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TUSB8041-Q1: USB Hub Throughput performance of TUSB8041 vs TUSB8042

Steve Clark2
Prodigy 20 points
Part Number: TUSB8041-Q1
Other Parts Discussed in Thread: TUSB8041, TUSB8042

I am seeing decreased performance of the TUSB8041 Hub with one device connected, no other ports used.  About ~250MB/s.  The upstream port in testing get support a sustained transfer of about ~400MB/s.  I can't explain the performance difference.  And a second question is I may want to change the design to use the TUSB8042 device instead, what is the performance difference (in throughput) compared to the TUSB8041?

Thanks

SC

  • 0
    TI__Guru 60865 points

    Hi Steve,

    There is no throughput difference between the TUSB8041 and TUSB8042 devices.

    Are you seeing the throughput difference on USB 2.0 or USB 3.0?  Typically, throughput should increase slightly behind a hub because it allows for some packet buffering.  There may be some impact from power state implementation on USB 3.0.

    Regards,

    JMMN

  • 0 in reply to JMMN
    Prodigy 20 points

    USB 3.0 is what I am using, getting ~200->250MB/s.  What is the expected maximum tested bandwidth of the TUSB8041 hub using USB 3.0?

    SC

  • 0 in reply to Steve Clark2
    TI__Guru 60865 points

    Hi Steve,

    Typical USB 3.0 SSD based mass storage devices max out at around 350 MB/s, we don't see any impact in that throughput from the hub.  It sounds like if you are seeing an impact from the hub, either the device or the host is accepting entries to low power states when it shouldn't and this is decreasing throughput.  If you have an EEPROM or SMBUS host, you can disable U1U2 power states in a register of the hub (bit 5 of Register 05h) to see if that resolves the issue.

    Regards,

    JMMN