power Pin Bypass Capacitors
        2. 12.2.1.2 Per-Port Components
  14. 13Device and Documentation Support
    1. 13.1 Documentation Support
      1. 13.1.1 Related Documentation
    2. 13.2 Receiving Notification of Documentation Updates
    3. 13.3 Support Resources
    4. 13.4 Trademarks
    5. 13.5 Electrostatic Discharge Caution
    6. 13.6 Glossary
  15. 14Mechanical, Packaging, and Orderable Information

Package Options

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

9.6.2.34 4-Pair Wired and Port Power Allocation Register

COMMAND = 29h with 1 Data Byte, Read/Write

Figure 9-41 4-Pair Wired and Power Allocation Register Format
76543210
4PW34MC34_2MC34_1MC34_04PW12MC12_2MC12_1MC12_0
R/W-0R/W-0R/W-0R/W-0R/W-0R/W-0R/W-0R/W–0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 9-44 4-Pair Wired and Power Allocation Register Field Descriptions
BitFieldTypeResetDescription
7 , 34PWnnR/W04-Pair wired configuration bits

4PWnn = 1: Channels 3/4 or 1/2 are wired in a 4-pair configuration

4PWnn = 0: Channels 3/4 or 1/2 are wired in 2-pair configurations

6 - 4 , 2 - 0MCnn_2-0R/W0MCnn_2-0: Port Power Allocation bits. These bits set the maximum power classification level that a given Port (2-Pair or 4-Pair) is allowed to power on

In Semi Auto mode these bits need to be set prior to issuing a PWONn command, while in Auto mode these bits need to be set prior to setting the DETE and CLE bits in 0x14.

Table 9-45 4-Pair Wired and Power Allocation Settings
4PWnnMCnn_2MCnn_1MCnn_0Power Allocation
00002-Pair 15.4W
0001Reserved
0010Reserved
00112-Pair 30W
01xxReserved
10004-Pair 15.4W
1001Reserved
1010Reserved
10114-Pair 30W (Class 4)
11004-Pair 45W (Class 5)
11014-Pair 60W (Class 6)
11104-Pair 75W (Class 7)
11114-Pair 90W (Class 8)

Refer to Table 9-2 and Table 9-3 for more details on the application of Power Demotion and the relationship between the Power Allocation settings and the resulting Assigned Class.

Note:

In order to prevent any unexpected behavior the setting the 4PWnn bits should only be done immediately following a Power On Reset (POR) event while the ports are still in OFF mode.

Note:

The Power Allocation (0x29h) value needs to be set prior to issuing a PWON command in Semi Auto or Auto modes, and prior to setting the DETE and CLE bits in Auto mode. Any changes to the Power Allocation value after a PWON command is given may be ignored.

Note:

For 4-pair dual signature PDs, the odd numbered Channels takes priority over the even numbered Channels. Thus, an even numbered Channel will be powered based on the difference between the total power allocated and what the odd Channel classified as.

For example if a dual signature PD contained two 45W PDs and the PSEs power allocation was set to 60W, the odd numbered Channel will be powered at 45W while the even numbered Channel will be limited to 15W.

Note:

For 2-Pair wired ports, the MCnn_2-0 bits set the power allocation settings for both channels 1 and 2 and 3 and 4 concurrently.

It is possible to have channels 3 and 4 set to 15.4W while channels 1 and 2 are set to 30W, but it is not possible to have different power allocation settings between channels 1 and 2 or 3 and 4