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TUSB8044AEVM: Question about 5V Power Supply Current to 4 USB-A 3.2 Ports

Part Number: TUSB8044AEVM
Other Parts Discussed in Thread: TUSB8044A

Tool/software:

Hello,

From the TUSB8044A EVM documentation:

The TUSB8044A EVM operates from the power provided by a 5-V wall power adapter, J6, not bus power supplied by a USB host. TI recommends to use a wall power adapter that is capable of sourcing 2 to 3 A because the hub must be able to source significant power on its downstream ports (900 mA per port).

I'm wondering why the recommendation is sourcing 2-3 A specifically?  If there are 4 USB-A 3.2 ports downstream, would they not need ~3.6A total to be powered fully?

Is the recommendation under the assumption the USB ports are never at max load?  

Thanks in advance for any answers.

  • Hi Joseph:

          max power  consumption for hub  is 680ma for 1.1v and 45ma for 3.3v when 4 SS devices are connected.

         but source  power on its downstream ports (900 mA per port)  is from VBus on each port. not from hub

        5-V wall power adapter need to supply all hub power  consumption and the device attached.

    Best

    Brian