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TUSB2036 Device Not Recognized

Leo Stevens
Prodigy 10 points
Other Parts Discussed in Thread: TUSB2036

I'm getting the "Device Not Recognized" message while trying to connect my PC (Windows 7 Professional).  I've checked other threads in the TI forums but I don't see anyone trying to use the TUSB2036 in a self-powered design.  I'm attaching a PDF of my schematic.  I'm only using two ports.  The first port goes directly to an Atmel micro-controller USB port.  The second port goes to an FTDI USB to UART chip.  Both are always connected.  I'm not using external memory and I'm using a 48 MHz clock oscillator connected directly to the TUSB2036 (extremely close...very short trace from clock output to the TUSB2036).  I'v tried connecting after power-up, connecting before power-up, and even forcing a reset after power-up and connection.  I always get the same error message.  Any help would be most appreciated.

LeoUSB_Hub-1.pdf

  • 0
    TI__Mastermind 18655 points

    Hello Leo, 

    According to your schematics, the upstream and downstream ports have a series resistor of 24.9K Ohms. Per USB 2.0 specification, the differential impedance must be 90-Ω differential or 45-Ω single-ended. Having series resistors between 22 Ω to 33 Ω along with internal resistance of the device ensures that the impedance matches this specification. 

    Regards.