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TUSB7320

Sachin Kurawatti
Prodigy 130 points
Other Parts Discussed in Thread: TUSB7320

Hi,

I would like to understand below mentioned scenario.

TUSB7320 support two downstream. I will connect two USB 3.0 devices to the downstream. Will the PCIe root complex be able to access both the devices at 5Gts transfer mode?

Please Suggest.

Regards,

Sachin.M.Kurawatti 

  • 0
    TI__Guru* 76130 points

    Hello,

    PCIe Gen I only supports 2.5Gbps.

    PCIe Gen II supports 5Gbps.

    Of course, you are never going to "see" 5Gbps of "active data" going from one device to another, there are a lot codification that reduces the throughput.

    But, the raw answer is Yes, the TUSB7320 will transfer data to both downstream devices at Super Speed rates with no problem.

    Regards.

  • 0 in reply to Elias Villegas M.
    TI__Genius 16430 points

    One thing to add is that the way the USB bus is actually architected is that the host only is transmiiting to any one given device at any instant in time, so the throughputs match at 5 Gbps and 8b/10b encoding.

    However, the host will time share between two attached devices and so if you had two peripherals that were actaully capable of providing close to 4 Gbps of real data throughput (after the 8b/10b encoding is stripped down), then they would be time sliced by the host. 

    The actual theoretical "data" max that a USB 3.0 device can achieve in real throughput is around 3.68 Gbps after the protocol overhead is added to the data bits to get to the 4 Gbps data bit rate which is then encoded to 5Gbps.  However even most raid drives today have trouble getting to this number.