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TPS25751: How to break the tie when TPS25751(DRP & Try.SNK) is connected to another PD capable device(DRP & Try.SNK) ?

zong xu
Prodigy 130 points
Part Number: TPS25751

Tool/software:

Hi TI Expert,

The background: the requirement specify that TPS25751 behave as sink when connect to power bank/laptop/tablet etc, but behave as source when connected to some mobile device such as phone, my currrent configuration for TPS25751 is DRP & Try.SNK, it works OK when connected to power bank/laptop, but has problems when connected to phone(continuous PR swap between 2x ports), which is expected.

So my question is that how to break the tie when TPS25751(DRP & Try.SNK device) is connected to another DRP & Try.SNK device(for example: phone), and make sure TPS25751 behave as source when it is connected to phone(DRP & Try.SNK)? Is there a designated register which can achieve this?

BR

  • 0
    TI__Mastermind 37855 points

    Hi Zong,

    PR swaps are initiated by the "preferred power role" question and "Initiate swap to ...." field in the port control register.

    Try.SNK only affects the original connection state.

    The only way to prevent the PRSwap at this point of time would be to disable the "process swap to sink". This will reject a PR_SWAP request from the far-end if the TPS25751 is currently a source.

    Taking a step back:

    Port Config TypeC state machine and Type-C support options configures the initial connection state. On connect, the port type and behavior (Try.sink Try.Source) are defined by these two fields.

    Once a PD contract has been negotiated, the Port Control "Initiate ... " and "Process ... " fields control the behavior. The "Initiate ..." fields will trigger power role swaps asserted by the TPS25751 (if not in the desired power role). The "Process ... " fields control when PR_Swaps from the far end are accepted.

    Never have both "Initiate .." fields set, as you will see an infinite loop of power role swaps coming from the TPS25751.

    Thanks and Regards,

    Chris