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DS90UB926Q-Q1: Schematic design suggestions

Verna Hong
Prodigy 220 points
Part Number: DS90UB926Q-Q1

Hi

Please help to suggest the schematic design. Thanks.

DS90UB926-SCH.pdf

  • 0
    TI__Expert 6545 points

    Hi Verna,

    Thanks for reaching out. I will take a look at the schematic and provide feedback by the end of next week (9/9).

    Sincerely,

    Ryan

  • 0 in reply to Ryan Fleetham
    TI__Expert 6545 points

    Hi Verna,

    Please see below for my comments:

    • VDD33A/VDD33B - recommendation is to have a single ferrite bead for both pins and one 4.7uF cap per pin.
      • Also ensure that the ferrite bead used is 1kOhm @ 100MHz and less than 1 Ohm of DC resistance.
    • VDDIO - recommendation is to have a single ferrite bead for all three pins and one 4.7uF cap per pin.
      • Also ensure that the ferrite bead used is 1kOhm @ 100MHz and less than 1 Ohm of DC resistance.
    • RIN capacitors C107 and C108 - recommend using 0402 caps instead of 0603
    • CMLOUT - is there a reason for adding C105 and C106 after the 100 Ohm resistor? 
    • Ensure SDA and SCL have appropriate pullup resistors.

    Sincerely,

    Ryan

  • 0 in reply to Ryan Fleetham
    Prodigy 220 points

    Hi  Ryan,

    Thanks for your reply，CMLOUT -  adding C105 and C106 after the 100 Ohm resistor is referenced the design of TI《SAT0059, Automotive Touchscreen》。

    10-3.解串器-DS90UB926Q硬件参考设计原理图-TI.pdf

  • 0 in reply to Verna Hong
    TI__Expert 6545 points

    Hi Verna,

    Thank you for letting me know - I don't see any issues with adding capacitors C105 and C106. Just to clarify my prior comments for the power rails, it is fine to have additional capacitors and ferrite beads like you have and some of our EVMs and designs do have them. The recommendation given is the minimum described by the datasheet.

    Please let me know if you have any questions.

    Sincerely,

    Ryan