I'm working with the TPS25750 configured as a PD DRP UFP USB-C Plug with a USB 2.0 hub IC. I've been having several issues with the USB devices behind the hub not re-enumerating after power role swaps and generally inconsistent behavior.
Our design uses an EC to load the App Configuration bundle at boot and we have our ADCINx configured to AlwaysEnableSink. We've been able to successfully load the patch configuration and the TPS25750 seems to work until we remove the external power source and the Dead Battery Flag is set.
After reapplying the external power source and sending the DBFg command I typically see one of two sequences:
1. There is no USB PD communication observed in our USB PD sniffer. The phone we're plugged into repeatedly sends Source Capabilities messages, but the TPS does not respond. After unplugging and reinserting the USB-C plug we see the same sequence. The device reports that it is still in App mode at this point.
2. The TPS will enter Patch mode.
My questions:
1. My understanding was that the TPS will not enter Patch mode except at boot. Does this indicate that the TPS is losing power or crashing during/after the PRS? Our EC does not lose power, so I think it's safe to assume that the TPS has enough power to stay powered.
2. Is there a complete list of 4CC commands? We came across this post TPS25750: Is there a way to reset the tps25750? and it seems like there's some undocumented commands that the TPS supports which are not listed in the datasheet or the Host Interface TRM.
Thanks in advance,
Carson
