米6体育平台手机版

SLVAFG6B December 2022 – November 2024 TPS25762-Q1 , TPS25763-Q1 , TPS25772-Q1

5.2.1 FSP Policy Example – Blind Sink Support

This section provides examples of Fair Share Power Policy's power distribution with Blind Sink Support enabled for both ports and in the event of a port connecting to a Sink that fails to return Sink Capabilities correctly. Note that the Max Power option is not enabled in these examples. Table 5-6 shows the SPM Engine parameters used in this section's example. The FSP Parameters shown in Table 5-7 are used in the Fair Share Power Policy's power distribution to achieve FSP between two Sinks.

Table 5-6 SPM Engine Parameters - FSP Example with a Blind Sink

SPM Engine Parameters	Configuration	Description
System Max Power	75W	Total system power capacity allocated for Port A and B
Port A Max Power	60W	Maximum Port A Power
Port B Max Power	60W	Maximum Port B Power
Port A Min Power	15W	Minimum Port A power
Port B Min Power	15W	Minimum Port B power
Shared Mode	FSP with Blind Sink Support	Port Max Power is offered to Blind Sinks

Table 5-7 Fair Share Power Policy Parameters

Fair Share Power Policy Parameter	Value	Description
Equally Divided Shared Power	(75-(15+15))/2=22.5W	Shared power for each port that can be distributed if available: (Total VBUS power – Sum of Port A and B's Min Power)/Total number of ports
Per Port Guaranteed FSP	15+22.5W=37.5W	Port Min Power + Per Port Equally Divided Shared Power = Per Port Guaranteed FSP

Three example scenarios of Fair Share Power Policy operation (when Blind Sink Support is enabled) are shown in Table 5-8. The table format in this section is structured differently to show how Blind Sinks are handled and supported by the SPM.

Table 5-8 FSP Example With Blind Sink Support

	Port A	Port B	SPM Operation Description
Initially Allocated	15W	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	15W		The first Source Cap is sent to Port A's Sink with Port Min Power.
Sink Request	15W		Grant 15W to Port A.
Sink Cap	45W		Source sends Get Sink Cap message to Port A and max 45W Sink Cap is returned.
Source Cap 2	45W		A 45W Source Cap is sent again based on Sink Cap.
Sink Request	45W		Port A Sink requests 45W.
Power Distributed to Sink	45W		45W distributed to Port A Sink.
Scenario 2: Port A is replaced with a Blind Sink. Port B is still unconnected.
Source Cap 1	15W		The first Source Cap is sent to Port A's Sink with Port Min Power.
Sink Request	15W		Grant 15W to Port A.
Sink Cap	15W		Source sends Get Sink Cap message to Port A. Source Cap = Sink Cap is returned. Port A Sink is identified as a Blind Sink.
Source Cap 2	60W		A Source Cap is sent again with Port Max Power.
Sink Request	60W		Port A Sink requests 60W.
Power Distributed to Sink	60W		60W 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		15W	The first Source Cap is sent to Port B's Sink with Port Min Power.
Sink Request		15W	Grant 15W to Port B.
Sink Cap		20W	Source sends Get Sink Cap message to Port B and max 20W Sink Cap is returned.
Source Cap 2	55W	20W	Port A Sink's required power is less than the Per Port Guaranteed FSP. Port B's required power is higher. The SPM distributes power to the Port A's Sink requesting lower power and the remaining power to Port B's Sink.
Sink Request	55W	20W	Port A Sink requests 55W and Port B Sink requests 20W.
Power Distributed to Sinks	55W	20W	55W distributed to Port A Sink. 20W distributed to Port B Sink.

Figure 5-5, Figure 5-6, and Figure 5-7 show the PD negotiation flow of the FSP examples from Scenario 1, Scenario 2, and Scenario 3 of Table 5-8, respectively.

Figure 5-5 FSP Negotiation Flow With Blind Sink Support – Scenario 1

Figure 5-6 FSP Negotiation Flow With Blind Sink Support – Scenario 2

Figure 5-7 FSP Negotiation Flow With Blind Sink Support – Scenario 3