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Is the TUSB2046B USB 2.0 Compliant?

Tom Smith
Expert 2930 points
Other Parts Discussed in Thread: TUSB2046B, SN75240

Looking at the datasheet for the TUSB2046B it states "Fully Compliant With the USB Specification as a Full-Speed Hub: TID #30220231". Does this mean it is USB 2.0 compliant?

The reference schematic uses SN75240 (USB port transient suppressors) that have in the datasheet "Note that the input capacitance of the device makes it unsuitable for high-speed USB 2.0 applications". Since the TUSB2540 is a full speed device, using the SN75240 in the design, is it USB 2.0 compliant??

-Tom- 

  • 0
    TI__Genius 16430 points

    Tom,

    The USB 2.0 specification defines three speed nodes:

    • USB Low–speed = 1.5 Mbps
    • USB Full–speed = 12 Mbps
    • USB High–speed = 480 Mbps

    As the TUSB2046B states it is compliant as a full–speed device.  It will enumerate high–speed devices, but limit the throughput to full–speed bit rates. 

    The USB 2.0 specification compliance for full–speed hubs is limited to embedded applications - such as what you find in many keyboards.  As a stand–alone hub box, it is not technically compliant as these type of boxes have to support high–speed.  The typical usage for full–speed hubs are in embedded user interface boxes that embed keyboards, touch screens, track balls, etc.

  • 0 in reply to DHarmon
    Expert 2930 points

    Dan,

    So the TUSB2046B IS USB 2.0 compliant but only at full-speed?

    Tom.

  • 0 in reply to Tom Smith
    TI__Genius 16430 points

    Correct - the USB-IF TID assigned to it is 30220231.