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TM4C1231D5PM: Possible problem with LQFP64 adapter.

Pawel Kowalsky
Prodigy 130 points
Part Number: TM4C1231D5PM

Hello,

I want use adapter with LQFP64  to THT in my PCB. For example:

And I have question. If I use this adapter, crystal oscillator will be on bottom layer (microcontroller will be in top layer on the adapter).

So wire between microcontroller and oscillator will be long. In this wire flows high frequency. It doesn't break microcontroller work? 

Whether it doesn't matter ?

Thanks for answer.

regards,

Pawel

  • 0
    TI__Guru**** 158915 points

    Hi,

      You must keep the crystal as close as possible to the OSC0/OSC1 pins. Please refer to the 3.7.2 section in the system design guideline app note. http://www.ti.com/lit/an/spma059/spma059.pdf

  • 0
    Guru 117850 points

    My friend,

    Pawel Kowalsky said:
    wire between microcontroller and oscillator will be long.

    How do you define, 'long?'    

    My firm has done (very) similarly (w/success) - yet employed these guidelines:

    • choose the lowest xtal frequency which is acceptable to your MCU.   (lower frequency better accommodates such kludge)    (you will likely be stuck if you employ USB)
    • mount the xtal osc. to a small board - then attach it as 'near as possible' to the MCU (and on the same side as the MCU.)

    Note that this procedure is for 'Desperation Only' consideration.   It proves a 'Quick & Dirty Means' to gain (some) operation and/or MCU insight - yet should not be considered for, 'Release to the Field.'