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

5.1 Assured Capacity Policy Example

This section provides examples of power distribution when Source ports are configured as Assured Capacity Policy and Max Init Power mode is selected. Table 5-10 shows the SPM Engine parameters used in this section's example.
Table 5-1 SPM Engine Parameters - Assured Capacity Policy Example
SPM Engine Parameters Configuration Description
Total USB VBUS Power (System Max Power) 105 W(1) Total system power capacity allocated for Port A and B
Port A Max Power 60 W Maximum Port A Power
Port B Max Power 45 W Maximum Port B Power
Port A Min Power 15 W Minimum Port A power
Port B Min Power 15 W Minimum Port B power
Assured Mode Max Init Power Source initially sends Source Capabilities advertising max power
(1) The Total USB VBUS Power is 105 W; the sum of Port A Max Power and Port B Max Power.

Three example scenarios of Assured Capacity Policy are listed in Table 5-2. Note that the power distributed to each port is independent of the other port's status as is expected with the Assured Capacity Policy.

Table 5-2 Assured Capacity Policy Example
Port A Port B
Initially Allocated 60 W 45 W
Scenario 1: Port A connects to a Sink that requires 27 W. Port B is unconnected.
Power Required by Sink 27 W
Power Distributed to Sink 27 W
Scenario 2: Port B connects to a Sink that requires 45 W.
Power Required by Sink 27 W 45 W
Power Distributed to Sinks 27 W 45 W
Scenario 3: Port A changes the requirement to 60 W.
Power Required by Sink 60 W 45 W
Power Distributed to Sinks 60 W 45 W

The following diagrams show the flow of the PD negotiation when Assured Capacity Policy is enabled and where one Sink first connects to Port A (Figure 5-1) and a second Sink connects to Port B (Figure 5-2).

GUID-20231017-SS0I-GZDH-Z7C0-GDQ94J8DN2CR-low.png Figure 5-1 Assured Capacity Policy Negotiation Flow - Port A Connected
GUID-20231017-SS0I-3KMJ-0VH9-CG6ZPMWPLV4N-low.png Figure 5-2 Assured Capacity Policy Negotiation Flow - Port B Connected