SLVAFG6A December   2022  – November 2023 TPS25762-Q1 , TPS25772-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
    1. 1.1 Terms and Abbreviations
  5. 2 SPM Engine Overview
  6. 3Multi-Port Power Allocation Policy
    1. 3.1 Assured Capacity Policy
    2. 3.2 Shared Capacity Policy
      1. 3.2.1 Fair Share Power Policy
        1. 3.2.1.1 Blind Sink Support
    3. 3.3 Hybrid Mode
  7. 4Power Foldback Policy
    1. 4.1 Thermal Foldback Operation
    2. 4.2 Engine Start or Stop Transition Management
      1. 4.2.1 Engine Start or Stop Power Foldback Operation Example
  8. 5Multi-Port Power Allocation Policy Examples
    1. 5.1 Assured Capacity Policy Example
    2. 5.2 Fair Share Power Policy Example
      1. 5.2.1 FSP Policy Example – Blind Sink Support
      2. 5.2.2 FSP Policy Example – Blind Sink Support with Max Power
    3. 5.3 Hybrid Mode Example
  9. 6References
  10. 7Revision History

3.1 Assured Capacity Policy

The Assured Capacity Policy is where the sum of the Port Max Power, as designed, is equal to the Total USB VBUS Power.

Equation 1. Total USB VBUS Power = Port A Max Power + Port B Max Power

When the Source ports are configured as Assured Capacity, Port Max Power is guaranteed and each port is able to deliver up to its Port Max Power independent of the second port's status. An example of the Assured Capacity Policy is shown in Figure 3-3 where the Total USB VBUS Power is 60W, Port A's Max Power is 40W, and Port B's Max Power is 20W.

GUID-20231004-SS0I-TQ20-FLMF-CMFSXHC4WPVJ-low.png Figure 3-3 Assured Capacity Policy

The TPS25772-Q1 dual-port PD controller supports two Assured Capacity power modes configurable using the TPS257xx-Q1-GUI. The options are:

  • Max Init (Initialization) Power: Upon connection, the Source will initially send Source Capabilities advertising the maximum power as configured in the GUI.
  • Min Init (Initialization) Power: Upon connection, the Source will initially send Source Capabilities advertising the minimum power as configured in the GUI. Depending upon the responding Sink Capability, the TPS257xx will resend Source Capabilities accordingly.

The recommendation is to always configure for Max Init Power (default GUI setting) unless a different operational mode is preferred based on system requirements. Figure 3-4 and Figure 3-5 show the Assured Capacity Policy selection in the GUI's Simple Configuration view and Advanced Configuration view.

GUID-20230921-SS0I-V80D-TN5F-HFLL1WDQRCQ8-low.png Figure 3-4 Assured Policy GUI Selection – Simple Configuration
GUID-20230921-SS0I-FN8W-LZLK-QTJ380LVX6RG-low.png Figure 3-5 Assured Policy GUI Selection – Advanced Configuration

See Section 5.1 for example scenarios of the Assured Capacity Policy to better understand how system power is allocated and distributed when this SPM Power Policy is selected.