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Original question:

TPS25750: PD re-negotiation

TPS25750: pd negotiation not triggered after loading low region binary

Ck Lam
Prodigy 60 points
Part Number: TPS25750

Using the TPS25750 EVM and removing the J14 jumper to bypass loading of eeprom data, I managed to transferred the low region binary using the 4CC commands and PD is in the APP mode. However, there is no PD negotiation triggered, the voltage is remained in 5V. ( was expecting to become 9V). 

Upon reading some of the register settings, the dead battery flag is set, and the status.ActingAsLegacy is 3, there is no active contract pdo.

I tried to use to DBfg to clear the dead battery flag, but it seems this command resulted in the PD got reset and back to the PATCH mode? Do you have any idea why?

How to kick start the PD negotiation after loading the low region data?

  • 0
    TI__Genius 15275 points

    Hi CK,

    Are you using TPS25750EVM as a source and using the GUI to generate your configuration?

    Regards,

    Brandon

  • 0 in reply to Brandon Beader
    Prodigy 60 points

    Hi Brandon,

    I am using the EVM as sink and the low region binary is generated from the GUI.

    Since I flash the binary by MCU over I2C and disconnected the Jumper J4 on EVM, can you confirm that the S1 switch should be set to "SafeMode" or set to some other configuration?

    Also, are you able to tell under what circumstances the mode register gives "BOOT" or "PTCH" value?

    Additional questions:

    If i set to EVM to "Always Enable Sink", i noticed what even there is no eeprom, the mode register is giving me "APP". The TRM mentioned "USB PD is disabled until configuration is loaded." in this mode:

    1. Is the configuration here refer to the low region binary?
    2. If using "Always Enable Sink", what is the command to go into "PTCH" mode? I tried to GO2P & GAID, both command giving me !CMD.

    Thanks.

  • +1 in reply to Ck Lam
    TI__Genius 15275 points

    Hi CK,

    Since you are loading your configuration from MCU, you would want to be in AlwaysEnableSink mode which is the preferred method of loading a configuration from MCU. This will allow the sink path to be enabled so that system can provide power to MCU for flashing.

    AlwaysEnableSink should not boot into APP mode unless there is a valid configuration loaded. If you have an EEPROM attached, it will load configuration from the EEPROM and boot into APP mode. Make sure there is no EEPROM attached. 

    Regards,

    Brandon