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TUSB8041: what if I not use USB 3.0 AC Coupling Capacitor

Seokmin Hong
Intellectual 485 points
Part Number: TUSB8041

I am using TUSB8041 for USB Hub.

But when I connect to usb 3.0 devices for downstream, CPU and TUSB8041 cannot recognize USB3.0 devices but can only recognize USB2.0 devices.

Only works with High speed. (CPU(upstream)-TUSB8041-USB Devices(downsream))

While debugging I found in the schematic, that I didn't put ac coupling capacitors in TX/RX lines. Are these must be in the lines? 

Will this effect(excluding ac cap) that CPU can not recognize USB 3.0 and work with only high speed not super speed.?

In other words, Usb high speed and super speed are decided by whether those ac coupling capacitors?

If not, could anyone recommend what else I can do to recognize usb 3.0?

Thanks.

  • 0
    TI__Guru 60870 points

    Hello Seokmin,

    Yes, the AC coupling caps are required for the SSTX/SSRX (USB 3.0) to work properly.  Without them all signalling will occur over the DP/DM lines (USB 2.0).  These will need to be reworked into your design for the USB 3.0 to function.

    Regards,

    JMMN