I have a power conscious design where the HX3PD is only needed when an upstream device is present (small percent of the use case).
What is the lowest power state for the part, and what do I need to do to put the part into that state?
If I power up the supply rails (3.3 and 1.2) following the timing defined in the power sequencing section of AN222944, can I just hold all 3 reset pins low (XRES_PD, XRES_DMC, RESET_HUB)?
Will I have a lower power by holding CHIPEN low?
It may be possible and best to disable the supply rails, but that may require extra buffers to make sure the part isn't connected to other, powered, parts of the design.
Reset state is the lowest power state for the hub where all hard reset is done on all three reset pins.
In that state, the power consumption is around 16mA for 1.2V rail and 1mA for 3.3V rail.
Holding CHIPEN low in this state will ideally not change the current consumed.