• State TI Thinks Resolved
  • Locked Locked
  • Replies 6 replies
  • Answers 1 answer
  • Subscribers 33 subscribers
  • Views 3388 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TUSB501: IBIS model and hyperlynx simulation

Nicola Fiorucci
Intellectual 300 points
Part Number: TUSB501

Hi,

i'm simulating an USB3.0 bus. The path is composed by an smd connector, the TUSB501, ESD diode and finally an USB3.0 type A connector.

I downloaded the IBIS model for the TUSB501 from TI website.

I use the IBIS model also for the connectors to emulate a transmitter and receiver. So i assigned the TUSB tx output pair to the smd connector and the TUSB rx input pair to the type A USB conector.

I assigned also the power supply voltage level to the nets.

I  have no idea on how to set the DE, OS and EQ pin for the TUSB501.

At the output of the TUSB501 i have 100nF in series for the TX_p and the TX_n line.

The picture show the model assigned to the TUSB501 redriver (IC3102)

This is the stimulus for the smd connector (SSTX output pair modeled as TUSB501 tx output pair):

This is the IC3102 input signal at pin 2 and 3:

This is the differential signal

and this is the output signal at the output of the TUSB501 pin 6 and 7. I DON'T KNOW WHY

I have no signal at the output.

Please help me

Thanks

  • 0
    TI__Mastermind 36085 points
    Hello Nicola,

    I haven't used the IBIS model but I think you must include the 45 - 50 Ohms loads on the TX pairs, so the re-driver enables its output. THis assumption is based on the fact that the TUSB501 requires this load to enable its channel. I will try to run the IBIS model as well in case the loads don't solve your issue.

    Regards,
    Diego.
  • 0 in reply to Diego Cortes
    Intellectual 300 points

    Hello Diego,

    thanks very much for your help. I will try for insert the load.

    I have some questions.

    I didn't read on the datasheet about the 50ohm loads to enable the TUSB501 output. Is this needed only for simulation purpose or this will affect also the functionality of my PCB circuits?

    According to datasheet the TUSB501 have termination at input and output pair. So i think that also the ibis model will take into account of this termination.

    Thanks again

  • 0 in reply to Nicola Fiorucci
    TI__Mastermind 36085 points
    Hello Nicola,

    There is a detection block which is periodically looking for a USB3 receiver, by detecting its input impedance.

    I agree that the datasheet is not clear about this detail, it is only mentioned in the second paragraph of the description, but you can find a detailed description of the procedure in the USB3.0 specification, section 6.11 - Receiver detection.

    My assumption is based on the simulation result, where the TUSB501 seems to be inactive and the mos probably cause would be the absence of this resistive load.

    NOTE: Please also include the TX AC coupling capacitors between the TUSB501 and the connector. the recommended value is 100nF

    Regards,
    Diego.
  • 0 in reply to Diego Cortes
    Intellectual 300 points

    Hello Diego,

    i tried to put a 100ohm differential termination between pin 6 and 7 of the redriver using hyperlynx termination feature but this didn't resolve the problem. The capacitors are present between tx pair of the redriver and connector.

    what is the best position for the resistor termination? Is it at the redriver output or after the 100nF capacitors?

    Thanks

  • 0 in reply to Nicola Fiorucci
    TI__Mastermind 36085 points
    Nicola,

    Please try using independent 50 Ohm terminations to GND, these terminations must be placed after the AC coupling caps.

    Regards,
    Diego.
  • 0 in reply to Diego Cortes
    Intellectual 300 points

    Hello Diego,

    thanks very much for your help.

    I tried your solution but nothing seems to work. No signal at the output of the TUSB.

    I have another doubt:

    Month ago i posted this thread about the TUSB501: https://e2e.ti.com/support/interface/usb/f/1008/t/613275?tisearch=e2e-sitesearch&keymatch=tusb501

    Now i have board in my hand and only the tx path is working. The mux is an NXP CBTL02043A and it is passive.

    Do i need to place a resistor termination at the output of the lower redirver? (the redriver whose tx signal pair enter in the mux from right side)

    Regards

    Nicola