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Original question:

TUSB1044: Backward Compatability

TUSB1004: unused pins

Arun Gomathi R
Prodigy 50 points
Part Number: TUSB1004
Other Parts Discussed in Thread: TUSB522P, TUSB1002A

Tool/software:

Dear Team,

Good day to all!!!

We are using TUSB1004 in our design to compensate the ISI losses of USB3.0 Gen 1 interface.

What is to be done when leaving CTXx, CRXx, SSTXx, SSRXx pins unconnected ?

Whether any termination to be provided for the unused pins ?

Regards,
Arun Gomathi R
Hardware Design Engineer
DATA PATTERNS INDIA LTD
Chennai.

  • 0
    TI__Mastermind 20720 points

    Hi Arun,

    Thanks for reaching out. The TUSB1004 is intended to be used on two Type-A USB interfaces. All CTX/RX and SSTX/RX pins should connect to your host or the Type-A connector.

    If you leave the TX/RX pins unconnected, the device will not enter active mode because their are no terminations on the device transmitters. 

    Each of these transmitters needs to see 90-ohm differential terminations to put the corresponding 1004 port in active mode.

    Can you describe which pins you want to leave disconnected? If you're only using one type-A port a better option is to use the TUSB1002A for USB Gen2 or the TUSB522P for USB Gen1

    Best,

    Shane

  • 0 in reply to Shane Hauser
    Prodigy 50 points

    Hi Shane,

    Thanks for the immediate response.

    USB Port 1 will be connected to USB Type A connector.

    Please find the below pins that will be unconnected in my design.

    1. SSTX2(P&N)
    2. SSRX2(P&N)
    3. CTX2(P&N)
    4. CRX2(P&N)

    Kindly let me know how to terminate these lines when unused.

    Regards,
    Arun Gomathi R
    Hardware Design Engineer
    DATA PATTERNS INDIA LTD
    Chennai.

  • +1 in reply to Arun Gomathi R
    TI__Mastermind 20720 points

    Hi Arun,

    You can leave those pins disconnected if you do not intend on using port 2. You do not need terminations since the port is not needed in active mode. The 1004 has two independent state machines so each port is handled separately:

    As long as the SSTX/RX1 and CTX/RX1 pins are connected correctly, port 1 will work ok.

    Is there a reason you use the TUSB1004 for this application? The TUSB1002A seems like a better fit as it is designed for one port.

    Best,

    Shane