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TPS65987D: Charging device when cable is not detected

Part Number: TPS65987D
Other Parts Discussed in Thread: TPS65987

Hi,

We're using this PD controller in order to manage a USB Type C port connected to a tablet. Our system can either source or sink power from the USB port, and is always an UFP for data. We are switching between sourcing and sinking power depending on whether external AC power is available, using an application microcontroller sending swap-to-source and swap-to-sink commands over the I2C bus.

This works fine when the tablet is on, but when it's turned off (e.g. when its battery is discharged) we can't figure out how to configure the PD controller as a Source and start charging it. It looks like the TPS65987 is not detecting that the cable is plugged in when the tablet is turned off. The tablet supports USB PD, but we suspect that it's not applying the appropriate pulldown on the CC to enable cable detection when it's turned off. The tablet wakes up when plugged into the charger supplied with it, and also when plugged into a laptop USB port with an A->C cable, both of which (I think) are just unconditionally applying 5V on VBUS.

Is there a way to manually turn on the PP2 switch to supply 5V to the device in this case?

Thanks,

Saajan