SLVAF24 April   2021 TPS65988

 

  1.   Trademarks
  2. 1Automatic RDO for Explicit Contracts in SINK Role
    1. 1.1 Autonegotiate Sink Register (0x37)
    2. 1.2 Automatic PDO Selection as a Sink
    3. 1.3 Autonegotiate PDO Selection Flow
    4. 1.4 Autonegotiate Behavior Examples
  3. 2Multi Port Source Policy Management
    1. 2.1 Multi Port Source Policy Management Flow
  4. 3Multiport Sink Policy Management
  5. 4Revision History

3 Multiport Sink Policy Management

The Multiport Sink Policy Management feature of the TPS65988 (dual port) PD controller enables the system to optimize the power drawn when both ports are acting in the Sink power role. The main objective of this feature is to sink power from a port that has higher power contract and disable the sink power path on adjacent port. The power contract on any of the ports is not disturbed. This feature results in only one port actually sinking power. This feature is dependent on the setting of the below bits:

  • MultiPortSinkPolicy [Bits 1:0 of Global System Configuration Register (0x27)]
  • MultiPortSinkNonOverlapTime [Bits 10:9 of Global System Configuration Register (0x27)]

In addition to these bits, setting the bit AutoNgt = 1 [Bit 0 of Auto Negotiate Sink Register (0x37)] will allow for drawing higher power which otherwise would default to 5-V contracts only (First PDO from the list of Source PDOs).

Multiport Sink Policy Management Behavior:

The Multiport Sink Management feature functions with the below criteria:

  • When the port is entering a Sink role in an Implicit / Eplicit or Legacy mode.
  • When in dead battery, the Sink switch would always be enabled.
  • If the adjacent port does not have its Sink switch closed on account of being in a disconnected / Source / Sink (open switch) state, the current port's Sink switch would be enabled.
  • If the adjacent port is already in a Sink contract with its Sink switch closed, the PD contract power of both ports would be compared and the port with the Higher PD contract power would close its switch while the other would be opened (if already closed) or suppressed from closing.
  • In a case where the adjacent port is in a Sink contract and its Sink switch requires to be opened and the current port's Sink switch needs to be closed, the operation would be a break-before-make operation where the below sequence is followed:
    • Open adjacent Sink switch.
    • Wait for a time determined by the setting MultiPortSinkNonOverlapTime (Bits #10:9 of byte 14 of the Global System Configuration Register (0x27)).
    • Close the current port Sink switch.
GUID-CA0204C5-7C56-4B6F-A36A-AE118A9E762B-low.jpg Figure 3-1 Multiport Sink Policy Management Flowchart