• State TI Thinks Resolved
  • Locked Locked
  • Replies 1 reply
  • Answers 1 answer
  • Subscribers 34 subscribers
  • Views 227 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.

TUSB8041-Q1: Design problems

Che Wen Yeh
Expert 1330 points

Part Number: TUSB8041-Q1
Other Parts Discussed in Thread: TUSB8041

Tool/software:

Hi Teams,

We have encountered some design issues with the TUSB8041IPAPRQ1 as listed below. Could you please review and confirm? Thanks.

1. The datasheet specifies the crystal's ESR must be less than 50Ω. How significantly does ESR affect performance?

We have currently selected a crystal with 80Ω ESR – could you please evaluate whether this is acceptable for use?

2. For PIN18 (GRSTz), the datasheet describes it as a global power reset. The reference design connects it to ground via a capacitor.

How does this configuration achieve reset functionality? Should a resistor and power connection be added as shown in the diagram below?

  • 0
    TI__Guru**** 158955 points

    Hi Che:

      For GRSTz, there is internal pullup resistor on this pin. With external Cap, the RC circuit will keep low for sometime after VDD33/VDD is stable. GRSTz low will reset the hub. 

      For crystal ESR , it's proportional to the loop gain needed for the oscillator to start up and sustain oscillation. The higher ESR, it's more difficult to start up.

    TUSB8041 oscillation circuit was designed based on 50 ohm ESR crystal, but if  crystal with 80 ohm ESR  still can oscillate , I didn't see any other issue.

    Best

    Brian