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TUSB8020B: Exact meaning of "HUB in U1" and "HUB in U0" | Input supply current

Viral Vasa
Prodigy 100 points
Part Number: TUSB8020B

Hi Team,

We are using part#TUSB9020B. We have supply of 3.3V & 1.1V. Now as per the section 7.7 as below the two terminology is used as hub in U0 & hub in U1. I am not sure what exactly the difference between two. in U0 & U1 ?

The current consumption in U0 on 1.1V rail is 1.5x as compared to U1.

What is required if need to drive the HUB in U1 ?

  • 0
    TI__Guru**** 176581 points

    Hi,

    Please refer to the USB3.2 spec. There are four operational link states, U0, U1, U2, and U3. U0 is a state where an Enhanced SuperSpeed link is enabled or normal mode. Packet transfers are in progress or the link is idle. U1 is low power link state where no packet transfer is carried out and the Enhanced SuperSpeed link connectivity can be disabled to allow opportunities for saving the link power. U2 is also a low power link state. Compared with U1, U2 allows for further power saving opportunities with a penalty of
    increased exit latency. U3 is a link suspend state where aggressive power saving opportunities are possible.

    A port shall attempt to transition to the U1 state in any of the following situations:

    • U1 entry is requested by the link partner and there is no pending traffic on the port
      and all the hub downstream port’s links are in U1 or a lower state.
    • All the hub downstream ports are in U1 or a lower link state and there is no pending
      traffic to transmit on the upstream port and U1_ENABLE is set to one.
    • U1 entry is requested by the link partner and Force_LinkPM_Accept bit is set.

    Thanks

    David