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

5.2.2 FSP Policy Example – Blind Sink Support with Max Power

This section provides three additional examples of Fair Share Power Policy's power distribution, but with Blind Sink Support and Max Power enabled for both ports, and are shown in Table 5-9. With these two FSP settings enabled, Port Max Power is always advertised after the initial Source Capabilities message regardless of the Sink's behavior. The SPM Engine Parameters for these examples are the same as shown in Table 5-6

Table 5-9 FSP Example with Blind Sink Support and Max Power
Port A Port B SPM Operation Description
Initially Allocated 15 W 15 W Min Power is initially allocated for Port A and Port B.
Scenario 1: Port A connects to Good Sink 1. Port B is unconnected.
Source Cap 1 15 W The first Source Cap is sent to Port A's Sink with Port Min Power.
Sink Request 15 W Grant 15 W to Port A.
Sink Cap 45 W Source sends Get Sink Cap message to Port A and max 45 W Sink Cap is returned.
Source Cap 2 60 W Source Cap is sent again with Port Max Power since Max Power is enabled.
Sink Request 60 W Port A Sink requests 60 W.
Power Distributed to Sink 60 W 60 W delivered to Port A Sink.
Scenario 2: Port A is replaced with a Blind Sink. Port B is still unconnected.
Source Cap 1 15 W The first Source Cap is sent to Port A's Sink with Port Min Power.
Sink Request 15 W Grant 15 W to Port A.
Sink Cap 15 W Source sends Get Sink Cap message to Port A. Source Cap = Sink Cap is returned, but is a don't care with Max Power enabled.
Source Cap 2 60 W A Source Cap is sent again with Port Max Power.
Sink Request 60 W Port A Sink requests 60 W.
Power Distributed to Sink 60 W 60 W is distributed to Port A Sink.
Scenario 3: Port B connects to Good Sink 2. Port A continues to deliver 60 W to Blind Sink.
Source Cap 1 15 W The first Source Cap is sent to Port B's Sink with Port Min Power.
Sink Request 15 W Grant 15 W to Port B.
Sink Cap 20 W Source sends Get Sink Cap message to Port B and max 20 W Sink Cap is returned.
Source Cap 2 37.5 W 37.5 W Max Power is enabled, so Per Port Guaranteed FSP is advertised to both Sinks regardless of Sink Capabilities.
Sink Request 37.5 W 37.5 W Port A and B's Sinks request 37.5 W.
Power Distributed to Sinks 37.5 W 37.5 W(1) Each Sink gets Per Port Guaranteed FSP of 37.5 W.
(1) Some Sink devices return a Sink Capabilities message that is lower than what they are actually able to consume. The Max Power option can be adopted to support higher power charging for Sink devices such as these.

Figure 5-8, Figure 5-9, and Figure 5-10 show the PD negotiation flow of the FSP examples from Scenario 1, Scenario 2, and Scenario 3 of Table 5-9, respectively.

GUID-20231027-SS0I-GLC1-QQTC-7JQD5NS7RQVZ-low.png Figure 5-8 FSP Negotiation with Blind Sink Support & Max Power - Scenario 1
GUID-20231027-SS0I-9F6T-2M7X-KLRWLXKGLTNX-low.png Figure 5-9 FSP Negotiation with Blind Sink Support & Max Power - Scenario 2
GUID-20231031-SS0I-NFFP-VCC4-SD4BJR3ZBRG6-low.png Figure 5-10 FSP Negotiation with Blind Sink Support & Max Power - Scenario 3