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TPS65981: Can't charge a device that isn't powered

Part Number: TPS65981

Our device uses the TPS65981 as a PD controller. It is a UFP, but it is capable of doing a power role swap in order to charge the connected host device. This is all working fine when the connected device is powered on. The BARREL_JACK_DET gpio is triggered and the role swap succeeds. However, if the connected device is turned off, triggering the BARREL_JACK_DET input has no effect. When a charger is connected to a device that is off, I believe it begins by providing standard 5V to the device, and can then negotiate to other power levels. Is there a way to get the TPS65981 to provide this initial power to a device that is off in order to function as a charger?

  • As a follow-up to my own question, could the problem be that my system configuration Port Information field is set to "Presents R_d on CC, supports data/power role swap"? Should it be "Toggles R_p/R_d on CC..."? I don't want to be the data source, so should I use the "no try.Src" option? I have both "Process Swap to UFP" and "Initiate Swap to UFP" selected in the Control Configuration, but neither process or initiate swap to DFP.

  • Hi Anthony,

    When the TPS65981 does not have VIN_3V3 available, it can only become a Power Sink. If you need TPS65981 to become a power source, VIN_3V3 must be provided. The TPS65981 cannot become a power source without VIN_3V3 available. 

    If the TPS65981 has VIN_3V3 available and is configured to present Rp either by toggling the CC line or only presenting Rp, the TPS65981 can provide power to another device that is off. As long as that other device presents Rd on the CC line. 

    Thank you,
    Eric