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TUSB4020BI: Crystal Output limiting resistor

Hiroshi KOMORI
Prodigy 10 points
Part Number: TUSB4020BI

Hi team.

A product using TUSB4020BI has a rare problem that communication stops during USB data transmission.

Our circuit inserts a limiting resistor of 1.8kΩ. I checked the TUSB4020BI datasheet and Schematic Checklist, but I didn't insert a limiting resistor.

Is it possible that the limiting resistor is adversely affecting the operation of the TUSB4020BI?

Is there a document for the equivalent circuit inside the XI and XO pins of the TUSB4020BI?

Best regards,
KOMORI

  • +1
    TI__Guru**** 152516 points

    Komori-san

    The limiting resistor controls the amount of feedback and crystal oscillator drive. 

    So if you have too high resistance the oscillator will not start reliably under all conditions.

    If you have too low resistance you may exceed the maximum power dissipation specification of the crystal, causing premature aging, drift and even failure.

    Please refer to the crystal oscillator datasheet and make sure the crystal oscillator drive power is in a sensible range.

    Thanks

    David

  • +1 in reply to David (ASIC) Liu
    Prodigy 10 points

    David-san

    Thank you for answering.

    Check the specs of the crystal oscillator.