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

3.3 Hybrid Mode

Hybrid Mode is an optional power policy that behaves as a hybrid of the Assured Capacity Policy and Shared Capacity Policy. It provides the benefit of the Assured Capacity Policy by initially advertising the Port Max Power when one Sink is connected, while allowing equal distribution of the Total USB VBUS Power, similar to the Shared Capacity Policy, when two Sinks are connected.

There are some Sink devices that request power based on the first Source Capabilities received and do not attempt to renegotiate for a more favorable contract when higher PDOs are offered in following Source Capabilities messages. This is a problem when FSP is desired, so Source ports are configured as Shared Capacity and Port Min Power is advertised in the initial Source Capabilities message. With Hybrid Mode, FSP is possible while ensuring that the aforementioned Sink-type's power requirements are met.

Hybrid Mode can be enabled from either the Simple Configuration or Advanced Configuration view. After the SPM Engine parameters are entered with Assured Capacity Policy selected, Hybrid Mode can be enabled by modifying the Total USB VBUS Power (System Max Power) to a value less than the sum of Port A and Port B's Max Power. The GUI then displays Hybrid Mode in red text to indicate that Hybrid Mode is active as shown in Figure 3-9 and Figure 3-10.

GUID-20230921-SS0I-JDFC-XT3D-MMFWJRB4R7KL-low.png Figure 3-9 Hybrid Mode GUI Selection – Simple Configuration
GUID-20230921-SS0I-SZ09-FNRN-SPKPJH4RFM84-low.png Figure 3-10 Hybrid Mode GUI Selection - Advanced Configuration

The Hybrid Mode parameters shown in Table 3-5 are used in the power distribution method.

Table 3-5 Hybrid Mode Parameters
Hybrid Mode Parameters Description
Equally Divided System Power Equally divided Total USB VBUS Power distributed to each port when two PD-Sinks are connected:

Total USB VBUS Power / Total number of ports.
Single Port Max Power Capacity Maximum VBUS power for a port when a single PD-Sink is connected:

Total USB VBUS Power - Port Min Power (limited up to the Port Max Power)

Non-PD USB-C Power USB Type-C 5 V output for non-PD based USB Type-C charging; 7.5W or 15W.

The typical flow of the Hybrid Mode power distribution is as follows:

  1. The first connected Source port initially advertises Port Max Power and sends a Get Sink Capabilities request
  2. The Sink responds by returning the Sink Capabilities and receives power accordingly (up to the Single Port Max Power Capacity).
  3. The second Source port connects to another Sink and the SPM Engine immediately distributes the Equally Divided System Power to each Port Partner.

In the event where one PD Sink and one non-PD Sink are connected to the ports, the Equally Divided System Power is initially distributed to each Sink. This connection takes roughly 8.5 seconds for the TPS257xx-Q1 firmware to identify a non-PD Sink. Once a non-PD Sink is identified, the SPM Engine can reallocate and redistribute system power; Non-PD USB-C Power is distributed to the non-PD Sink and the remaining power (the difference between the Total USB VBUS Power and the Non-PD USB-C Power) is distributed to the PD Sink. The Non-PD USB-C Power can be selected by configuring the USB Type-C Current parameter from the GUI's USB PORT(S) window (see Figure 3-11).

GUID-20231010-SS0I-PW4M-V2QG-J7BLWBLP0NR3-low.png Figure 3-11 USB Type-C Current – Advanced Configuration

See Section 5.3 for example scenarios of Hybrid Mode to better understand this mode's power distribution method.