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TPS65982 EVM: change the setting online

Botao Miao
Prodigy 70 points
Other Parts Discussed in Thread: TPS65982

Here is another question. If I want to use the EVM board as a sink device, I can set it as configuration ID 7.  In this mode, it has two capabilities: 

1) Voltage 12-20 @ 3A

2) Voltage 20 @ 5A

During the PD connection, how can I trigger a transient, such as voltage change, current change or power change?  I want to use this device to fully test my USB charger system.

  • 0
    Prodigy 70 points
    if I want to change the voltage level from 20V to 5V online, what should I do?
  • 0
    TI__Expert 5330 points
    Hello Botao,

    The power autonegotiation capability of the TPS65982 is static (with a few exceptions, such as the "Barrel Jack Detect") meaning that, when the connection is first made between power source and sink, the source will provide its power sourcing capabilities, the sink will request one of the capabilities from the list, and this will be the power contract.

    It is possible to transition between power levels as you describe, but it requires an external controller interacting with the TPS65982 over the host interface. The EC can do one of two things:
    1. Reprogram the sink capabilities of the device so that the original contract is no longer available, forcing a change on the next autonegotiation.
    2. For more complex interactions, the EC can use "intrusive mode" which disables the autonegotiation but requires EC to drive the sink request protocol.

    In either case, the sink will trigger a re-negotiation of a new contract by sending a "GSrC" (get source capabilities) request using the "GSrC" 4cc command. If autonegotiation is enabled, the TPS65982 will complete the new negotiation using its new settings. If intrusive mode is enabled, the EC will have to drive the process to completion.
  • 0 in reply to Steve Preissig
    Prodigy 70 points
    Hi Steve,

    Thanks for the answer. What's the EC?

    In the method 1), what will happen during the transient during the next autonegotiation?

    Thanks,

    -BM
  • 0 in reply to Botao Miao
    Prodigy 50 points

    Hi Steven,

    If it use the intrusive mode, does it need to use GSrC to re-negotiation of a new contract? GSrC will make a On/Off transient on the PP_HV side. If it does not want the transient, can using intrusive mode avoid it?

    Best Regards

    Philip Jou